diff --git a/.github/bug_report.md b/.github/ISSUE_TEMPLATE/bug_report.md
similarity index 100%
rename from .github/bug_report.md
rename to .github/ISSUE_TEMPLATE/bug_report.md
diff --git a/.github/feature_request.md b/.github/ISSUE_TEMPLATE/feature_request.md
similarity index 100%
rename from .github/feature_request.md
rename to .github/ISSUE_TEMPLATE/feature_request.md
diff --git a/.github/workflows/node.js.yml b/.github/workflows/node.js.yml
index af7b292..4277e37 100644
--- a/.github/workflows/node.js.yml
+++ b/.github/workflows/node.js.yml
@@ -38,7 +38,7 @@ jobs:
 
     steps:
       - name: Checkout
-        uses: actions/checkout@v3
+        uses: actions/checkout@v4
         with:
           # Make sure the actual branch is checked out when running on pull requests
           ref: ${{ github.head_ref }}
diff --git a/CHANGELOG.md b/CHANGELOG.md
index be83f3c..0deaf69 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,3 +1,9 @@
+## 0.15.0-0
+- async/await `send()` support
+- Upgrade dependencies
+- Improvements in filter method
+- Improvements in documentation
+
 ## 0.14.0
 - Upgrade dependencies
 - Support for Node v20
diff --git a/README.md b/README.md
index 8be77b0..4da624a 100644
--- a/README.md
+++ b/README.md
@@ -86,7 +86,55 @@ Note that the Express middleware handler will pick up and transmit any `err` obj
 
 ## Documentation
 
-### Callbacks
+### Send
+
+The `send()` function is asynchronous and returns a `Promise` of type `IncomingMessage`.
+
+Note that `IncomingMessage` can be `null` if the request was stored because the application was offline.
+
+`IncomingMessage` is the response from the Raygun API - there's nothing in the body, it's just a status code response. 
+If everything went ok, you'll get a 202 response code. 
+Otherwise, we throw 401 for incorrect API keys, 403 if you're over your plan limits, or anything in the 500+ range for internal errors.
+
+We use the nodejs http/https library to make the POST to Raygun, you can see more documentation about that callback here: https://nodejs.org/api/http.html#http_http_request_options_callback
+
+You can `await` the call to obtain the result, or use `then/catch`.
+
+#### Using `await`
+
+Use `await` to obtain the `IncomingMessage`, remember to `catch` any possible thrown errors from the `send()` method.
+
+```js
+try {
+  let message = await client.send(error);
+} catch (e) {
+  // error sending message
+}
+```
+
+#### Using `then/catch`
+
+You can also use `then()` to obtain the `IncomingMessage`, as well, use `catch()` to catch any possible thrown errors from the `send()` method.
+
+```js
+client.send(error)
+  .then((message) => {
+    // message sent to Raygun
+  })
+  .catch((error) => {
+      // error sending message
+  });
+```
+
+### Legacy `sendWithCallback`
+
+```javascript
+client.sendWithCallback(new Error(), {}, function (response){ });
+```
+
+The client still provides a legacy `send()` method that supports callbacks instead of `Promises`.
+
+**This method is deprecated and will be removed in the future.**
 
 The callback should be a node-style callback: `function(err, response) { /*...*/ }`.
 *Note*: If the callback only takes one parameter (`function(response){ /*...*/ }`)
@@ -98,7 +146,7 @@ backwards compatibility; the Node-style callback should be preferred.
 You can pass custom data in on the Send() function, as the second parameter. For instance (based off the call in test/raygun_test.js):
 
 ```javascript
-client.send(new Error(), { 'mykey': 'beta' }, function (response){ });
+client.send(new Error(), { 'mykey': 'beta' });
 ```
 
 #### Sending custom data with Expressjs
@@ -113,19 +161,11 @@ raygunClient.expressCustomData = function (err, req) {
 };
 ```
 
-### Callback
-
-```javascript
-client.send(new Error(), {}, function (response){ });
-```
-
-The argument to the 3rd argument callback is the response from the Raygun API - there's nothing in the body, it's just a status code response. If everything went ok, you'll get a 202 response code. Otherwise we throw 401 for incorrect API keys, 403 if you're over your plan limits, or anything in the 500+ range for internal errors. We use the nodejs http/https library to make the POST to Raygun, you can see more documentation about that callback here: https://nodejs.org/api/http.html#http_http_request_options_callback
-
 ### Sending request data
 
 You can send the request data in the Send() function, as the fourth parameter. For example:
 ```javascript
-client.send(new Error(), {}, function () {}, request);
+client.send(new Error(), {}, request);
 ```
 
 If you want to filter any of the request data then you can pass in an array of keys to filter when
@@ -139,7 +179,7 @@ const raygunClient = new raygun.Client().init({ apiKey: 'YOUR_API_KEY', filters:
 
 You can add tags to your error in the Send() function, as the fifth parameter. For example:
 ```javascript
-client.send(new Error(), {}, function () {}, {}, ['Custom Tag 1', 'Important Error']);
+client.send(new Error(), {}, {}, ['Custom Tag 1', 'Important Error']);
 ```
 
 Tags can also be set globally using setTags
diff --git a/examples/readme.md b/examples/README.md
similarity index 100%
rename from examples/readme.md
rename to examples/README.md
diff --git a/examples/express-sample/README.md b/examples/express-sample/README.md
new file mode 100644
index 0000000..7774d7d
--- /dev/null
+++ b/examples/express-sample/README.md
@@ -0,0 +1,32 @@
+# Raygun + ExpressJS sample
+
+This is a sample Express application to show how to use Raygun4Node and ExpressJS together.
+
+This example uses the local `raygun4node` package in the project root directory by simply pointing to the root directory as a dependency in package.json:
+
+```
+"raygun": "file:../..",
+```
+
+## Run the sample
+
+First, install the `raygun4node` package.
+
+To do so, navigate to the project root directory, then:
+
+    npm install
+
+Once the package is installed, set your API key in the sample's `config/default.json` and run:
+
+    npm install && npm start
+
+in the subdirectory where you found this README.md file.
