Web Sniffers Review: Top HTTP Sniffing Tools Compared

A product page shows a price. You open the page source and the price is not there. Fifteen seconds later, with the Network panel filtered to Fetch/XHR, you are looking at a JSON endpoint that returns the price, the stock count and four fields the page never renders. That is the entire argument for an HTTP sniffer. It moves you from reasoning about what a site probably does to reading what it actually sent.

Three things have changed since this page was first written, and each invalidates part of the older advice. Two of the online sniffers it recommended no longer resolve in DNS. The most-recommended free proxy debugger on Windows stopped being free for work on 3 August 2026, ten days ago. And a growing share of real traffic runs over QUIC, on UDP, where a packet capture shows encrypted datagrams and nothing you can read.

Every version number, price and status below was read from the vendor's own site, documentation or release history on 13 August 2026. Where we could not confirm something, it says so.

What you are actually asking the traffic

Reconnaissance has four questions in it, and a sniffer answers all four.

Which request carries the data. On a modern site the interesting payload is almost never in the document response. It is in an XHR, a GraphQL POST, or a JSON blob inside a <script> tag. Finding it turns a brittle HTML-parsing job into an API-shaped extraction job that survives redesigns.

What the server needs before it will answer. A session cookie, a CSRF token, an Authorization bearer, a signed timestamp, a Referer the endpoint checks. You cannot guess this set. You can read it.

In what order. Redirect chains, token issuance, preflight OPTIONS requests, the login POST that sets three cookies of which only one matters. Sequence is where most half-working scrapers fail.

What the response really is. A 200 containing an error object, an HTML page served with Content-Type: application/json, a gzip body your client silently failed to decode.

Skipping this step has a price you can count. Render the page in a headless browser instead of calling the endpoint behind it and you pay roughly a second of startup and layout per page. One wasted second per page across a ten-thousand-page crawl is close to three hours per run, every run.

A sniffer shows what your browser sent. It does not show what the server concluded about your browser. Those diverge, and the section on fingerprinting is about the gap.

Where a tool sits decides what it can see

Inside the browser. The Network panel sees one browser's requests, fully decrypted, response bodies already decoded and pretty-printed. Nothing from any other process. For front-end and scraping work that is usually the right amount of visibility, and it costs nothing.

On a remote server. Online sniffers fetch a URL for you and print the headers and the source. Nothing of yours is captured, so they are not sniffers in any real sense. They answer one narrow question: what a server returns to a stranger with no cookies from an unfamiliar IP.

At the packet layer. A capture tool reads frames off the interface, so it sees every process on the machine, plus DNS, TCP handshakes, retransmissions, resets and TLS alerts. It is the only category that shows the network rather than the conversation. Encrypted bytes stay encrypted unless you feed it the session keys.

As a proxy in the middle. The tool terminates TLS with its own certificate, so it can show and rewrite everything, set breakpoints, and replay a request with one field changed. Most reconnaissance ends up here, and so do most of the failures.

The tools, category by category

In the browser

The three dead add-ons died together and for one reason. Firefox 57, released 14 November 2017, removed the old extension architecture outright: "Starting in Firefox 57, all support for XPCOM-based add-ons has been removed." Anything not rebuilt as a WebExtension stopped loading that day. Firebug, Live HTTP Headers and HTTPFox never were, and Mozilla has since pulled their listings, so even the "install it in a legacy fork" advice in older round-ups now starts with a 404.

Two DevTools details that cost people hours. Since Chrome 130 the Network panel's HAR export is sanitized by default: Google's documentation states the exported log "will no longer contain Cookie, Set-Cookie, and Authorization headers by default." The menu offers "Save all as HAR (sanitized)" and "Save all as HAR (with sensitive data)" as separate items. Hand a colleague a HAR to reproduce an authenticated request and, unless you picked the second one, you have handed them a log that cannot work. The friendlier detail: Chrome and Edge give a request back as cURL, PowerShell, or fetch, which is the fastest honest way to get a first working request into a scraper. Firefox has an edit-and-resend flow that beats both for iterating on one request.

