03Network traffic analyzer for Chrome
See every network request your browser makes.
NetSniffer captures every HTTP request, response, and WebSocket frame in a Wireshark-style side panel — inspect, decode, replay, and mock traffic without leaving the tab. Free, no account, 100% on your device.
No account, no sign-up — capture and analysis run entirely on your device.
(01)Features
A full network workbench in the side panel.
Live capture of every request
NetSniffer taps the DevTools protocol to record every HTTP request, response, and WebSocket frame the page makes — in real time, in a panel beside the tab you are watching.
Deep packet inspector
Open any request to read its headers, query params, request body, response, cookies, timing waterfall, and a security tab — the detail you would dig for in DevTools, organized for reading.
Smart decode built in
JWTs are unpacked into claims, JSON is folded into a tree, form and URL-encoded bodies are parsed, and an entropy view flags encrypted or random payloads — no copy-pasting into other tools.
Replay and a real API client
Resend any captured request, tweak its headers or body first, or build one from scratch in the API client. Copy any request as cURL or fetch to take it elsewhere.
Mock responses on the fly
Define rules that intercept matching requests and return your own status, headers, and body — test error states and edge cases without touching the backend.
Visualize the traffic
A bandwidth chart, request waterfall, domain treemap, and error sparkline turn the raw stream into a picture of what is slow, heavy, or failing.
(02)How it works
From capture to insight in three steps.
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1
Open the side panel
Click the NetSniffer icon on any tab to open the analyzer beside the page. There is no account and nothing to set up.
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2
Capture as you browse
Use the page normally. Every request, response, and WebSocket frame streams into the list live — filter by method, status, domain, or text.
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3
Inspect, replay, or mock
Open a request to decode it, resend or edit it in the API client, or write a mock rule — then export a report or copy any request as cURL.
(03)Privacy
Your traffic is analyzed on your device — never ours.
- Capture and analysis run entirely in your browser using the DevTools debugger API — no traffic is ever sent to a server of ours.
- No accounts, no telemetry, no analytics, and no remote code.
- Captured traffic lives in memory in the panel and is written to disk only when you choose to export a report or HAR.
- Least-privilege by design: capture attaches only to the tab you open it on, and only while the panel is open.
(04)FAQ
Questions, answered.
Does NetSniffer send my traffic anywhere?
No. Capture and analysis run entirely on your device using the DevTools debugger API. NetSniffer has no servers, no telemetry, and no analytics — your traffic never leaves your browser.
How is this different from Chrome's DevTools Network tab?
NetSniffer lives in a side panel so it stays open beside the page, and it adds tools DevTools does not: a built-in API client and request replay, response mocking, JWT/JSON/entropy decoders, traffic visualizations, and one-click export or copy-as-cURL.
Why does Chrome show a "started debugging this browser" banner?
NetSniffer captures traffic through the Chrome DevTools protocol, which requires the debugger permission — so Chrome shows its standard yellow banner while capture is active. It disappears the moment you stop capturing or close the panel.
Can I replay or edit a request?
Yes. Resend any captured request as-is, edit its headers or body first, or compose a new one in the built-in API client. You can also copy any request as a cURL command or fetch call.
Can I mock or override responses?
Yes. Define mock rules that match by URL or method and return your own status, headers, and body — useful for testing error states and edge cases without changing the backend.
Does it capture WebSocket traffic?
Yes. WebSocket connections and their frames are captured alongside HTTP requests, so you can inspect real-time messages in the same panel.
Which browsers are supported?
Chrome and other Chromium browsers (Edge, Brave, Arc) on Manifest V3. Firefox and Safari aren't supported, since NetSniffer relies on the Chrome DevTools protocol.