Network Interceptor

About

Network Interceptor gives developers full control over network requests
  directly in the browser. Set up rules to mock, redirect, block, delay,
  or modify requests — without touching your backend or configuring a proxy.

  ── RULE TYPES ──────────────────────────────────────────

    Mock          Return a custom response body and status code for any
                  fetch or XHR request.

    Redirect      Transparently forward a request to a different URL,                                                                                                                        
                  preserving the original method and headers.
                                                                                                                                                                                             
    Block         Cancel matching requests outright.                                                                                                                                       

    Delay         Slow down requests by a configurable number of
                  milliseconds to simulate latency.

    Modify Headers  Add, set, or remove request and response headers
                    on matching requests.

    Modify Query Params  Add, replace, or remove URL query parameters
                         without editing your source code.

    Redirect JS   Serve a local or alternate script in place of a
                  remote JavaScript file.

  ── MATCHING OPTIONS ────────────────────────────────────

    Match URLs by exact string, contains, wildcard (*), or full regex.
    Filter by HTTP method (GET, POST, PUT, DELETE, etc.) or match any.

  ── HOW IT WORKS ────────────────────────────────────────

    Rules are applied in real time — no page reload required after
    toggling. A subtle on-page toast shows which rules fired and
    against which URL, so you always know what was intercepted.

  ── USE CASES ───────────────────────────────────────────

    • Mock API responses during frontend development
    • Test error states (404, 500) without backend support
    • Simulate slow network conditions
    • Override feature flags or A/B test payloads
    • Strip or inject authentication headers
    • Redirect production API calls to a local dev server

  No external servers. No data leaves your browser.