See inside your HTTP and HTTPS traffic.
VioLens is a debugging proxy for Windows and macOS. Capture the requests your browsers and apps make, read them, change them, and send them again. It picks up where Fiddler Classic left off, and it's free for any use.
Preview releases for 64-bit Windows 10 and 11, and for macOS 11 or later on Apple silicon (still being tested).
| # | Status | Method | URL | Resp | Waterfall |
|---|---|---|---|---|---|
| 41 | 200 | GET | https://shop.example.com/ | 18.2 KB | |
| 42 | 200 | GET | https://cdn.example.com/app.3f9c.js | 212 KB | |
| 43 | 401 | POST | https://api.example.com/v2/session | 96 B | |
| 44 | 302 | GET | https://login.example.com/authorize?client_id=web | 0 B | |
| 45 | 200 | POST | https://api.example.com/v2/session | 1.4 KB | |
| 46 | 200 | GET | https://cdn.example.com/hero.webp | 88.0 KB | |
| 47 | 502 | GET | https://metrics.example.net/collect | 612 B |
An illustration of the session list, with the waterfall showing each request's DNS lookup, connection, TLS handshake, wait and download.
Everything you need to debug the web
Point a browser, an app or a phone at VioLens and every request shows up in the list, decrypted and decompressed, ready to read.
HTTPS and plain HTTP
Decrypts HTTPS with a root certificate made on your own machine. It becomes the system proxy while it runs, and puts your settings back when it stops.
Readable requests and responses
Headers, Raw, JSON, WebForms, images, Hex and Cookies views, and every message on a WebSocket. Bodies compressed with gzip, deflate, Brotli or zstd are decompressed for you.
Breakpoints and AutoResponder
Pause a request or response, edit it, then let it go on. Or answer requests with your own files, redirects, delays and errors before they reach the server.
Composer and Replay
Write a request from scratch, or edit a captured one, and send it, binary bodies included, byte for byte. Press R to send the selected request again.
Timing like your browser's tools
A waterfall of every request's phases, a Timing tab for each one, and Statistics: bytes, compression savings, slowest requests and easy wins.
Find, Compare and TextWizard
Search inside bodies, compare two sessions side by side, and decode Base64, URL encoding, JWTs and more.
QuickExec, scripts and extensions
Type QuickExec commands like ?login or bpu /api. Load a CustomRules.js-style script to change traffic as it passes, or add .NET extensions.
Works on real networks
Goes through your company's proxy, including PAC scripts and sign-in, and shows when a server asks for a client certificate. Captures phones too, and opens and saves SAZ and HAR files.
Coming from Fiddler Classic?
VioLens aims to feel familiar, while catching up with how the web has changed since Fiddler Classic's last big updates.
What carries over
- Your .saz files open as they are, and VioLens saves them too.
- FiddlerScript: OnBeforeRequest, OnBeforeResponse, Rules menu options, context actions and columns.
- Extensions port from their source with few changes; three ported extensions come with the installers.
- Familiar tools: breakpoints, AutoResponder rules, Composer, Replay, Find, TextWizard and the QuickExec command box.
What's new
- Timing shown the way browsers' developer tools show it.
- Compare built in, with no separate diff program to install.
- WebSocket messages, live, with compressed and fragmented messages put back together.
- HAR import and export, zstd and Brotli, and cookie warnings for today's browser rules.
- macOS as well as Windows, built on .NET 10 and Avalonia.
Free for any use, now and later
VioLens is MIT licensed and built in the open. Try the preview, report what breaks, or help build it.