HTTPWatch is the survivor among the in-browser commercial tools, and it needs a careful look before you download it. Our review predates the current shape of the product: the Firefox and Internet Explorer builds are gone, and version 16.1.8 supports Chrome 105 or later and Edge 105 or later, on Windows only. The free Basic edition is where the trap sits. HttpWatch's own documentation says its detailed functions "are restricted to pages from popular and relevant sites such as amazon.com, ebay.com, google.com, httpwatch.com, microsoft.com", and that "detailed information, such as cookies and headers, will not be available for any other page in HttpWatch Basic Edition." For reconnaissance that inverts the tool: it works on the sites you do not care about. Professional lifts the restriction at $625 for one user, $2,365 for four and $13,285 for a site licence. Write-ups that stop at "basic edition free", this page's previous version included, are describing something you cannot use.

Online sniffers

This is the correction that matters most on this page. The two tools every list of online sniffers still names, this article's earlier version included, are not down for the afternoon. On 13 August 2026, Google Public DNS answers a query for web-sniffer.net with SERVFAIL and the comment "Name servers refused query (lame delegation?)", naming four Route 53 addresses that all return REFUSED. A query for web-sniffer.me returns NXDOMAIN: the name does not exist at the .me registry level. Neither hostname resolves. If you have a bookmark, it is dead.

The .net domain has form. The Webado blog recorded it going offline in June 2014, up for sale, then returning four days later pointed at a spam site. This time the delegation itself is broken rather than repointed.

websniffer.com is the closer replacement, grown into a broader lookup service around the original header checker. Its footer still reads "© 2017 WebSniffer". It sends HTTP/1.0 or HTTP/1.1 and lets you pick a user agent, which is the one thing an online checker does that your browser will not. IPVoid's Web Sniffer does headers plus a body preview, inside a toolbox from NoVirusThanks whose footer carries a 2010-2026 copyright. Note the path: the tool lives at /web-sniffer/, and the /http-sniffer/ URL in older link lists is a 404.

Keep the category in proportion. An online checker tells you what an anonymous request from a datacentre IP gets: useful as a control, useless for anything involving login, cookies or JavaScript.

Packet-level capture

Wireshark is under active maintenance rather than merely alive: 4.6.8 and 4.4.18 shipped on 12 August 2026, the day before this update. The 4.6 branch arrived on 8 October 2025 with a new Plots dialog, compression on live captures, NTP decryption via Network Time Security, and dissection of the process and flow metadata that macOS tcpdump now emits. One line from the 4.6.7 announcement in July 2026 says something about where security work is going: "This release fixes quite a few vulnerabilities. This is due to a recent trend in AI-assisted vulnerability reports." Our Wireshark walkthrough covers the HTTP filters; the caveat that matters for scraping is in the TLS section below.

mitmproxy is the tool most scraping engineers converge on, and 12.2.3 shipped on 12 May 2026. It is the only free option here that reads HTTP/3, and the only one where the interception logic is an ordinary Python file you can put in version control. Read the protocol documentation before relying on that HTTP/3 support: it works in reverse proxy, local and WireGuard modes, client replay is broken, only QUIC version 1 is implemented, and the project states plainly that it "has only been extensively tested with cURL."

NirSoft's WebSiteSniffer needs a flat correction. This page previously listed its HTTPS support as "partial". Its own documentation says otherwise: "WebSiteSniffer cannot capture files of a secured Web site (HTTPS)." Not partial, not with configuration. None.

The other three are archaeology, and how they died is more informative than the fact. IEInspector's site is up and still selling, but its footer copyright ends in 2016 and its design assumes Internet Explorer, which Microsoft retired in June 2022. EffeTech's domain resolves to 216.92.217.183, yet we could not load the product page over HTTP or HTTPS; no working TLS on a network-tools vendor in 2026 is its own answer. HTTP Scoop is the cleanest case: tuffcode.com no longer belongs to its developer and today serves recipes for lemon ricotta pancakes. A resold domain is not a product on hiatus.

