diff --git a/src/utils/cairoDataTypes/uint256.ts b/src/utils/cairoDataTypes/uint256.ts
index 1c51c4c63..20277a4b9 100644
--- a/src/utils/cairoDataTypes/uint256.ts
+++ b/src/utils/cairoDataTypes/uint256.ts
@@ -133,4 +133,22 @@ export class CairoUint256 {
   toApiRequest() {
     return [CairoFelt(this.low), CairoFelt(this.high)];
   }
+
+  /**
+   * Construct CairoUint256 from calldata
+   * @param calldata Array of two strings representing the low and high parts of a uint256.
+   */
+  static fromCalldata(calldata: [string, string]): CairoUint256 {
+    if (calldata.length !== 2) {
+      throw new Error("Calldata must contain exactly two elements for low and high parts of uint256.");
+    }
+    
+    // Validate each part to ensure they are within the acceptable range.
+    const [low, high] = calldata;
+    const validatedLow = CairoUint256.validateProps(low, UINT_256_LOW_MIN.toString());
+    const validatedHigh = CairoUint256.validateProps(high, UINT_256_HIGH_MIN.toString());
+
+    // Construct a new instance based on the validated low and high parts.
+    return new CairoUint256(validatedLow.low, validatedHigh.high);
+  }
 }
diff --git a/src/utils/calldata/apiDataEncoder.ts b/src/utils/calldata/apiDataEncoder.ts
new file mode 100644
index 000000000..e69de29bb
diff --git a/src/utils/calldata/calldataDecoder.ts b/src/utils/calldata/calldataDecoder.ts
new file mode 100644
index 000000000..ba3f19327
--- /dev/null
+++ b/src/utils/calldata/calldataDecoder.ts
@@ -0,0 +1,78 @@
+import {
+  AbiEntry,
+  AbiEnums,
+  AbiStructs,
+  BigNumberish,
+  ByteArray,
+  CairoEnum,
+  ParsedStruct,
+  Tupled,
+} from '../../types';
+import { CairoUint256 } from '../cairoDataTypes/uint256';
+import { encodeShortString, isText, splitLongString } from '../shortString';
+import { byteArrayFromString } from './byteArray';
+import {
+  felt,
+  getArrayType,
+  isTypeArray,
+  isTypeBytes31,
+  isTypeEnum,
+  isTypeOption,
+  isTypeResult,
+  isTypeStruct,
+  isTypeTuple,
+} from './cairo';
+import {
+  CairoCustomEnum,
+  CairoOption,
+  CairoOptionVariant,
+  CairoResult,
+  CairoResultVariant,
+} from './enum';
+import extractTupleMemberTypes from './tuple';
+
+import { decodeShortString } from '../shortString';
+
+/**
+ * Parse base types
+ * @param type Type from ABI
+ * @param calldata Calldata provided
+ * @returns Parsed value
+ */
+// function decodeBaseType(type: string, calldata: string | string[]): BigNumberish {
+//   switch (true) {
+//     case CairoUint256.isAbiType(type):
+//       // Assuming there exists a method to construct CairoUint256 from calldata
+//       return CairoUint256.fromCalldata(calldata).toBigInt();
+//     case isTypeBytes31(type):
+//       // Assuming a method to decode a short string back from calldata
+//       return decodeShortString(calldata as string);
+//     default:
+//       // Direct conversion for 'felt' types, assuming calldata is a string representing a number
+//       return BigInt(calldata.toString());
+//   }
+// }
+
+function decodeBaseType(type: string, calldata: string | string[]): BigNumberish | CairoUint256 {
+  switch (true) {
+    case CairoUint256.isAbiType(type):
+      // Assuming calldata for CairoUint256 comes as an array of two strings.
+      if (!Array.isArray(calldata) || calldata.length !== 2) {
+        throw new Error("Expected calldata for CairoUint256 as an array of two strings.");
+      }
+      // Use the fromCalldata method to construct and return a CairoUint256 instance.
+      return CairoUint256.fromCalldata([calldata[0], calldata[1]]);
+
+    case isTypeBytes31(type):
+      // Handle decoding for bytes31, which might involve reversing the encoding logic.
+      // Placeholder for actual decoding logic.
+      return decodeShortString(calldata as string);
+
+    default:
+      // Direct conversion for 'felt' types. Ensure calldata is a string.
+      if (typeof calldata !== "string") {
+        throw new Error("Expected string calldata for base type decoding.");
+      }
+      return BigInt(calldata);
+  }
+}