Resonance is a clean and minimal 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:

• Import collections from OpenAPI 3.0 specifications and Postman collections
• Environment management with variable templating for different deployment contexts
• Multiple authentication methods including Bearer tokens, Basic Auth, API keys, OAuth 2.0, and Digest authentication
• Generate code in 9 languages: cURL, Python, JavaScript, Node.js, Go, PHP, Ruby, and Java
• GraphQL support with dedicated query editor and syntax highlighting
• Built-in mock server for testing without a backend, with custom responses and configurable delays
• Workspace tabs for managing multiple concurrent requests with independent state
• Request history with search and replay capability for easy debugging
• Performance metrics showing detailed timing breakdown including DNS, TCP, TLS, and download times
• Cookie management with full attribute display
• HTTP proxy support with authentication and bypass lists
• Protocol version control supporting HTTP/1.1, HTTP/2, and HTTP/3
• Comprehensive keyboard shortcuts for efficient workflow
• Four theme options: light, dark, system-adaptive, and blueprint
• Available in English, German, Spanish, French, and Italian