Proxy debuggers

Fiddler is the news. On 3 August 2026 Progress Telerik published a new end-user licence agreement for Fiddler Classic whose first substantive sentence is "This Agreement is intended exclusively for Non-Commercial Users. If you are a Commercial User, you are not licensed to use the Software under this Agreement." Commercial users got 45 days, to 17 September 2026, to move to Fiddler Everywhere or stop. The product page describes Classic as being in maintenance mode: "It is not in active development and offers no commitments for releases, patches or tech support." A build shipped the same day the licence changed, version 6.0.20261, so this is licensing rather than abandonment.

Two days later Eric Lawrence, who wrote Fiddler before Telerik acquired it, published his reaction. He wrote that "Progress Telerik has decided to start demanding Fiddler Classic not be used for 'commercial' purposes", called himself "disappointed, somewhat betrayed, but ultimately not surprised", and announced a free, open-source replacement. Its page at clearinet.app lists three items: create the repository, write up the plan, find people to help. Treat it as an intention, not a download. Our older Fiddler review describes a tool that, for anyone doing this work for money, no longer exists on those terms.

Fiddler Everywhere is where Progress wants you, at $7, $13 or $37 per user per month on annual billing, which works out to $84, $156 and $444 a year. Version 8.0.2 landed on 30 July 2026. There is a genuinely free companion, Fiddler Everywhere Reporter: no install, no login, no licence, capturing traffic to a password-protected SAZ file so a non-technical user can send you a log.

Charles is the quiet counterexample, a single-developer tool still shipping and still sold once rather than rented. A licence is $50, a site licence $400, a multi-site licence $700, with per-seat discounts from five seats. Version 5.1 was announced on 21 April 2026 and the download page offers 5.2.1. One correction to our own Charles review and to the round-ups that copy each other: the widely repeated "the trial stops after 30 minutes per session and has no timeline view" appears nowhere on charlesproxy.com that we could find, not on the buy page, the download page or the FAQ. It may well be true. It is not vendor-documented, so we no longer repeat it as if it were.

Proxyman is the usual recommendation for people who want Charles without the Java-era interface, and it runs on five platforms rather than macOS alone. Version 6.12.0 shipped on 28 June 2026. Pricing is perpetual: $89 for one seat, $99 for two, one year of updates included. The free trial is thin on purpose, with a single debugging rule and no mobile apps or WebSocket support.

HTTP Toolkit is the one to try first if setup friction is what usually stops you. It launches an already-intercepted browser, container or emulator instead of asking you to configure a system proxy and install a certificate. The desktop app reached 1.26.1 on 10 June 2026 and the core is open source. The free Hobbyist tier covers interception and inspection; automated rewriting, saved rules and HAR import sit behind Pro. The pricing page renders its figures client-side, so we are not quoting a number we did not read.

Burp Suite and ZAP come from web security rather than web debugging, and both are unmatched at taking one request apart and firing variants of it. Burp Professional is listed at $499 on its product page, which does not state the term; Community is free and covers manual inspection. Both editions are at 2026.7.3, 6 August 2026.

ZAP needs its name corrected. It is not an OWASP project any more. It left on 1 August 2023 for the Software Security Project, and its site now reads "ZAP by Checkmarx" with a note that "ZAP is now supported by Checkmarx and is not part of any foundation." The current release is 2.17.0, announced 15 December 2025. Every article still writing "OWASP ZAP" is three years stale, this page's previous version included.

Two newer entries are worth knowing. Reqable describes itself as "Fiddler + Charles + Postman", runs on Windows, macOS, Linux, Android and iOS, and handles HTTP/1.1, HTTP/2 and HTTP/3. Its Community edition is free and permits commercial use, with limits on cloud devices, stored history and rule sets; Premium is $49.90 a year. Caido is a workbench in the Burp mould whose Basic tier is free forever, capped at two projects, seven workflows and three plugins.

