Resonance is a free, open-source API client designed for developing, testing, and debugging web services without cloud accounts. It supports REST, GraphQL, gRPC, WebSocket, Server-Sent Events, and MQTT protocols. Users can create requests, inspect responses, and organize API collections in human-readable YAML files. The software provides authentication tools, environment variables, and secure credential storage through operating system keychains. It includes request scripting, automated tests, mock servers, and schema validation. Developers can import existing API specifications and generate client code in multiple languages. Built with Tauri and Rust, Resonance offers a lightweight, local-first alternative to conventional API testing platforms.
Features
- REST, GraphQL, gRPC, WebSocket, SSE, and MQTT protocol testing
- Local YAML-based API collections with Git-friendly version control
- Pre-request scripting, response assertions, and automated collection testing
- OpenAPI, Postman, Insomnia, HAR, and cURL configuration importing
- Mock servers, response schema validation, and multilingual code generation
- Secure operating system credential storage with headless CLI automation