Resonance

Resonance is a local-first, zero-account API client application designed to provide an excellent

user experience for testing and interacting with web services. It offers a modern and intuitive

interface for developers with powerful features for API development and testing.

Key Features:

REST/HTTP (HTTP/1.1 and HTTP/2) with all body modes, detailed timing breakdown and cookie display

GraphQL with query and variables editors, schema introspection, an interactive query explorer and subscriptions over WebSocket

gRPC with server reflection, local .proto files, all four RPC kinds and TLS/mTLS

WebSocket, Server-Sent Events and MQTT connections with live status

Import from OpenAPI 3.x, Swagger 2.0, Postman, Insomnia, HAR captures and cURL commands; export to OpenAPI and Postman

Code generation in 9 languages and Markdown/HTML documentation generation

Built-in mock server with response templating, custom bodies, status codes and delays

Pre-request and test scripts in sandboxed JavaScript with a Postman-compatible pm API

Collection runner with data files, request tags, run history and JSON/JUnit XML reports

Response schema validation (JSON Schema drafts 4 to 2020-12) and JSONPath/XPath inspection

Environments with variable templating and dynamic variables

Bearer, Basic, API key, OAuth 2.0 with automatic refresh, Digest, NTLM and AWS Signature v4 authentication

Client certificates (mTLS), keychain-backed secrets and HTTP/HTTPS/SOCKS proxy support

Git-friendly collections stored as plain files, with the current branch shown in the sidebar

Workspace tabs, request history with search and replay, and keyboard shortcuts for everything

Light, dark and system themes with 9 accent colours