The best Wappalyzer alternatives depend on whether you want to check one site or find many. Single-site lookups and browser extensions tell you what a page runs on, source code search engines find every site using a script, web surveys track usage across the internet, and lead databases list sites by technology. Ten tools follow in no particular order.
You land on a well-built website and want to know what's under the bonnet: the CMS, the analytics, the chat widget, the shop platform. Wappalyzer is the name most people reach for, but it's far from the only way to find out.
Wappalyzer itself isn't in this list, and the same ten tools answer the search for BuiltWith alternatives too, with that tool included as one entry. They're listed alphabetically and in no particular order, and each description comes from the tool's own website, read as of Nov 2026.
Tech stack lookup tools compared
| Tool | Type | Good for |
|---|---|---|
| BuiltWith | Technology lookup and lead lists | Lookups, usage trends and lists of sites |
| DetectZeStack | Tech stack API | Developers who need lookups in code |
| NerdyData | Source code search engine | Finding every site using a piece of code |
| Netcraft | Site report tool | The infrastructure behind a single site |
| PublicWWW | Source code search engine | Searching HTML, JavaScript and CSS across the web |
| TechLookup | Website tool detection | Spotting the CRM, shop system and plugins |
| TechnologyChecker | Tech stack lookup and lists | Full stack lookups and lists by technology |
| W3Techs | Web technology survey | Usage statistics across the whole web |
| WhatCMS | CMS and technology detector | Identifying which CMS a site uses |
| WhatRuns | Browser extension | One-click checks while you browse |
Ten ways to see what a website runs on
BuiltWith
Best for: Sales teams and analysts who want lookups, weekly technology usage trends and free lead lists of sites using a given technology.
DetectZeStack
Best for: Developers who'd rather call an API, with change monitoring and competitor comparisons, plus free single-URL checks that need no signup.
NerdyData
Best for: Finding every website that uses a given script or piece of HTML, then building prospect lists or sizing a market from the results.
Netcraft
Best for: A quick look at the infrastructure and technologies behind one site, drawn from the company's internet data mining.
PublicWWW
Best for: Researchers searching page source for any snippet, such as an analytics ID or theme folder, with results sorted by website popularity.
TechLookup
Best for: Seeing the shop system, CRM, support chat, payment provider and marketing tools any website uses, with an API and bulk domain uploads.
TechnologyChecker
Best for: Entering a domain to see its full tech stack, with a browser extension and searches across business domains by the technologies they run.
W3Techs
Best for: Analysts and writers who want web technology usage surveys rather than a single-site lookup, from a team with no ties to the vendors it covers.
WhatCMS
Best for: Identifying a site's CMS, plus sister tools that detect hosting providers, WordPress themes and Shopify themes.
WhatRuns
Best for: Checking any page you're on with one click from a free browser extension, with alerts when a site starts or stops using a technology.
Type a URL, search the source, or survey the web?
Here's what most Wappalyzer users don't expect: only a few of these tools work the way it does, where you type a URL and read the result. Netcraft's page asks 'What's that site running?', WhatCMS says it 'detects over 1,200 CMS & website powering technologies' (the vendor's own count), TechLookup promises 'See what tools any website uses', and WhatRuns is 'A free browser extension that helps you identify technologies used on any website'.
Others search the code of huge numbers of pages at once. PublicWWW is a 'Source Code Search Engine' and NerdyData offers to 'Find every website using any HTML code'. Ask either one for a tracking script or a theme name and you get back a list of sites, not a report on one.
Want AI doing the heavy lifting in your marketing?
I build the systems that handle the boring 80 percent, so you get your week back. Done properly, with the human kept in.
W3Techs is different again: it 'provides information about the usage of various types of technologies on the web', so it tells you how popular a technology is, not who uses it. DetectZeStack is a 'Tech stack intelligence API' for developers, and TechnologyChecker calls itself a 'website technology checker & tech stack lookup'. Two of the lookup services here also pitch lists of sites by the technology they use, which makes them sales tools as much as research ones.
Matching the tool to the job
- Checking a competitor's site. A single-site lookup or a browser extension answers it in seconds.
- Finding prospects. Sales teams want lists of sites using a technology, which lead-list tools and source code search engines both produce.
- Writing about trends. A web survey shows how common a CMS or analytics tool is across the web.
- Building lookups into your own product. An API lets you run them in code and store the results.
- Checking your own site. A lookup also shows what your site reveals to everyone else, such as version numbers and scripts you forgot you'd added.
Why two lookups can disagree
Detection tools read what a page sends to the browser: HTML, scripts, headers and cookies. Anything that runs only on the server, or loads after a login, can be invisible to them, and a site that hides version numbers gives less away. One tool in this list makes that point itself, noting that a browser extension only sees what loads in your browser on the page you have open. So if two tools give different answers, both may be right about what they could see.
If you're using these for competitor research, my guides to using an SEO spy tool and what a website spy tool does cover the marketing side.
Five questions before you pick a lookup tool
- Do I need one site at a time, or lists of many sites?
- Will I check sites by hand, in the browser, or through an API?
- Do I need history, such as when a site added or dropped a tool?
- Do I need company details, or only the technology?
- How many lookups will I run each month?
Do you make a website technology lookup tool? Tool makers can ask to be considered for a featured place on this list.
My advice for picking a Wappalyzer replacement
Decide whether you're looking at one site or hunting for many. For one site, a lookup page or a free browser extension does the job, and you'll know within a minute whether you like it. For lists of sites, try a source code search engine first, because it shows you exactly which code it matched, then move to a lead-list tool if you need company details alongside. Developers should start with an API's free requests before building anything on top of it.
Want your tool on this list? Featured spots and reviews here are paid partnerships. Here's how to partner with me.
Frequently asked questions
What is the best free alternative to Wappalyzer?
Several tools here name a free option on their own pages, as of Nov 2026, including a free browser extension, free single-URL checks and free source code search results. Which suits you depends on whether you check one site or many.
How do tech stack lookup tools work?
They read what a website sends to your browser, such as HTML, scripts, headers and cookies, and match it against the fingerprints of known technologies. Anything that runs only on the server may not show up.
Can I find every site that uses a particular tool?
Yes, with a source code search engine or a lead-list tool. You search for a technology or a snippet of code and get back a list of sites using it.
Are tech lookup tools accurate?
They're as accurate as what a site reveals. Hidden version numbers, server-side code and pages behind a login can all be missed, so two tools can give different answers for the same site.
Can I check a site from my browser?
Yes. A browser extension shows the technologies on the page you're viewing with one click, though it only sees what loads in your browser.
What's the difference between a lookup tool and a web technology survey?
A lookup tool tells you what one site runs on. A survey tells you how widely a technology is used across the web, without listing every site that uses it.