+
+## Interesting files to look
+
+- `app.js`
+  - Setup of Raygun (lines 9-12)
+  - Sets the user (lines 27-29)
+  - Attaches Raygun to Express (line 60)
+- `routes/index.js`
+  - Tries to use a fake object, which bounces up to the Express handler (lines 11-15)
diff --git a/examples/express-sample/app.js b/examples/express-sample/app.js
index 3ef9d4a..3b7f0e2 100644
--- a/examples/express-sample/app.js
+++ b/examples/express-sample/app.js
@@ -1,7 +1,9 @@
 var config = require("config");
 
 if (config.Raygun.Key === "YOUR_API_KEY") {
-  console.error("You need to set your Raygun API key in the config file");
+  console.error(
+    `[Raygun4Node-Express-Sample] You need to set your Raygun API key in the config file`,
+  );
   process.exit(1);
 }
 
diff --git a/examples/express-sample/bin/www b/examples/express-sample/bin/www
index 3c51e29..8b88819 100755
--- a/examples/express-sample/bin/www
+++ b/examples/express-sample/bin/www
@@ -65,11 +65,11 @@ function onError(error) {
   // handle specific listen errors with friendly messages
   switch (error.code) {
     case 'EACCES':
-      console.error(bind + ' requires elevated privileges');
+      console.error(`[Raygun4Node-Express-Sample] ` + bind + ` requires elevated privileges`);
       process.exit(1);
       break;
     case 'EADDRINUSE':
-      console.error(bind + ' is already in use');
+      console.error(`[Raygun4Node-Express-Sample] ` + bind + ` is already in use`);
       process.exit(1);
       break;
     default:
diff --git a/examples/express-sample/package-lock.json b/examples/express-sample/package-lock.json
index c70a2f9..89cd721 100644
--- a/examples/express-sample/package-lock.json
+++ b/examples/express-sample/package-lock.json
@@ -22,7 +22,7 @@
     },
     "../..": {
       "name": "raygun",
-      "version": "0.13.2",
+      "version": "0.14.0",
       "dependencies": {
         "@types/express": "^4.17.21",
         "debug": "^4.3.4",
diff --git a/examples/express-sample/package.json b/examples/express-sample/package.json
index d8d249a..3bc8601 100644
--- a/examples/express-sample/package.json
+++ b/examples/express-sample/package.json
@@ -3,7 +3,7 @@
   "version": "0.0.0",
   "private": true,
   "scripts": {
-    "start": "DEBUG=express-sample:server node ./bin/www"
+    "start": "DEBUG=raygun,express-sample:server node ./bin/www"
   },
   "dependencies": {
     "body-parser": "^1.20.2",
diff --git a/examples/express-sample/readme.md b/examples/express-sample/readme.md
deleted file mode 100644
index 307be7b..0000000
--- a/examples/express-sample/readme.md
+++ /dev/null
@@ -1,24 +0,0 @@
-# Raygun + ExpressJS sample
-
-A demo on how to use Raygun4Node and ExpressJS together.
-
-This example uses the `raygun4node` package from the project root directory.
-
-## To run
-
-First, install the `raygun4node` package.
-Navigate to the project root directory, then:
-
-    npm install
-
-Once the package is installed, set your API key in `config/default.json` and run:
-
-    npm install && npm start
-
-## Files to look at 
-
-- `app.js`
-  - Sets the user (line 22)
-  - Attaches Raygun to Express (line 47)
-- `routes/index.js`
-  - Calls a fake object, which bounces up to the Express handler (line 11)
diff --git a/examples/using-domains/readme.md b/examples/using-domains/README.md
similarity index 100%
rename from examples/using-domains/readme.md
rename to examples/using-domains/README.md
diff --git a/examples/using-domains/app.js b/examples/using-domains/app.js
index 1542996..42e1fd7 100644
--- a/examples/using-domains/app.js
+++ b/examples/using-domains/app.js
@@ -1,7 +1,9 @@
 var config = require("config");
 
 if (config.Raygun.Key === "YOUR_API_KEY") {
-  console.error("You need to set your Raygun API key in the config file");
+  console.error(
+    `[Raygun4Node-Domains-Sample] You need to set your Raygun API key in the config file`,
+  );
   process.exit(1);
 }
 
@@ -15,27 +17,30 @@ var appDomain = require("domain").create();
 // Add the error handler so we can pass errors to Raygun when the domain
 // crashes
 appDomain.on("error", function (err) {
-  try {
-    console.log(`Domain error caught: ${err}`);
-    // Try send data to Raygun
-    raygunClient.send(err, {}, function () {
+  console.log(`[Raygun4Node-Domains-Sample] Domain error caught: ${err}`);
+  // Try send data to Raygun
+  raygunClient
+    .send(err)
+    .then((message) => {
       // Exit the process once the error has been sent
-      console.log("Error sent to Raygun, exiting process");
+      console.log(
+        `[Raygun4Node-Domains-Sample] Error sent to Raygun, exiting process`,
+      );
+      process.exit(1);
+    })
+    .catch((error) => {
+      // If there was an error sending to Raygun, log it out and end the process.
+      // Could possibly log out to a text file here
+      console.log(error);
       process.exit(1);
     });
-  } catch (e) {
-    // If there was an error sending to Raygun, log it out and end the process.
-    // Could possibly log out to a text file here
-    console.log(e);
-    process.exit(1);
-  }
 });
 
 // Run the domain
 appDomain.run(function () {
   var fs = require("fs");
 
-  console.log("Running example app");
+  console.log(`[Raygun4Node-Domains-Sample] Running example app`);
 
   // Try and read a file that doesn't exist
   fs.readFile("badfile.json", "utf8", function (err, file) {
diff --git a/lib/raygun.batch.ts b/lib/raygun.batch.ts
index c71ef77..f08d72b 100644
--- a/lib/raygun.batch.ts
+++ b/lib/raygun.batch.ts
@@ -43,6 +43,11 @@ export class RaygunBatchTransport {
     this.httpOptions = options.httpOptions;
   }
 
+  /**
+   * Enqueues send request to batch processor.
+   * Callback in SendOptions is called when the message is eventually processed.
+   * @param options
+   */
   send(options: SendOptions) {
     this.onIncomingMessage({
       serializedMessage: options.message,
@@ -56,7 +61,7 @@ export class RaygunBatchTransport {
 
   stopProcessing() {
     if (this.timerId) {
-      debug("batch transport - stopping");
+      debug(`[raygun.batch.ts] Batch transport - stopping`);
       clearInterval(this.timerId);
 
       this.timerId = null;
@@ -123,7 +128,7 @@ export class RaygunBatchTransport {
     const { payload, messageCount, callbacks } = batch;
 
     debug(
-      `batch transport - processing ( ${messageCount} message(s) in batch)`,
+      `[raygun.batch.ts] Batch transport - processing (${messageCount} message(s) in batch)`,
     );
 
     const batchId = this.batchId;
@@ -137,14 +142,15 @@ export class RaygunBatchTransport {
       const durationInMs = stopTimer();
       if (err) {
         debug(
-          `batch transport - error sending batch (id=${batchId}, duration=${durationInMs}ms): ${err}`,
+          `[raygun.batch.ts] Batch transport - error sending batch (id=${batchId}, duration=${durationInMs}ms): ${err}`,
         );
       } else {
         debug(
-          `batch transport - successfully sent batch (id=${batchId}, duration=${durationInMs}ms)`,
+          `[raygun.batch.ts] Batch transport - successfully sent batch (id=${batchId}, duration=${durationInMs}ms)`,
         );
       }
 
+      // TODO: Callbacks are processed in batch, see how can this be implemented with Promises
       for (const callback of callbacks) {
         if (callback) {
           callVariadicCallback(callback, err, response);
@@ -153,7 +159,7 @@ export class RaygunBatchTransport {
     };
 
     debug(
-      `batch transport - sending batch (id=${batchId}) (${messageCount} messages, ${payload.length} bytes)`,
+      `[raygun.batch.ts] Batch transport - sending batch (id=${batchId}, ${messageCount} messages, ${payload.length} bytes)`,
     );
 
     const stopTimer = startTimer();
diff --git a/lib/raygun.messageBuilder.ts b/lib/raygun.messageBuilder.ts
index b79c5e1..c438e3c 100644
--- a/lib/raygun.messageBuilder.ts
+++ b/lib/raygun.messageBuilder.ts
@@ -31,18 +31,37 @@ type UserMessageData = RawUserData | string | undefined;
 const humanString = require("object-to-human-string");
 const packageDetails = require("../package.json");
 
-function filterKeys(obj: object, filters: string[]): object {
+/**
+ * Filter properties in obj according to provided filters.
