WASM Modules
Mar 21, 2026
10 min read
WebAssembly (WASM) modules extend Mule’s capabilities by allowing you to write custom workflow steps in Go (or other languages that compile to WASM). WASM modules run in a sandboxed environment with access to host functions provided by Mule.
Overview
WASM modules in Mule provide:
- Sandboxed execution - Run custom code safely within workflows
- Host function access - Communicate with the outside world through Mule’s APIs
- JSON I/O - Simple input/output via stdin/stdout using JSON
- Performance - Near-native execution speed
- Portability - Compile once, run anywhere (WASM is platform-independent)
How WASM Modules Work
Input/Output Pattern
WASM modules receive configuration and data via stdin as JSON, process it, and output results to stdout as JSON:
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