API clients are not sniffers, and they are still part of the loop. Postman, Insomnia and Requestly get used alongside these tools to replay and mutate one request. Requestly was acquired by BrowserStack, announced 6 May 2025, with a commitment that it "continues to be available as an open-source tool". Where cloud accounts are a problem, Bruno is the offline-first answer: there is "no concept of a login or account, and there is no cloud connection or syncing."

Where HTTPS stops being readable

Every category above claims HTTPS support, and the claims mean four different things.

Packet capture and TLS 1.3. Handing Wireshark a server's RSA private key is finished as a technique. The documentation is blunt: it "does not work with TLS 1.3", and it fails on TLS 1.2 too whenever the negotiated suite uses ephemeral Diffie-Hellman, which is now the normal case. What still works is the key log file: point the SSLKEYLOGFILE environment variable at a path before launching the browser, load that file into Wireshark, and the session decrypts. Wireshark's guidance is that "the key log file is generally recommended since it works in all cases." Anything describing TLS decryption as dropping in a .key file was written before 2018.

Proxy interception and pinning. A proxy debugger reads HTTPS by issuing its own certificate and asking your machine to trust its root CA. Fine for browsers on a desktop you control. It fails the moment an application validates the certificate itself, and a pinned app does not produce a readable error. It produces a connection that closes.

Mobile is a separate problem with a hard date. Android's network security configuration stops trusting user-added certificate authorities for apps targeting Android 7.0. Google's documentation states that apps targeting "Android 6.0 (API level 23) and lower also trust the user-added CA store by default", and that is the sentence that stops being true at API 24. Installing your proxy's certificate through the Settings app does nothing for a modern app's traffic. You need the CA in the system store, an emulator image you can write to, or a debug build that opts back in. We have a walkthrough for the Charles certificate on a writable Android image.

Nothing at all. WebSiteSniffer belongs here, with anything else whose HTTPS answer is a workaround rather than a feature.

Four rows in a table can all say "yes" and mean: decrypts by default, decrypts if you export keys, decrypts unless the app checks, and does not decrypt.

What HTTP/3 changed

QUIC runs over UDP and encrypts almost everything a TCP-era tool relied on reading, including the parts of the handshake that used to be in the clear. For packet-level work this is the real break. Open a capture of a modern browsing session and a large share of the interesting traffic is UDP to port 443 that dissects as QUIC and stops there.

The proxy categories dodge the problem, and the dodge has a side effect. Chromium's proxy documentation notes that an HTTPS proxy "may negotiate HTTP/2 (but not QUIC)", and that SOCKSv5 in Chrome "is only used to proxy TCP-based URL requests. It cannot be used to relay UDP traffic." Point a browser at Charles, Fiddler or mitmproxy and it quietly abandons HTTP/3 and speaks TCP to your proxy. That is why proxy debuggers still show you everything.

The side effect is the part nobody mentions. The session you captured through a proxy is not the session the site would have seen. Different protocol, different connection reuse, different multiplexing, different TLS client. Debugging your own application, this costs nothing. Characterising how a target treats a real browser, you have changed the experiment by observing it. When it matters, capture at the packet layer with a key log file and leave the proxy out.

What the sniffer shows is not what gets you blocked

Here is the failure that sends people back to their sniffer a second and third time, convinced they have missed a header.

You copy a request out of DevTools as cURL. It works. You port it to requests or axios, byte for byte identical in method, URL, headers and body. It returns 403. Nothing in the sniffer explains it, because the difference is not in the layer the sniffer shows you.

TLS fingerprinting. Before a single HTTP byte is sent, your client announces a cipher list, an extension list and their ordering in the ClientHello. That combination is stable per client library and differs sharply between Chrome and Python. JA4, the current fingerprinting suite from John Althouse at FoxIO, is BSD-3-Clause licensed and ships as a Wireshark plugin, so you can read your own fingerprint out of a capture rather than theorising about it. An anti-bot service can tell a Chrome ClientHello from a Python one without reading a single header.