+ * Also removes any recursive self-referencing object.
+ * @param obj object to apply filter
+ * @param filters list of keys to filter
+ * @param explored Set that contains already explored nodes, used internally
+ */
+function filterKeys(
+  obj: object,
+  filters: string[],
+  explored: Set<object> | null = null,
+): object {
   if (!obj || !filters || typeof obj !== "object") {
     return obj;
   }
+
+  // create or update the explored set with the incoming object
+  const _explored = explored?.add(obj) || new Set([obj]);
+
   // Make temporary copy of the object to avoid mutating the original
   // Cast to Record<string, object> to enforce type check and avoid using any
   const _obj = { ...obj } as Record<string, object>;
-  Object.keys(obj).forEach(function (i) {
-    if (filters.indexOf(i) > -1) {
-      delete _obj[i];
+
+  Object.keys(obj).forEach(function (key) {
+    // Remove child if:
+    // - the key is in the filter array
+    // - the value is already in the explored Set
+    if (filters.indexOf(key) > -1 || _explored.has(_obj[key])) {
+      delete _obj[key];
     } else {
-      _obj[i] = filterKeys(_obj[i], filters);
+      _obj[key] = filterKeys(_obj[key], filters, _explored);
     }
   });
   return _obj;
diff --git a/lib/raygun.offline.ts b/lib/raygun.offline.ts
index 2782a8e..7680a58 100644
--- a/lib/raygun.offline.ts
+++ b/lib/raygun.offline.ts
@@ -32,6 +32,7 @@ export class OfflineStorage implements IOfflineStorage {
       path.join(this.cachePath, item),
       "utf8",
       (err, cacheContents) => {
+        // TODO: MessageTransport ignores any errors from the send callback, could this be improved?
         this.transport.send(cacheContents);
         fs.unlink(path.join(this.cachePath, item), () => {});
       },
@@ -47,7 +48,7 @@ export class OfflineStorage implements IOfflineStorage {
     this.cacheLimit = offlineStorageOptions.cacheLimit || 100;
 
     debug(
-      `offline storage - initialized (cachePath=${this.cachePath}, cacheLimit=${this.cacheLimit}`,
+      `[raygun.offline.ts] Offline storage - initialized (cachePath=${this.cachePath}, cacheLimit=${this.cacheLimit})`,
     );
 
     if (!fs.existsSync(this.cachePath)) {
@@ -62,23 +63,25 @@ export class OfflineStorage implements IOfflineStorage {
 
     fs.readdir(this.cachePath, (err, files) => {
       if (err) {
-        console.log("[Raygun] Error reading cache folder");
+        console.log(`[Raygun4Node] Error reading cache folder`);
         console.log(err);
         return callback(err);
       }
 
       if (files.length > this.cacheLimit) {
-        console.log("[Raygun] Error cache reached limit");
+        console.log(`[Raygun4Node] Error cache reached limit`);
         return callback(null);
       }
 
       fs.writeFile(filename, transportItem, "utf8", function (err) {
         if (!err) {
-          debug(`offline storage - wrote message to ${filename}`);
+          debug(
+            `[raygun.offline.ts] Offline storage - wrote message to ${filename}`,
+          );
           return callback(null);
         }
 
-        console.log("[Raygun] Error writing to cache folder");
+        console.log(`[Raygun4Node] Error writing to cache folder`);
         console.log(err);
 
         return callback(err);
@@ -95,14 +98,14 @@ export class OfflineStorage implements IOfflineStorage {
   send(callback: (error: Error | null, items?: string[]) => void) {
     this.retrieve((err, items) => {
       if (err) {
-        console.log("[Raygun] Error reading cache folder");
+        console.log(`[Raygun4Node] Error reading cache folder`);
         console.log(err);
         return callback(err);
       }
 
       if (items.length > 0) {
         debug(
-          "offline storage - transporting ${items.length} message(s) from cache",
+          `[raygun.offline.ts] Offline storage - transporting ${items.length} message(s) from cache`,
         );
       }
 
diff --git a/lib/raygun.sync.transport.ts b/lib/raygun.sync.transport.ts
index 15aac77..9ce871c 100644
--- a/lib/raygun.sync.transport.ts
+++ b/lib/raygun.sync.transport.ts
@@ -21,12 +21,19 @@ function syncRequest(httpOptions: SendOptionsWithoutCB) {
   console.log(requestProcess.stdout.toString());
 }
 
+/**
+ * Spawns a synchronous send request.
+ * Errors are not returned and callback is ignored.
+ * Only used to report uncaught exceptions.
+ * @param options
+ */
 export function send(options: SendOptionsWithoutCB) {
   try {
     syncRequest(options);
   } catch (e) {
+    // TODO: Is there a reason we ignore errors here?
     console.log(
-      `Raygun: error ${e} occurred while attempting to send error with message: ${options.message}`,
+      `[Raygun4Node] Error ${e} occurred while attempting to send error with message: ${options.message}`,
     );
   }
 }
diff --git a/lib/raygun.sync.worker.ts b/lib/raygun.sync.worker.ts
index c04715d..8d42b93 100644
--- a/lib/raygun.sync.worker.ts
+++ b/lib/raygun.sync.worker.ts
@@ -13,10 +13,10 @@ transport.send(sendOptions);
 
 function callback(error: Error | null, result: IncomingMessage | null) {
   if (error) {
-    console.log("Error sending with sync transport", error);
+    console.log(`[Raygun4Node] Error sending with sync transport`, error);
   } else {
     console.log(
-      "[raygun-apm] Successfully reported uncaught exception to Raygun",
+      `[Raygun4Node] Successfully reported uncaught exception to Raygun`,
     );
   }
 }
diff --git a/lib/raygun.transport.ts b/lib/raygun.transport.ts
index aa78f49..edc2aee 100644
--- a/lib/raygun.transport.ts
+++ b/lib/raygun.transport.ts
@@ -26,6 +26,12 @@ export function sendBatch(options: SendOptions) {
   return send(options, BATCH_ENDPOINT);
 }
 
+// TODO: Convert this method callbacks to Promise.
+/**
+ * Transport implementation that sends error to Raygun.
+ * Errors are reported back via callback.
