Whenever you scrape a site, debug an API, or just want to understand how a page actually talks to its server, an HTTP sniffer is the tool that lets you peek under the hood. It captures the raw conversation between a client and a server — request headers, response headers, cookies, status codes, redirects, POST payloads, and the body content itself — so you can see exactly what is being sent and received instead of guessing.
This post walks through the better-known HTTP/HTTPS sniffers, sorts them into categories, and — because tooling ages fast — marks which ones are still maintained and which have quietly shut down. If you just want the overview, skip ahead to the comparison tables.
What changed since the original write-up. Several long-standing favorites no longer work. Firebug, LiveHTTPHeaders, and HTTPFox all depended on the old Firefox add-on architecture and stopped functioning when Firefox switched to the "Quantum" (WebExtensions) model in 2017. A few standalone Windows/Mac tools have gone years without an update. Where that's the case, it's flagged below, along with the modern replacement.
How sniffers are categorized
Sniffers differ mainly in where they sit in the traffic flow, which determines how much they can see.
1. Browser-based sniffers. These live inside a single browser and only see that browser's traffic. The category used to mean third-party add-ons; today it overwhelmingly means the browser's own built-in developer tools. They're the quickest option for everyday front-end and scraping work, but they can't see traffic from other apps or the system.
2. Online sniffers. Web pages where you paste a URL and the server fetches it for you, then shows you the headers and source. Handy for a fast, install-free check of how a site responds — and for spoofing different user agents — but limited to simple GET-style requests from a remote machine, not your own session.
3. Stand-alone (packet) sniffers. Independent desktop applications that capture traffic at the network/packet level. Because they don't rely on a browser, they can capture traffic from everything on the machine — browsers, native apps, background services. They're the most powerful, but also the most technical, and plain packet capture can't read encrypted HTTPS unless extra steps are taken.
4. Proxy-based debuggers. Tools that insert themselves as a man-in-the-middle proxy between your machine and the internet. By installing their own root certificate, they can decrypt and display HTTPS cleanly, rewrite requests on the fly, set breakpoints, and replay traffic. This is the most popular category today for serious debugging and scraping reconnaissance.
The tables
The tables below are grouped by the four categories above. Each "Read review" link points to the original in-depth review on scraping.pro.
1. Browser-based sniffers
| Tool | Review | Features | HTTPS/SSL | Price | Status & notes |
|---|---|---|---|---|---|
| Browser DevTools (Chrome, Edge, Firefox) — Network panel | — | Full request/response inspection, timing waterfall, cookies, HAR export, throttling, copy-as-cURL | Yes | Free | Active / recommended. Built into every modern browser (open with F12). This is the de-facto replacement for the discontinued add-ons below and where most scraping reconnaissance starts today. |
| HTTPWatch | Read review | Multi-featured, automation, unit-testing support | Yes | Basic edition free | Active. Now a Chrome and Edge extension (the old Firefox/IE versions are gone); supports HTTP/2 and HTTP/3. Its automation API still makes it useful for automated testing. |
| LiveHTTPHeaders | Read review | Headers, cookies, content display | Yes | Free | Discontinued. A lightweight legacy Firefox add-on that stopped working after the Firefox 57 "Quantum" switch (2017). Use the browser's built-in Network panel instead. |
| HTTPFox | Read review | Headers, cookies, content, filtering | Yes | Free | Discontinued. Last release was 0.8.14.1 (May 2014) and it's incompatible with modern Firefox — it only runs on legacy XUL forks such as Waterfox or Pale Moon. |
| Firebug | Read review | Multi-featured developer suite | Yes | Free | Discontinued. The classic add-on was retired in 2017 and its features were folded into Firefox DevTools. Its spirit literally lives on in the built-in tools — but the standalone Firebug is gone. |
2. Online sniffers
| Tool | Review | Features | HTTPS/SSL | Price | Status & notes |
|---|---|---|---|---|---|
| Web-sniffer.net | Read review | HTTP(S) headers and HTML source view, status codes | Yes | Free | Active. A simple, convenient tool for a quick header/redirect check without installing anything. |
| Web-sniffer.me | Read review | HTTP(S) headers, HTML source, download speed, server IP/ISP lookup | Yes | Free | Active. Similar to the above but emulates 20+ user agents and adds basic domain/IP analysis — useful for checking how a site responds to different clients. |
| websniffer.com | — | Request/response headers, status codes, user-agent spoofing | Yes | Free | Active. Another free online header checker; a reasonable alternative if the two above are down. |
| IPVoid Web Sniffer | — | Response headers plus plain-text/HTML content of a remote URL | Yes | Free | Active. Part of a larger toolbox of network/security utilities; handy when you want headers and a content preview. |
3. Stand-alone (packet) sniffers
