BuiltWith and Wappalyzer Alternatives: Website Technology Lookup Tools (2026)

Looking up what a website is built with used to be a developer’s party trick. Now it is a sales motion. If you sell websites, ads, automation or any agency service, the stack a prospect runs, and the tools it is obviously missing, is one of the fastest ways to decide whether a business is worth a call and what to say when you make it.

The catch is that “look up a website technology stack” is not one job. It is at least three. Sometimes you want an instant read on one site you are looking at. Sometimes you want a list of every site running a given platform. And sometimes you want to take detection from a single lookup to a filtered, prioritized outreach list. Different tools win at each, and the free tiers vary from genuinely useful to barely a teaser.

This is a comparison of nine ways to do it, grouped by the job they actually do. Pricing changes constantly and most of these tools gate their best data, so treat any specific number or plan as something to confirm on the vendor’s own site before you rely on it. Where a tool is free, that is called out plainly. Where the real value is paid, that is called out too.

The instant detectors: browser extensions#

These are the tools you reach for when you are already looking at a site and want to know what it runs right now. They are fast, mostly free, and work one page at a time.

1. Wappalyzer#

Wappalyzer is the reference point for in-browser detection, and it earns it. It runs as a browser extension and as a website lookup. Open any page, click the icon, and it lists the CMS, ecommerce platform, analytics, ad tags, frameworks, hosting and more, read straight from the code the page already serves. The fingerprint library is large and well maintained, which is the part you cannot easily replicate by hand.

The free extension covers single-site lookups well. The paid layer is where bulk lookups, technology lists (“show me sites using X”), lead lists and contact enrichment live, and those plans are a real purchase decision rather than a token upsell. For per-site reads while you browse, the free tier is usually enough. Confirm current pricing on Wappalyzer’s site before you commit to anything heavier.

2. WhatRuns#

WhatRuns is the lighter-weight companion in this category. It is a free browser extension that, on click, surfaces the technologies behind a page: CMS, analytics, widgets, frameworks, fonts and hosting, with a clean and readable panel. It is a fast second opinion, and running it alongside Wappalyzer is a reasonable habit, since no single fingerprint set catches everything.

Its coverage can be thinner than Wappalyzer’s on more obscure tools, and the heavier monitoring and alerting features sit behind an account or paid plan. As a free, instant, one-page detector, though, it does the job and adds very little friction.

The honest limit on both extensions is the same. They read client-side fingerprints, the code served to the browser, extremely well, and they hit a wall on server-side, headless or heavily proxied stacks that do not expose those tells. A blank result means “not detected”, not “not present”, and the better tools are careful about that distinction.

The database players: lists and history#

The second job is the inverse of the first. Instead of “what does this one site run”, you are asking “which sites run this thing”, or “what did this site run two years ago”. That needs a crawled database, not a live read, and it is a different class of tool.

3. BuiltWith#

BuiltWith is the best known technographics database. Its strength is breadth and history: detailed per-site profiles, a long record of what a domain has run over time, and the ability to build lists of sites by the technology they use. For market research, competitive teardowns and “find me every Shopify store in this niche” queries, it is a standard.

The free profile view is genuinely useful for a quick look at one domain. The serious capabilities, full technology lists, exports, large result sets, are paid, and the heavier tiers are not cheap. If your use case is building targeted lists at volume, it can be worth it, but treat the price as a real line item and check the current plans directly, because they are revised periodically.

4. WhatCMS#

WhatCMS is narrower and, for one specific question, very efficient. Paste a URL and it identifies the content management system, often with a version number. It is built around CMS identification rather than the full stack, which makes it a quick, focused confirmation tool when the CMS is all you need.

It offers a free single lookup and a paid API for anyone who needs to identify the CMS across many domains programmatically. If you are scripting CMS detection into a workflow, the API is the relevant piece; for one-off checks, the free lookup is fine. As always, the rate limits and pricing on the API are worth verifying on the WhatCMS site before building against them.

The manual fallback: view-source and headers#

5. Your browser’s own tools#

No tool list is complete without the method that needs no tool at all. Your browser already shows you most of what a detector reads: the page source, the response headers, the cookie names, the robots.txt and sitemap. It is free, always available, and immune to whatever a detector happens not to cover, though it will not scale to a thousand sites or match a maintained fingerprint library for obscure tools.