+ * @param options
+ */
 export function send(options: SendOptions, path = DEFAULT_ENDPOINT) {
   try {
     const data = Buffer.from(options.message);
@@ -54,7 +60,7 @@ export function send(options: SendOptions, path = DEFAULT_ENDPOINT) {
 
     request.on("error", function (e) {
       console.log(
-        `Raygun: error ${e.message} occurred while attempting to send error with message: ${options.message}`,
+        `[Raygun4Node] Error ${e.message} occurred while attempting to send error with message: ${options.message}`,
       );
 
       // If the callback has two parameters, it should expect an `error` value.
@@ -66,8 +72,9 @@ export function send(options: SendOptions, path = DEFAULT_ENDPOINT) {
     request.write(data);
     request.end();
   } catch (e) {
+    // TODO: Non-HTTP errors are being ignored, should be better pass them up?
     console.log(
-      `Raygun: error ${e} occurred while attempting to send error with message: ${options.message}`,
+      `[Raygun4Node] Error ${e} occurred while attempting to send error with message: ${options.message}`,
     );
   }
 }
diff --git a/lib/raygun.ts b/lib/raygun.ts
index d7552a0..4e96926 100644
--- a/lib/raygun.ts
+++ b/lib/raygun.ts
@@ -99,7 +99,7 @@ class Raygun {
     this._reportColumnNumbers = options.reportColumnNumbers;
     this._innerErrorFieldName = options.innerErrorFieldName || "cause"; // VError function to retrieve inner error;
 
-    debug(`client initialized`);
+    debug(`[raygun.ts] Client initialized`);
 
     if (options.reportUncaughtExceptions) {
       this.reportUncaughtExceptions();
@@ -120,6 +120,7 @@ class Raygun {
     }
 
     this.expressHandler = this.expressHandler.bind(this);
+    this.sendWithCallback = this.sendWithCallback.bind(this);
     this.send = this.send.bind(this);
 
     this._offlineStorage =
@@ -185,10 +186,45 @@ class Raygun {
     return raygunTransport;
   }
 
-  send(
+  /**
+   * Sends exception to Raygun.
+   * @param exception to send.
+   * @param customData to attach to the error report.
+   * @param request custom RequestParams.
+   * @param tags to attach to the error report.
+   * @return IncomingMessage if message was delivered, null if stored, rejected with Error if failed.
+   */
+  async send(
     exception: Error | string,
     customData?: CustomData,
-    callback?: (err: Error | null) => void,
+    request?: RequestParams,
+    tags?: Tag[],
+  ): Promise<IncomingMessage | null> {
+    // Convert internal sendWithCallback implementation to a Promise.
+    return new Promise((resolve, reject) => {
+      this.sendWithCallback(
+        exception,
+        customData,
+        function (err, message) {
+          if (err != null) {
+            reject(err);
+          } else {
+            resolve(message);
+          }
+        },
+        request,
+        tags,
+      );
+    });
+  }
+
+  /**
+   * @deprecated sendWithCallback is a deprecated method. Instead, use send, which supports async/await calls.
+   */
+  sendWithCallback(
+    exception: Error | string,
+    customData?: CustomData,
+    callback?: Callback<IncomingMessage>,
     request?: RequestParams,
     tags?: Tag[],
   ): Message {
@@ -204,7 +240,7 @@ class Raygun {
 
     if (!sendOptionsResult.valid) {
       console.error(
-        `Encountered an error sending an error to Raygun. No API key is configured, please ensure .init is called with api key. See docs for more info.`,
+        `[Raygun4Node] Encountered an error sending an error to Raygun. No API key is configured, please ensure .init() is called with api key. See docs for more info.`,
       );
       return sendOptionsResult.message;
     }
@@ -212,11 +248,14 @@ class Raygun {
     const sendOptions = sendOptionsResult.options;
 
     if (this._isOffline) {
-      this.offlineStorage().save(
-        JSON.stringify(message),
-        callback || emptyCallback,
-      );
+      // make the save callback type compatible with Callback<IncomingMessage>
+      const saveCallback = callback
+        ? (err: Error | null) => callVariadicCallback(callback, err, null)
+        : emptyCallback;
+      this.offlineStorage().save(JSON.stringify(message), saveCallback);
     } else {
+      // Use current transport to send request.
+      // Transport can be batch or default.
       this.transport().send(sendOptions);
     }
 
@@ -234,7 +273,7 @@ class Raygun {
       (major === 13 && minor < 7)
     ) {
       console.log(
-        "[Raygun] Warning: reportUncaughtExceptions requires at least Node v12.17.0 or v13.7.0. Uncaught exceptions will not be automatically reported.",
+        `[Raygun4Node] Warning: reportUncaughtExceptions requires at least Node v12.17.0 or v13.7.0. Uncaught exceptions will not be automatically reported.`,
       );
 
       return;
@@ -245,20 +284,14 @@ class Raygun {
     });
   }
 
-  private sendSync(
-    exception: Error | string,
-    customData?: CustomData,
-    callback?: (err: Error | null) => void,
-    request?: RequestParams,
-    tags?: Tag[],
-  ): void {
-    const result = this.buildSendOptions(
-      exception,
-      customData,
-      callback,
-      request,
-      tags,
-    );
+  /**
+   * Send error using synchronous transport.
+   * Only used to report uncaught exceptions.
+   * @param exception error to report
+   * @private
+   */
+  private sendSync(exception: Error | string): void {
+    const result = this.buildSendOptions(exception);
 
     if (result.valid) {
       raygunSyncTransport.send(result.options);
@@ -285,15 +318,17 @@ class Raygun {
       body: req.body,
     };
 
-    this.send(err, customData || {}, function () {}, requestParams, [
+    this.send(err, customData || {}, requestParams, [
       "UnhandledException",
-    ]);
+    ]).catch((err) => {
+      console.log(`[Raygun] Failed to send Express error: ${err}`);
+    });
     next(err);
   }
 
   stop() {
     if (this._batchTransport) {
-      debug("batch transport stopped");
+      debug(`[raygun.ts] Batch transport stopped`);
       this._batchTransport.stopProcessing();
     }
   }
@@ -365,9 +400,13 @@ class Raygun {
     ) {
       const durationInMs = stopTimer();
       if (error) {
-        debug(`error sending message (duration=${durationInMs}ms): ${error}`);
+        debug(
+          `[raygun.ts] Error sending message (duration=${durationInMs}ms): ${error}`,
+        );
       } else {
-        debug(`successfully sent message (duration=${durationInMs}ms)`);
+        debug(
+          `[raygun.ts] Successfully sent message (duration=${durationInMs}ms)`,
+        );
       }
       if (!callback) {
         return;
@@ -403,6 +442,7 @@ class Raygun {
     };
 
     return {
+      // TODO: MessageTransport ignores any errors from the send callback, could this be improved?