Header order and casing. HTTP/1.1 preserves the order you write headers in, and real browsers emit a consistent one. Most HTTP libraries emit a different one, or reorder headers through a dictionary. HTTP/2 lowercases header names, so a request arriving with User-Agent capitalised over an h2 connection is an artefact of tooling.

Protocol-level details. HTTP/2 SETTINGS frame values, window sizes and priority information vary by client and are visible to the server. None of it appears in a DevTools request view.

Sniffing is a beginning. It tells you the semantic content of the request: which endpoint, which parameters, which credentials. Reproducing that faithfully is a separate discipline, and on sites that invest in detecting automated clients it is the discipline that decides whether you get data. Targets that fight back at this layer are where a managed extraction setup earns its cost, because the fingerprint work does not stay solved.

What breaks between one page and ten thousand

Reconnaissance is an act. Crawling is a process. Three things stop scaling.

Capture volume. A HAR of one page load is a few megabytes. Leave a proxy recording a crawl and you are writing gigabytes of JSON no viewer will open, most of it images and fonts. Filter at capture time by host and content type.

The token you copied has a shelf life. Session cookies, CSRF tokens and signed URLs expire. A cURL command lifted from DevTools works for minutes and then does not, which reads exactly like being blocked and is not. Before concluding a site has detected you, re-run the command against a fresh session and see whether the failure follows the token or the client.

Sanitized logs. Chrome's HAR export strips Cookie, Set-Cookie and Authorization by default. If a HAR is your handoff format between reconnaissance and implementation, that default silently removes the three fields the implementation needs most.

The habit that survives contact with production is small. Capture once, write down the endpoint, the exact header set and the sequence in plain text, then check that description against a fresh capture a week later. Build the scraper from the description. The capture is evidence, not documentation.

Corrections to the previous version of this page

• web-sniffer.net and web-sniffer.me were listed as active. Neither resolves in DNS on 13 August 2026: SERVFAIL from refusing nameservers, and NXDOMAIN.
• WebSiteSniffer's HTTPS support was listed as "partial". NirSoft's documentation says it cannot capture HTTPS at all.
• Fiddler Classic was described as free. Since 3 August 2026 it is free for non-commercial use only, with a 17 September deadline for commercial users.
• "OWASP ZAP" was the name used. ZAP left OWASP on 1 August 2023 and the site now reads "ZAP by Checkmarx".
• HTTPWatch was listed as "basic edition free" without qualification. The free edition withholds headers and cookies outside a vendor whitelist.
• The Charles trial was described as limited to 30-minute sessions, and HTTPWatch was credited with HTTP/2 and HTTP/3 support. Neither claim appears on the vendor's own site, so both are gone rather than repeated.

Picking one

• Reading headers or copying a request while scraping. The browser's own Network panel. Free, already installed, already decrypted, and it exports the request in four languages. Use the "with sensitive data" HAR option when the log has to leave your machine.
• Checking what an anonymous visitor gets. websniffer.com or IPVoid's web sniffer. Not the two web-sniffer domains, which no longer exist.
• Traffic from something that is not a browser. mitmproxy first: free, scriptable, speaks HTTP/3. Wireshark when the question is about the network rather than the request, and remember the key log file.
• Breakpoints, rewriting, replaying at speed. Charles at $50 once, Proxyman at $89 once, HTTP Toolkit free for inspection, Reqable for Android and iOS in the same tool.
• Taking one request apart properly. Burp Community, free, or Caido's free tier.
• On Windows, doing this for money, currently on Fiddler Classic. Your licence expires on 17 September 2026. Proxyman, HTTP Toolkit and mitmproxy all run on Windows and all are usable this afternoon.
• Avoid the three dead Firefox add-ons, WebSiteSniffer for anything encrypted, and the three abandoned desktop tools.

The honest answer is boring: DevTools plus mitmproxy covers most of it, and a paid proxy debugger buys ergonomics rather than capability. The hard part was never capturing the request. It is reproducing it.