This guide is about choosing a tool, so it will not repeat the step-by-step here. If you want the manual reading walked through properly, the companion guide on how to detect the CMS a website uses covers exactly which signals to look for and what each one can and cannot tell you. For a single high-value prospect, that manual route is worth knowing, and it is the most honest about its limits: when the tells are not in the page, you simply do not get an answer.

The prospecting layer: from detection to outreach#

Here is where detection stops being trivia. Knowing one site’s stack is useful. Turning stack data, and the gaps in it, into a filtered, contactable, prioritized list is what actually drives outreach. These tools operate at that layer, and they are not detectors in the same sense as the ones above. They are where the signal gets used.

6. Apollo#

Apollo is a sales database and engagement platform, and technographics are one of its filters. Alongside firmographics like industry, headcount and location, you can narrow a prospect search by the technologies a company uses, then pull contact details and run sequences from the same place. For teams that want technology as one criterion inside a broader targeting and outreach workflow, it consolidates several steps.

The depth of the technographic data and the export and sequencing volume depend on the plan, and the useful tiers are paid. There is a free tier to evaluate the interface and run small tests; verify what the technology filter and the export limits actually include on your plan before you lean on it, since these change.

7. Clay#

Clay sits one layer out, as an enrichment and orchestration tool. It pulls data from many providers into a spreadsheet-style workflow, so you can take a raw list of domains, enrich each row with detected technologies, firmographics and contact data from whichever sources you connect, and shape the result into exactly the segmented list you want. It is less a detector than a way to combine detection with everything else you know about a prospect.

That flexibility comes with a learning curve and with credit-based pricing that scales with how much you enrich and which providers you call. It is powerful for building bespoke, multi-signal lists, and it is more than you need if you only want a quick stack read. Check current credit costs on Clay’s site before designing a large workflow around it.

8. Inflowave#

Inflowave is an Instagram-focused lead generation and outreach automation platform aimed at agencies. Its relevance to a stack-and-gaps workflow is specific rather than general: when a gap check flags local businesses that are weak on the web but active on Instagram, the follow-up can run where those businesses already pay attention. It is a fit for that case and not for every list, since it centers on Instagram outreach rather than broad technographic search or email sequencing.

As with the others, the meaningful capabilities sit on paid plans, and the right way to judge fit is to confirm the current features and pricing on the Inflowave site against the specific motion you are running.

9. A gap-first stack checker#

The tools above answer “what is present” well, and the database players answer “who runs what” well. The piece most of them treat as secondary is the absence: the missing CRM, the missing pixel, the missing chat widget, the missing booking tool. For prospecting, that absence is frequently the entire pitch, because each gap maps to a service an agency sells.

That is the lens Website Technology Checker is built around. It reads the same public fingerprints any detector does, then leads with what is missing and scores those gaps for how clearly they signal an opportunity. The web checker comes first, with a Chrome extension to follow, and both are free at launch. If a gap-first read is the part your current stack of tools does not give you, the waitlist is the place to start.

What stack to actually use#

You do not need all nine. Match the tool to the job:

• For a fast read on one site you are looking at, install Wappalyzer, and add WhatRuns as a free second opinion. Both are free for single-site lookups.
• For lists of sites by technology, or historical stack data, BuiltWith is the standard, with WhatCMS as a focused option when the CMS is all you need. Expect the serious data to be paid.
• For one high-value prospect, do not underrate reading view-source and headers yourself. It is free and it never lies about what it cannot see.
• To turn detection into outreach, the prospecting layer, Apollo for technographic search and sequencing, Clay for multi-source enrichment, and Inflowave where Instagram is the channel, is where stack data becomes a contactable list.
• To make the gaps the headline rather than a footnote, a gap-first checker fills the slot the general detectors leave open.

Detection is the easy half. The value is in what you do with it: reading the stack to qualify the lead, reading the gaps to know what to say, and only then reaching out. If you want the gap-first piece of that workflow the moment it ships, join the waitlist.