       send(message: string) {
         transport.send({
           message,
diff --git a/lib/types.ts b/lib/types.ts
index a869c6c..3c9ebda 100644
--- a/lib/types.ts
+++ b/lib/types.ts
@@ -68,6 +68,7 @@ export type Tag = string;
 
 export type SendOptions = {
   message: string;
+  // TODO: Remove Callback in SendOptions and use Promises internally
   callback: Callback<IncomingMessage>;
   http: HTTPOptions;
 };
diff --git a/package-lock.json b/package-lock.json
index 0ae0dd4..b319106 100644
--- a/package-lock.json
+++ b/package-lock.json
@@ -1,12 +1,12 @@
 {
   "name": "raygun",
-  "version": "0.14.0",
+  "version": "0.15.0-0",
   "lockfileVersion": 3,
   "requires": true,
   "packages": {
     "": {
       "name": "raygun",
-      "version": "0.14.0",
+      "version": "0.15.0-0",
       "dependencies": {
         "@types/express": "^4.17.21",
         "debug": "^4.3.4",
@@ -15,8 +15,8 @@
         "uuid": "^9.0.1"
       },
       "devDependencies": {
-        "@eslint/js": "^9.1.1",
-        "@types/node": "^20.12.7",
+        "@eslint/js": "^9.2.0",
+        "@types/node": "^20.12.8",
         "@types/stack-trace": "0.0.33",
         "@types/uuid": "^9.0.8",
         "eslint": "^8.57.0",
@@ -29,7 +29,7 @@
         "tap": "^18.7.2",
         "ts-node": "^10.9.2",
         "typescript": "^5.4.5",
-        "typescript-eslint": "^7.7.1",
+        "typescript-eslint": "^7.8.0",
         "verror": "^1.10.1"
       },
       "engines": {
@@ -154,9 +154,9 @@
       }
     },
     "node_modules/@eslint/js": {
-      "version": "9.1.1",
-      "resolved": "https://registry.npmjs.org/@eslint/js/-/js-9.1.1.tgz",
-      "integrity": "sha512-5WoDz3Y19Bg2BnErkZTp0en+c/i9PvgFS7MBe1+m60HjFr0hrphlAGp4yzI7pxpt4xShln4ZyYp4neJm8hmOkQ==",
+      "version": "9.2.0",
+      "resolved": "https://registry.npmjs.org/@eslint/js/-/js-9.2.0.tgz",
+      "integrity": "sha512-ESiIudvhoYni+MdsI8oD7skpprZ89qKocwRM2KEvhhBJ9nl5MRh7BXU5GTod7Mdygq+AUl+QzId6iWJKR/wABA==",
       "dev": true,
       "engines": {
         "node": "^18.18.0 || ^20.9.0 || >=21.1.0"
@@ -1318,9 +1318,9 @@
       "integrity": "sha512-/pyBZWSLD2n0dcHE3hq8s8ZvcETHtEuF+3E7XVt0Ig2nvsVQXdghHVcEkIWjy9A0wKfTn97a/PSDYohKIlnP/w=="
     },
     "node_modules/@types/node": {
-      "version": "20.12.7",
-      "resolved": "https://registry.npmjs.org/@types/node/-/node-20.12.7.tgz",
-      "integrity": "sha512-wq0cICSkRLVaf3UGLMGItu/PtdY7oaXaI/RVU+xliKVOtRna3PRY57ZDfztpDL0n11vfymMUnXv8QwYCO7L1wg==",
+      "version": "20.12.8",
+      "resolved": "https://registry.npmjs.org/@types/node/-/node-20.12.8.tgz",
+      "integrity": "sha512-NU0rJLJnshZWdE/097cdCBbyW1h4hEg0xpovcoAQYHl8dnEyp/NAOiE45pvc+Bd1Dt+2r94v2eGFpQJ4R7g+2w==",
       "dependencies": {
         "undici-types": "~5.26.4"
       }
@@ -1373,16 +1373,16 @@
       "dev": true
     },
     "node_modules/@typescript-eslint/eslint-plugin": {
-      "version": "7.7.1",
-      "resolved": "https://registry.npmjs.org/@typescript-eslint/eslint-plugin/-/eslint-plugin-7.7.1.tgz",
-      "integrity": "sha512-KwfdWXJBOviaBVhxO3p5TJiLpNuh2iyXyjmWN0f1nU87pwyvfS0EmjC6ukQVYVFJd/K1+0NWGPDXiyEyQorn0Q==",
+      "version": "7.8.0",
+      "resolved": "https://registry.npmjs.org/@typescript-eslint/eslint-plugin/-/eslint-plugin-7.8.0.tgz",
+      "integrity": "sha512-gFTT+ezJmkwutUPmB0skOj3GZJtlEGnlssems4AjkVweUPGj7jRwwqg0Hhg7++kPGJqKtTYx+R05Ftww372aIg==",
       "dev": true,
       "dependencies": {
         "@eslint-community/regexpp": "^4.10.0",
-        "@typescript-eslint/scope-manager": "7.7.1",
-        "@typescript-eslint/type-utils": "7.7.1",
-        "@typescript-eslint/utils": "7.7.1",
-        "@typescript-eslint/visitor-keys": "7.7.1",
+        "@typescript-eslint/scope-manager": "7.8.0",
+        "@typescript-eslint/type-utils": "7.8.0",
+        "@typescript-eslint/utils": "7.8.0",
+        "@typescript-eslint/visitor-keys": "7.8.0",
         "debug": "^4.3.4",
         "graphemer": "^1.4.0",
         "ignore": "^5.3.1",
@@ -1408,15 +1408,15 @@
       }
     },
     "node_modules/@typescript-eslint/parser": {
-      "version": "7.7.1",
-      "resolved": "https://registry.npmjs.org/@typescript-eslint/parser/-/parser-7.7.1.tgz",
-      "integrity": "sha512-vmPzBOOtz48F6JAGVS/kZYk4EkXao6iGrD838sp1w3NQQC0W8ry/q641KU4PrG7AKNAf56NOcR8GOpH8l9FPCw==",
+      "version": "7.8.0",
+      "resolved": "https://registry.npmjs.org/@typescript-eslint/parser/-/parser-7.8.0.tgz",
+      "integrity": "sha512-KgKQly1pv0l4ltcftP59uQZCi4HUYswCLbTqVZEJu7uLX8CTLyswqMLqLN+2QFz4jCptqWVV4SB7vdxcH2+0kQ==",
       "dev": true,
       "dependencies": {
-        "@typescript-eslint/scope-manager": "7.7.1",
-        "@typescript-eslint/types": "7.7.1",
-        "@typescript-eslint/typescript-estree": "7.7.1",
-        "@typescript-eslint/visitor-keys": "7.7.1",
+        "@typescript-eslint/scope-manager": "7.8.0",
+        "@typescript-eslint/types": "7.8.0",
+        "@typescript-eslint/typescript-estree": "7.8.0",
+        "@typescript-eslint/visitor-keys": "7.8.0",
         "debug": "^4.3.4"
       },
       "engines": {
@@ -1436,13 +1436,13 @@
       }
     },
     "node_modules/@typescript-eslint/scope-manager": {
-      "version": "7.7.1",
-      "resolved": "https://registry.npmjs.org/@typescript-eslint/scope-manager/-/scope-manager-7.7.1.tgz",
-      "integrity": "sha512-PytBif2SF+9SpEUKynYn5g1RHFddJUcyynGpztX3l/ik7KmZEv19WCMhUBkHXPU9es/VWGD3/zg3wg90+Dh2rA==",
+      "version": "7.8.0",
+      "resolved": "https://registry.npmjs.org/@typescript-eslint/scope-manager/-/scope-manager-7.8.0.tgz",
