Web Debugger

Inspect and modify HTTP traffic: breakpoints, proxy rules, a scripting engine and full request and response inspection.

Intercept and inspect HTTP traffic

Record HTTP, HTTPS and WebSocket traffic as it flows through the proxy. Every entry lands in a colour-coded list with status, timing and size, above a waterfall of the whole session. Select a row and the inspector breaks it down: headers, body, per-host request counts, and a phase-by-phase timing breakdown from DNS lookup to content download.

Live capture of HTTP, HTTPS and WebSocket traffic
Session waterfall with per-request timing phases
Roll-ups by host, status code and content type

Captured HTTP entries with status, time and size columns beside the inspector's timing waterfall and phase breakdown for a selected request

Network call graph showing captured requests branching from the root document across hosts — The Network tab draws captured traffic as a call graph, so you can see how requests fan out across hosts.

Performance analysis across the session

The Performance tab rolls the whole session into one read: Page Vitals for request count, time to first byte and total weight, an error summary of 4xx, 5xx and failed requests, and hotspot lists of the slowest requests, largest responses and redirect chains. Every row is clickable and opens the request behind the number. It works for live recordings and imported HAR files alike.

Page vitals, error summary and hotspot lists
Caching, compression and third-party weight breakdowns
Click any metric to open the request behind it

Performance overview with page vitals, error summary, slowest requests, largest responses and redirect chains

Rewrite traffic automatically with rules

Rules modify matching requests and responses without pausing anything: strip a header on every call, rewrite a status code for a host, or return a canned response for an endpoint. Match conditions combine with AND and OR, and the actions you pick stack into an ordered pipeline drawn from five categories: request modifications, response modifications, flow control, display and marking, and final actions.

Match conditions combined with AND and OR
Actions for URLs, headers, bodies, cookies and status codes
Delays, bandwidth throttling and triggered breakpoints

The rule editor with a URL match condition, the action palette grouped into request, response and flow control categories, and an Update Status Code action in the pipeline

Pause and edit requests with breakpoints

A breakpoint holds a matching request on the wire before it reaches the server, or a response before it reaches the client. The paused exchange opens as editable rows for params, headers, cookies and body, and once you change anything the Forward button switches to Forward Modified, so it is always clear whether the original or your version goes out. Drop discards the request entirely.

Pause before the request or after the response
Edit params, headers, cookies and body inline
Forward the original, forward your changes, or drop it

A paused request held by a breakpoint, with its params, headers and cookies listed as editable rows next to Drop and Forward buttons

Script the proxy in JavaScript

When rules cannot express the logic, write it. A script declares onRequest and onResponse functions that run on matched traffic, in an editor with syntax highlighting and autocomplete for the built-in APIs. Return the modified object and the proxy uses your version from that point on, while the console panel underneath streams whatever the script logs as traffic flows.

onRequest and onResponse hooks on matched traffic
$http, $env and console APIs built in
Live console output as scripts run

The script editor showing onRequest and onResponse functions with syntax highlighting, above the console panel for script output

The Composer tab replaying a PUT request with editable headers, cookies and a JSON body beside the captured entries list — Composer resends any captured request with your edits. Replays run through the proxy like normal traffic, so rules, scripts and breakpoints fire on them too.

Capture from browsers, terminals and remote devices

Choose how traffic reaches the proxy from a single dropdown: an explicit proxy port any client can point at, an instrumented browser window launched straight from the app, a terminal with the proxy environment already set, or a phone on your network paired via QR code. Map Remote redirects a host or URL to another host, Map Local serves URLs from a directory on disk, and sessions import and export as standard HAR files.

Explicit proxy, browser, terminal and remote device capture
Map Remote and Map Local for redirecting requests
HAR import and export, plus CSV export of request metadata

The capture source dropdown open with Explicit Proxy, Browser, Terminal and Remote Device options above the HAR file dropzone

Try the reading half in your browser

The parts of the Web Debugger that read a capture, the entries grid, the request and response detail panel and the waterfall timeline, run in the browser as a free HAR viewer. Drop in a .har file to see the same interface before you install anything. Capture, breakpoints, rules and scripting need the local proxy, so those stay in the desktop app.

Open the free HAR viewer