Looking for a Fiddler alternative?

HTTP Toolkit is a modern powerful alternative to Fiddler
designed from the ground up for instant targeted debugging and control of any HTTP(S) traffic.

HTTP Toolkit has all the core Fiddler features you use, plus:

  • One-click zero-configuration HTTPS interception: inspect & rewrite HTTPS immediately with no global CA certificate required
  • Targeted interception: automatically capture traffic from just one browser window or from servers and scripts (including Node.js, Python and Ruby) without noise from or interference with the rest of your machine
  • Android integration for apps and mobile browsers, including automated setup, per-app interception, and system-level certificate injection for complete visibility into emulators and rooted devices.
  • Interception internals you can integrate into your own code for mocking, testing or building custom proxies, available as an MIT-licensed open-source library (that's $0 vs the $2,999/year price tag to build on FiddlerCore)
  • Built-in documentation for every standard HTTP header and status code, plus specific endpoint docs & validation for 1400+ popular APIs
  • Flexible rules engine for rewriting traffic so you can combine matchers with mock responses, simulated errors, timeouts, redirection and more
  • One-click transformation of collected traffic into editable rules to match & mock subsequent requests, or to export collected requests as ready-to-use code for 20+ languages

All within a modern beautiful UI, available for Windows, Linux & Mac, and of course 100% open-source.

Intercept

Capture HTTP(S) with zero setup

Automatic setup for targeted interception of HTTP & HTTPS from most clients, including:

For platforms without automatic setup, HTTP Toolkit can be used as an HTTP(S) proxy, compatible with HTTP requests from any language or tool.

HTTP interception for Chrome, Firefox, CLI tools, Docker, Edge, Android and more

Inspect

Explore, search & examine HTTP

Skim through traffic with highlighting by content type, status & source, or search by URL, status and headers to hunt down the messages that matter.

Examine the URL, status, headers & body of each request or response, with inline explanations & docs from MDN.

Dig into message bodies with highlighting & autoformatting for JSON, HTML, JS, hex and others, all using the power of Monaco, the editor from Visual Studio Code.

Inspecting HTTP requests with HTTP Toolkit

Breakpoint

Pause & edit live HTTP traffic

Precisely match requests, jump to them when they appear, and edit anything: the target URL, method, headers or body.

Manually respond directly to requests as they arrive, or pass them upstream, and pause & edit the real response on the way back.

Step through HTTP traffic request by request, or manually mock endpoints and errors.

HTTP debugging with breakpoints on live traffic

Mock

Test with fully automated mock responses Pro

Create rules to match requests and respond with your own content, to quickly prototype against new endpoints or services.

Define new endpoints, override existing ones, or replace external services, to reproduce tricky edge cases and test your error handling.

Import & export your mock rulesets, to build complex setups and share them with your team.

Build HTTP mock rules in just a few clicks

Edit

Rewrite anything

Inject request timeouts, simulate connection failures, and silently redirect requests from one server to another.Pro

Precise matching lets you target the requests you care about. Match any requests sent anywhere by using HTTP Toolkit as a proxy, send requests directly to use it as a mock server.

Match and rewrite HTTP with custom rules

And there's more to come too!

Future plans include security analysis & metrics, session-wide performance graphs & analysis, HTTP client tooling, Docker integration & more...

Sound good? ,
or download now below.

Try it for yourself

100% open-source
Dive in at github.com/httptoolkit
Picture of Tim PerryBuilt in Barcelona
by Tim Perry