+      "integrity": "sha512-viEmZ1LmwsGcnr85gIq+FCYI7nO90DVbE37/ll51hjv9aG+YZMb4WDE2fyWpUR4O/UrhGRpYXK/XajcGTk2B8g==",
       "dev": true,
       "dependencies": {
-        "@typescript-eslint/types": "7.7.1",
-        "@typescript-eslint/visitor-keys": "7.7.1"
+        "@typescript-eslint/types": "7.8.0",
+        "@typescript-eslint/visitor-keys": "7.8.0"
       },
       "engines": {
         "node": "^18.18.0 || >=20.0.0"
@@ -1453,13 +1453,13 @@
       }
     },
     "node_modules/@typescript-eslint/type-utils": {
-      "version": "7.7.1",
-      "resolved": "https://registry.npmjs.org/@typescript-eslint/type-utils/-/type-utils-7.7.1.tgz",
-      "integrity": "sha512-ZksJLW3WF7o75zaBPScdW1Gbkwhd/lyeXGf1kQCxJaOeITscoSl0MjynVvCzuV5boUz/3fOI06Lz8La55mu29Q==",
+      "version": "7.8.0",
+      "resolved": "https://registry.npmjs.org/@typescript-eslint/type-utils/-/type-utils-7.8.0.tgz",
+      "integrity": "sha512-H70R3AefQDQpz9mGv13Uhi121FNMh+WEaRqcXTX09YEDky21km4dV1ZXJIp8QjXc4ZaVkXVdohvWDzbnbHDS+A==",
       "dev": true,
       "dependencies": {
-        "@typescript-eslint/typescript-estree": "7.7.1",
-        "@typescript-eslint/utils": "7.7.1",
+        "@typescript-eslint/typescript-estree": "7.8.0",
+        "@typescript-eslint/utils": "7.8.0",
         "debug": "^4.3.4",
         "ts-api-utils": "^1.3.0"
       },
@@ -1480,9 +1480,9 @@
       }
     },
     "node_modules/@typescript-eslint/types": {
-      "version": "7.7.1",
-      "resolved": "https://registry.npmjs.org/@typescript-eslint/types/-/types-7.7.1.tgz",
-      "integrity": "sha512-AmPmnGW1ZLTpWa+/2omPrPfR7BcbUU4oha5VIbSbS1a1Tv966bklvLNXxp3mrbc+P2j4MNOTfDffNsk4o0c6/w==",
+      "version": "7.8.0",
+      "resolved": "https://registry.npmjs.org/@typescript-eslint/types/-/types-7.8.0.tgz",
+      "integrity": "sha512-wf0peJ+ZGlcH+2ZS23aJbOv+ztjeeP8uQ9GgwMJGVLx/Nj9CJt17GWgWWoSmoRVKAX2X+7fzEnAjxdvK2gqCLw==",
       "dev": true,
       "engines": {
         "node": "^18.18.0 || >=20.0.0"
@@ -1493,13 +1493,13 @@
       }
     },
     "node_modules/@typescript-eslint/typescript-estree": {
-      "version": "7.7.1",
-      "resolved": "https://registry.npmjs.org/@typescript-eslint/typescript-estree/-/typescript-estree-7.7.1.tgz",
-      "integrity": "sha512-CXe0JHCXru8Fa36dteXqmH2YxngKJjkQLjxzoj6LYwzZ7qZvgsLSc+eqItCrqIop8Vl2UKoAi0StVWu97FQZIQ==",
+      "version": "7.8.0",
+      "resolved": "https://registry.npmjs.org/@typescript-eslint/typescript-estree/-/typescript-estree-7.8.0.tgz",
+      "integrity": "sha512-5pfUCOwK5yjPaJQNy44prjCwtr981dO8Qo9J9PwYXZ0MosgAbfEMB008dJ5sNo3+/BN6ytBPuSvXUg9SAqB0dg==",
       "dev": true,
       "dependencies": {
-        "@typescript-eslint/types": "7.7.1",
-        "@typescript-eslint/visitor-keys": "7.7.1",
+        "@typescript-eslint/types": "7.8.0",
+        "@typescript-eslint/visitor-keys": "7.8.0",
         "debug": "^4.3.4",
         "globby": "^11.1.0",
         "is-glob": "^4.0.3",
@@ -1545,17 +1545,17 @@
       }
     },
     "node_modules/@typescript-eslint/utils": {
-      "version": "7.7.1",
-      "resolved": "https://registry.npmjs.org/@typescript-eslint/utils/-/utils-7.7.1.tgz",
-      "integrity": "sha512-QUvBxPEaBXf41ZBbaidKICgVL8Hin0p6prQDu6bbetWo39BKbWJxRsErOzMNT1rXvTll+J7ChrbmMCXM9rsvOQ==",
+      "version": "7.8.0",
+      "resolved": "https://registry.npmjs.org/@typescript-eslint/utils/-/utils-7.8.0.tgz",
+      "integrity": "sha512-L0yFqOCflVqXxiZyXrDr80lnahQfSOfc9ELAAZ75sqicqp2i36kEZZGuUymHNFoYOqxRT05up760b4iGsl02nQ==",
       "dev": true,
       "dependencies": {
         "@eslint-community/eslint-utils": "^4.4.0",
         "@types/json-schema": "^7.0.15",
         "@types/semver": "^7.5.8",
-        "@typescript-eslint/scope-manager": "7.7.1",
-        "@typescript-eslint/types": "7.7.1",
-        "@typescript-eslint/typescript-estree": "7.7.1",
+        "@typescript-eslint/scope-manager": "7.8.0",
+        "@typescript-eslint/types": "7.8.0",
+        "@typescript-eslint/typescript-estree": "7.8.0",
         "semver": "^7.6.0"
       },
       "engines": {
@@ -1570,12 +1570,12 @@
       }
     },
     "node_modules/@typescript-eslint/visitor-keys": {
-      "version": "7.7.1",
-      "resolved": "https://registry.npmjs.org/@typescript-eslint/visitor-keys/-/visitor-keys-7.7.1.tgz",
-      "integrity": "sha512-gBL3Eq25uADw1LQ9kVpf3hRM+DWzs0uZknHYK3hq4jcTPqVCClHGDnB6UUUV2SFeBeA4KWHWbbLqmbGcZ4FYbw==",
+      "version": "7.8.0",
+      "resolved": "https://registry.npmjs.org/@typescript-eslint/visitor-keys/-/visitor-keys-7.8.0.tgz",
+      "integrity": "sha512-q4/gibTNBQNA0lGyYQCmWRS5D15n8rXh4QjK3KV+MBPlTYHpfBUT3D3PaPR/HeNiI9W6R7FvlkcGhNyAoP+caA==",
       "dev": true,
       "dependencies": {
-        "@typescript-eslint/types": "7.7.1",
+        "@typescript-eslint/types": "7.8.0",
         "eslint-visitor-keys": "^3.4.3"
       },
       "engines": {
@@ -6593,14 +6593,14 @@
       }
     },
     "node_modules/typescript-eslint": {
-      "version": "7.7.1",
-      "resolved": "https://registry.npmjs.org/typescript-eslint/-/typescript-eslint-7.7.1.tgz",
-      "integrity": "sha512-ykEBfa3xx3odjZy6GRED4SCPrjo0rgHwstLlEgLX4EMEuv7QeIDSmfV+S6Kk+XkbsYn4BDEcPvsci1X26lRpMQ==",
+      "version": "7.8.0",
+      "resolved": "https://registry.npmjs.org/typescript-eslint/-/typescript-eslint-7.8.0.tgz",
+      "integrity": "sha512-sheFG+/D8N/L7gC3WT0Q8sB97Nm573Yfr+vZFzl/4nBdYcmviBPtwGSX9TJ7wpVg28ocerKVOt+k2eGmHzcgVA==",
       "dev": true,
       "dependencies": {
-        "@typescript-eslint/eslint-plugin": "7.7.1",
-        "@typescript-eslint/parser": "7.7.1",
