diff --git a/README.md b/README.md
index 56192cff..73751933 100644
--- a/README.md
+++ b/README.md
@@ -23,8 +23,42 @@ wget https://github.com/Matts966/zetasql-formatter/releases/latest/download/zeta
 ```
 
 ```bash
-# To apply formatter
-zetasql-formatter [paths]
+# To apply formatter for files
+$ zetasql-formatter [files and directories]
+
+# Format stdin
+$ echo "select * from test" | zetasql-formatter
+SELECT
+  *
+FROM
+  test;
+
+$ zetasql-formatter
+select * from ok;
+-- CTRL-D
+SELECT
+  *
+FROM
+  ok;
+-- CTRL-D
+```
+
+## Integration with [efm-langserver](https://github.com/mattn/efm-langserver)
+
+- Install efm-langserver
+- Locate [`config.yaml`](https://github.com/mattn/efm-langserver#example-for-configyaml) like below
+
+```yaml
+version: 2
+tools:
+  zetasql-formatter: &zetasql-formatter
+    format-command: zetasql-formatter
+    format-stdin: true
+languages:
+  sql:
+    - <<: *zetasql-formatter
+  sql-bigquery:
+    - <<: *zetasql-formatter
 ```
 
 ## License
diff --git a/zetasql/tools/zetasql-formatter/format.cc b/zetasql/tools/zetasql-formatter/format.cc
index 8e94a252..0e3cc2d5 100644
--- a/zetasql/tools/zetasql-formatter/format.cc
+++ b/zetasql/tools/zetasql-formatter/format.cc
@@ -1,4 +1,5 @@
 #include <iostream>
+#include <iterator>
 #include <string>
 #include <vector>
 #include <fstream>
@@ -43,7 +44,15 @@ int main(int argc, char* argv[]) {
   gflags::SetVersionString(ZSQL_FMT_VERSION_STRING);
   gflags::ParseCommandLineFlags(&argc, &argv, true);
   if (argc <= 1) {
-    std::cerr << kUsage << std::endl;
+    std::istreambuf_iterator<char> begin(std::cin), end;
+    std::string sql(begin, end);
+    std::string formatted;
+    const absl::Status status = zetasql::FormatSql(sql, &formatted);
+    if (status.ok()) {
+      std::cout << formatted;
+      return 0;
+    }
+    std::cerr << "ERROR: " << status << std::endl;
     return 1;
   }
   std::vector<std::string> remaining_args(argv + 1, argv + argc);