| Tool | Review | Features | HTTPS/SSL | Price | Status & notes |
|---|---|---|---|---|---|
| Wireshark | Read review | Headers, content, hex view, cookies, full TCP/packet capture across many protocols | Yes | Free (open source) | Active / gold standard. The most powerful general-purpose packet analyzer. Multi-layer protocol capture; can read TLS if you supply session keys. Overkill for simple header peeking, indispensable for deep network debugging. |
| mitmproxy | — | Interactive HTTP(S) interception, replay, modification; scriptable in Python; CLI + web UI | Yes | Free (open source) | Active / recommended. Modern, free, and very popular for scraping work. Installs its own CA cert to decrypt HTTPS, and its Python scripting makes it ideal for automated request capture and rewriting. (Technically a proxy, but commonly grouped with standalone tools.) |
| HTTP Analyzer (IEInspector) | Read review | Multi-featured, automation, timing, content, cookies | Yes | 15-day trial | Effectively abandoned. Last build (v7.6.4) dates to October 2020 and the product is oriented around Internet Explorer, which itself was retired in 2022. Still downloadable, but no longer a forward-looking choice. |
| EffeTech HTTP Sniffer | Read review | TCP packet capture, displays IP addresses | No | 15-day trial | Effectively defunct. Very old, Windows-only, and — critically — has no HTTPS support, which rules it out for almost any modern site. Listed here for historical completeness only. |
| HTTP Scoop | Read review | Headers, cookies, cache, content, hex/text POST data, TCP packets | No (unless a proxy is configured) | 14-day trial | Effectively abandoned. A Mac-only tool whose last release (1.4.3) dates to the OS X 10.x era (~2016); the developer's site (tuffcode.com) is now empty. No timeline view, and no native HTTPS. |
| WebSiteSniffer (NirSoft) | — | Captures and saves all files a browser downloads (HTML, CSS, JS, images) | Partial | Free | Active. A small, free Windows utility focused on harvesting downloaded resources rather than full debugging — useful as a lightweight asset grabber. |
4. Proxy-based debuggers
| Tool | Review | Features | HTTPS/SSL | Price | Status & notes |
|---|---|---|---|---|---|
| Charles Proxy | Read review | Full debugging suite; can re-send requests with configurable iterations and concurrency | Yes | 30-day trial | Active. Cross-platform and well-loved. Note: the unlicensed trial runs only ~30 minutes per session and lacks a timeline view, but it's otherwise fully featured. |
| Fiddler | Read review | Full debugging suite; breakpoints, request editing; add-ons and third-party extensions | Yes | See notes | Active, but split in two. The original is now Fiddler Classic (free, Windows-only). The modern cross-platform version is Fiddler Everywhere (Windows/macOS/Linux, freemium subscription, by Telerik/Progress). Both issue their own root certificate for HTTPS capture. |
| Proxyman | — | Native, polished UI; SSL proxying, domain filtering, breakpoints, scripting | Yes | Freemium | Active. A modern, Charles-like debugger that started on macOS and now also runs on Windows and Linux. A favorite of developers who want a friendlier interface. |
| HTTP Toolkit | — | Automatic interception (browsers, Docker, Android, iOS), inspection, rewriting; built-in client | Yes | Freemium (open source core) | Active / recommended. A modern, cross-platform Fiddler alternative designed for instant, targeted capture with minimal setup. |
| Burp Suite | — | Intercepting proxy plus security scanning, repeater, intruder; large plugin ecosystem | Yes | Community edition free | Active. Security-focused (penetration testing) but its interception features are excellent for understanding complex request flows. The free Community edition covers most manual inspection needs. |
| OWASP ZAP | — | Free intercepting proxy with scanning and fuzzing | Yes | Free (open source) | Active. An open-source security proxy and a solid free alternative to Burp for traffic interception. |
Honorable mentions — API clients. Not sniffers in the strict sense, but Postman, Insomnia, and Requestly are frequently used alongside these tools to capture, replay, and tweak individual requests. Requestly in particular offers a lightweight browser-extension approach for intercepting and modifying traffic.
Picking the right one
A quick rule of thumb:
- Just need to read headers or copy a request while scraping? Start with your browser's DevTools Network panel — it's free, built in, and already shows what you need.
- Want a fast, no-install check of a single URL? Use an online sniffer like web-sniffer.net or web-sniffer.me.
- Need to capture traffic from a non-browser app, or work at the packet level? Reach for Wireshark (deep, technical) or mitmproxy (scriptable, scraping-friendly).
- Doing serious debugging — decrypting HTTPS, setting breakpoints, replaying requests? A proxy debugger like Charles, Fiddler Everywhere, Proxyman, or HTTP Toolkit is the right category.
- Avoid the discontinued add-ons (Firebug, LiveHTTPHeaders, HTTPFox) and the stale standalone tools (IEInspector HTTP Analyzer, EffeTech, HTTP Scoop) — they no longer fit modern, HTTPS-everywhere websites.
This list will grow as more tools are reviewed. Have a sniffer you rely on, or want a particular one covered? Mention it in the comments and share your own experience.