-        "@typescript-eslint/utils": "7.7.1"
+        "@typescript-eslint/eslint-plugin": "7.8.0",
+        "@typescript-eslint/parser": "7.8.0",
+        "@typescript-eslint/utils": "7.8.0"
       },
       "engines": {
         "node": "^18.18.0 || >=20.0.0"
diff --git a/package.json b/package.json
index b94eda4..b1bea88 100644
--- a/package.json
+++ b/package.json
@@ -1,7 +1,7 @@
 {
   "name": "raygun",
   "description": "Raygun package for Node.js, written in TypeScript",
-  "version": "0.14.0",
+  "version": "0.15.0-0",
   "homepage": "https://github.com/MindscapeHQ/raygun4node",
   "author": {
     "name": "Raygun",
@@ -44,8 +44,8 @@
     "test": "tap --node-arg=-r --node-arg=ts-node/register --disable-coverage test/*_test.js"
   },
   "devDependencies": {
-    "@eslint/js": "^9.1.1",
-    "@types/node": "^20.12.7",
+    "@eslint/js": "^9.2.0",
+    "@types/node": "^20.12.8",
     "@types/stack-trace": "0.0.33",
     "@types/uuid": "^9.0.8",
     "eslint": "^8.57.0",
@@ -58,7 +58,7 @@
     "tap": "^18.7.2",
     "ts-node": "^10.9.2",
     "typescript": "^5.4.5",
-    "typescript-eslint": "^7.7.1",
+    "typescript-eslint": "^7.8.0",
     "verror": "^1.10.1"
   },
   "dependencies": {
diff --git a/test/raygun.messageBuilder_test.js b/test/raygun.messageBuilder_test.js
index c8cf3e6..43c2482 100644
--- a/test/raygun.messageBuilder_test.js
+++ b/test/raygun.messageBuilder_test.js
@@ -377,6 +377,10 @@ test("filter keys tests", function (t) {
   });
   var message = builder.build();
 
+  // Original object should not be modified
+  t.equal(body.username, "admin@raygun.io");
+  t.equal(body.password, "nice try");
+
   t.test("form is filtered", function (tt) {
     tt.equal(message.details.request.form.username, undefined);
     tt.equal(message.details.request.form.password, undefined);
@@ -399,6 +403,49 @@ test("filter keys tests", function (t) {
   });
 });
 
+test("avoid infinite recursion in filter method", function (t) {
+  let builder = new MessageBuilder({
+    filters: ["filtered"],
+  });
+
+  // body self-references, causing a potential infinite recursion in the filter method
+  // Causes exception: Maximum call stack size exceeded
+  let body = {
+    key: "value",
+    filtered: true,
+  };
+  // second level self-reference
+  let other = {
+    body: body,
+    filtered: true,
+  };
+  body.myself = body;
+  body.other = other;
+
+  let queryString = {};
+  let headers = {};
+
+  // performs filter on set
+  builder.setRequestDetails({
+    body: body,
+    query: queryString,
+    headers: headers,
+  });
+  var message = builder.build();
+
+  // key is preserved
+  t.equal(message.details.request.form.key, "value");
+  // property in "filters" is filtered
+  t.equal(message.details.request.form.filtered, undefined);
+  t.equal(message.details.request.form.other.filtered, undefined);
+  // self-referencing objects are also not included
+  t.equal(message.details.request.form.myself, undefined);
+  t.equal(message.details.request.form.other.body, undefined);
+
+  // test should finish
+  t.end();
+});
+
 test("custom tags", function (t) {
   t.test("with array", function (tt) {
     var builder = new MessageBuilder();
diff --git a/test/raygun_async_send_test.js b/test/raygun_async_send_test.js
new file mode 100644
index 0000000..3d270c2
--- /dev/null
+++ b/test/raygun_async_send_test.js
@@ -0,0 +1,160 @@
+"use strict";
+
+const test = require("tap").test;
+const VError = require("verror");
+const nock = require("nock");
+const Raygun = require("../lib/raygun.ts");
+
+nock(/.*/)
+  .post(/.*/, function () {
+    return true;
+  })
+  .reply(202, {})
+  .persist();
+const API_KEY = "apikey";
+
+test("async send basic", {}, function (t) {
+  t.plan(1);
+
+  let client = new Raygun.Client().init({
+    apiKey: API_KEY,
+  });
+  client
+    .send(new Error())
+    .then((response) => {
+      t.equal(response.statusCode, 202);
+      t.end();
+    })
+    .catch((err) => {
+      t.fail(err);
+    });
+});
+
+test("async send complex", {}, function (t) {
+  t.plan(1);
+
+  let client = new Raygun.Client()
+    .init({ apiKey: API_KEY })
+    .setUser("callum@mindscape.co.nz")
+    .setVersion("1.0.0.0");
+
+  client
+    .send(new Error())
+    .then((response) => {
+      t.equal(response.statusCode, 202);
+      t.end();
+    })
+    .catch((err) => {
+      t.fail(err);
+    });
+});
+
+test("async send with inner error", {}, function (t) {
+  t.plan(1);
+
+  let error = new Error("Outer");
+  let innerError = new Error("Inner");
+
+  error.cause = function () {
+    return innerError;
+  };
+
+  let client = new Raygun.Client().init({
+    apiKey: API_KEY,
+  });
+  client
+    .send(new Error())
+    .then((response) => {
+      t.equal(response.statusCode, 202);
+      t.end();
+    })
+    .catch((err) => {
+      t.fail(err);
+    });
+});
+
+test("async send with verror", {}, function (t) {
+  t.plan(1);
+
+  let error = new VError(
+    new VError(new VError("Deep Error"), "Inner Error"),
+    "Outer Error",
+  );
+
+  let client = new Raygun.Client().init({
+    apiKey: API_KEY,
+  });
+  client
+    .send(error)
+    .then((response) => {
+      t.equal(response.statusCode, 202);
+      t.end();
+    })
+    .catch((err) => {
+      t.fail(err);
+    });
+});
+
+test("async send with OnBeforeSend", {}, function (t) {
+  t.plan(1);
+
+  let client = new Raygun.Client().init({
+    apiKey: API_KEY,
+  });
+
+  let onBeforeSendCalled = false;
+  client.onBeforeSend(function (payload) {
+    onBeforeSendCalled = true;
+    return payload;
+  });
+
+  client
