Repolode
Submit
mintfog

mintfog/sniffy

Open-source, cross-platform packet capture and debugging tool for HTTP/HTTPS, WebSocket, gRPC and SSE traffic.

Open-source alternative to:Charles ProxyFiddler

View on GitHubWebsite
Stars
93
Forks
2
Open issues
1
Last commit
15 hours ago

What is it?

Sniffy is a traffic capture and debugging tool that runs on Windows, macOS and Linux. It records HTTP and HTTPS requests and responses, WebSocket messages in both directions, and streaming sessions such as gRPC and SSE.

It is useful for reproducing HTTP API problems: captured requests can be resent or edited, and mock responses can be returned to check how a client handles them. Breakpoints can pause requests before they leave or responses before they arrive, so data can be changed by hand before continuing.

Behavior can be customized with rules that rewrite content, redirect or block requests, and with JavaScript plugins that can run at request, response, WebSocket and streaming stages. Sessions can be exported as HAR or JSON, and a headless mode exposes a REST API and WebSocket events for server or automated-test use.

Key features

  • 01Inspect HTTP and HTTPS request and response headers and bodies, with search and filters.
  • 02Resend or edit captured requests, and import or copy cURL commands.
  • 03Rewrite content, redirect, block, or return mock responses based on rules.
  • 04Pause traffic at breakpoints to modify data before releasing it.
  • 05View WebSocket messages, gRPC messages and SSE events.
  • 06Extend behavior with in-app JavaScript plugins and export sessions as HAR or JSON.

Use cases

  • Debugging HTTP API issues by replaying or editing captured requests.
  • Testing how a client handles error or mock responses.
  • Inspecting WebSocket or streaming traffic between a client and server.
  • Running a headless proxy on a server for automated testing with its REST API.

Quick start

  1. 1

    Clone the repository

    git clone https://github.com/mintfog/sniffy.git
  2. 2

    Build the frontend

    bash scripts/build.sh frontend
  3. 3

    Start the desktop app in development mode

    go run -tags desktop .

Things to know

  • Building from source requires Go 1.26+, Node.js 22+ and platform-specific desktop dependencies.
  • Linux builds need CGO, GTK 4 and WebKitGTK 6.0, and Windows needs WebView2.

Topics

#packet-capture#http-debugging#https#websocket#proxy#mock-server#debugging

FAQ

What is sniffy?
Open-source, cross-platform packet capture and debugging tool for HTTP/HTTPS, WebSocket, gRPC and SSE traffic. Sniffy is a traffic capture and debugging tool that runs on Windows, macOS and Linux. It records HTTP and HTTPS requests and responses, WebSocket messages in both directions, and streaming sessions such as gRPC and SSE.
Is sniffy free to use? What license does it have?
sniffy is open source under the Apache-2.0 license. Check the license terms before using it in commercial products.
Is sniffy still maintained?
Actively maintained. The last commit to sniffy was on Nov 6, 2026.
What can I use sniffy for?
Debugging HTTP API issues by replaying or editing captured requests. Testing how a client handles error or mock responses. Inspecting WebSocket or streaming traffic between a client and server. Running a headless proxy on a server for automated testing with its REST API.
How do I install sniffy?
Clone the repository: git clone https://github.com/mintfog/sniffy.git Build the frontend: bash scripts/build.sh frontend Start the desktop app in development mode: go run -tags desktop .
Where can I get sniffy?
The source code and installation instructions are on GitHub: https://github.com/mintfog/sniffy

Summary generated by AI from the project's README. GitHub stats refresh daily.

Related projects