Best Self Hosted Alternatives to Fiddler Everywhere

Requestly is a local-first API client combined with an HTTP interceptor for capturing, inspecting, and modifying HTTP/HTTPS traffic. It helps developers test APIs, mock backend responses, and override network behavior from a browser extension or desktop app.

Key Features

• REST API client with collections, environments/variables, and request history
• HTTP interception and modification rules for requests and responses
• URL redirects and rewrites (host, query params, map local/remote)
• Modify request/response headers and bodies
• Script injection and resource overriding for web pages
• API mocking with static and dynamic overrides, including GraphQL targeting
• Session recording for capturing and sharing relevant network traffic
• Local workspaces stored on disk, with optional team sync workflows

Use Cases

• Debug and test REST/GraphQL APIs with environment-specific variables
• Mock backend APIs to unblock frontend development and E2E tests
• Redirect traffic between staging/dev/prod endpoints and override scripts/resources

Limitations and Considerations

• Some capabilities depend on where it runs (browser extension vs desktop app) and what traffic can be captured in that environment

Requestly is well-suited for developers who want a Postman-like API client combined with Charles/Fiddler-style interception. It provides practical tooling for request rewriting, API mocking, and repeatable debugging workflows without requiring heavy infrastructure.