+    .send(new Error())
+    .then((response) => {
+      t.equal(onBeforeSendCalled, true);
+      t.end();
+    })
+    .catch((err) => {
+      t.fail(err);
+    });
+});
+
+test("check that tags get passed through in async send", {}, function (t) {
+  let tag = ["Test"];
+  let client = new Raygun.Client().init({ apiKey: "TEST" });
+
+  client.setTags(tag);
+
+  client.onBeforeSend(function (payload) {
+    t.same(payload.details.tags, tag);
+    return payload;
+  });
+
+  client
+    .send(new Error())
+    .then((message) => {
+      t.end();
+    })
+    .catch((err) => {
+      t.fail(err);
+    });
+});
+
+test("check that tags get merged", {}, function (t) {
+  let client = new Raygun.Client().init({ apiKey: "TEST" });
+  client.setTags(["Tag1"]);
+
+  client.onBeforeSend(function (payload) {
+    t.same(payload.details.tags, ["Tag1", "Tag2"]);
+    return payload;
+  });
+
+  client
+    .send(new Error(), {}, null, ["Tag2"])
+    .then((message) => {
+      t.end();
+    })
+    .catch((err) => {
+      t.fail(err);
+    });
+});
diff --git a/test/raygun_offline_test.js b/test/raygun_offline_test.js
index aff1cd0..69e058d 100644
--- a/test/raygun_offline_test.js
+++ b/test/raygun_offline_test.js
@@ -17,18 +17,7 @@ test("offline message storage and sending", async function (t) {
     },
   });
   const raygunClient = testEnvironment.client;
-  const send = (e) =>
-    new Promise((resolve, reject) => {
-      raygunClient.send(e, null, (err, data) => {
-        if (err) {
-          reject(err);
-        } else {
-          resolve(data);
-        }
-      });
-    });
-
-  await send(new Error("offline error"));
+  await raygunClient.send(new Error("offline error"));
 
   const files = fs.readdirSync(cachePath);
 
@@ -44,7 +33,7 @@ test("offline message storage and sending", async function (t) {
 
   t.equal(data.details.error.message, "offline error");
 
-  await send(new Error("offline error 2"));
+  await raygunClient.send(new Error("offline error 2"));
 
   await promisify(raygunClient.online.bind(raygunClient))();
   await testEnvironment.nextRequest();
@@ -73,18 +62,7 @@ test("batched offline message storage and sending", async function (t) {
     },
   });
   const raygunClient = testEnvironment.client;
-  const send = (e) =>
-    new Promise((resolve, reject) => {
-      raygunClient.send(e, null, (err, data) => {
-        if (err) {
-          reject(err);
-        } else {
-          resolve(data);
-        }
-      });
-    });
-
-  await send(new Error("offline error"));
+  await raygunClient.send(new Error("offline error"));
 
   const files = fs.readdirSync(cachePath);
 
@@ -100,7 +78,7 @@ test("batched offline message storage and sending", async function (t) {
 
   t.equal(data.details.error.message, "offline error");
 
-  await send(new Error("offline error 2"));
+  await raygunClient.send(new Error("offline error 2"));
 
   await promisify(raygunClient.online.bind(raygunClient))();
   const batch = await testEnvironment.nextBatchRequest();
diff --git a/test/raygun_send_test.js b/test/raygun_send_test.js
index 7ab340b..7fa9a6b 100644
--- a/test/raygun_send_test.js
+++ b/test/raygun_send_test.js
@@ -27,7 +27,7 @@ test("send basic", {}, function (t) {
   var client = new Raygun.Client().init({
     apiKey: API_KEY,
   });
-  client.send(new Error(), {}, function (response) {
+  client.sendWithCallback(new Error(), {}, function (response) {
     t.equal(response.statusCode, 202);
     t.end();
   });
@@ -47,7 +47,7 @@ test("send complex", {}, function (t) {
     .setUser("callum@mindscape.co.nz")
     .setVersion("1.0.0.0");
 
-  client.send(new Error(), {}, function (response) {
+  client.sendWithCallback(new Error(), {}, function (response) {
     t.equal(response.statusCode, 202);
     t.end();
   });
@@ -72,7 +72,7 @@ test("send with inner error", {}, function (t) {
   var client = new Raygun.Client().init({
     apiKey: API_KEY,
   });
-  client.send(error, {}, function (response) {
+  client.sendWithCallback(error, {}, function (response) {
     t.equal(response.statusCode, 202);
     t.end();
   });
@@ -95,7 +95,7 @@ test("send with verror", {}, function (t) {
   var client = new Raygun.Client().init({
     apiKey: API_KEY,
   });
-  client.send(error, {}, function (response) {
+  client.sendWithCallback(error, {}, function (response) {
     t.equal(response.statusCode, 202);
     t.end();
   });
@@ -120,7 +120,7 @@ test("send with OnBeforeSend", {}, function (t) {
     return payload;
   });
 
-  client.send(new Error(), {}, function () {
+  client.sendWithCallback(new Error(), {}, function () {
     t.equal(onBeforeSendCalled, true);
     t.end();
   });
@@ -135,9 +135,9 @@ test("send with expressHandler custom data", function (t) {
   client.expressCustomData = function () {
     return { test: "data" };
   };
-  client._send = client.send;
-  client.send = function (err, data) {
-    client.send = client._send;
+  client._send = client.sendWithCallback;
+  client.sendWithCallback = function (err, data) {
+    client.sendWithCallback = client._send;
     t.equal(data.test, "data");
     t.end();
   };
@@ -155,7 +155,7 @@ test("check that tags get passed through", {}, function (t) {
     return payload;
   });
 
-  client.send(new Error(), {}, function () {
+  client.sendWithCallback(new Error(), {}, function () {
     t.end();
   });
 });
@@ -169,7 +169,7 @@ test("check that tags get merged", {}, function (t) {
     return payload;
   });
 
-  client.send(
+  client.sendWithCallback(
     new Error(),
     {},
     function () {