Website Technology Checker: 9 Best Free Tools Compared [2026]

Quick answer: The fastest free way to see what technology a website uses is a web-based checker — no signup, no extension. Stackcrawler gives free no-signup web lookups; WhatRuns is the best free browser extension; BuiltWith has the deepest database but hides most results behind a $295/mo paywall; and Wappalyzer caps its free tier at 50 lookups a month. Full comparison, free-tier limits, and manual detection methods below.

You're about to hop on a sales call. You pull up the prospect's website and wonder: What CMS are they using? Do they have a chatbot? What analytics platform? Are they running HubSpot or Salesforce?

Or maybe you're a developer scoping a competitor's site, a marketer evaluating a potential partner, or a founder doing due diligence.

Whatever the reason, knowing what technology a website uses is incredibly valuable — and there are free tools that can tell you in seconds.

We compared 9 of the most popular website technology checker tools in 2026 on detection depth, speed, verified pricing, and actual free-tier usability. Here's what we found.

Why Check a Website's Technology Stack?

Before diving into tools, here's why this matters:

• Sales prospecting: If you sell a Shopify app and a prospect runs WooCommerce, you're wasting your time. Tech stack data lets you qualify leads instantly.
• Competitive intelligence: See what tools your competitors use for analytics, A/B testing, live chat, and marketing automation.
• Development scoping: Evaluate what frameworks, CDNs, and hosting providers a site relies on before building an integration.
• M&A due diligence: Understand technical debt and infrastructure before acquiring a company.
• Partnership evaluation: Check if a potential partner uses compatible technology before proposing an integration.

According to a 2025 Gartner report, the average mid-market company uses 120+ SaaS tools. That's a lot of technology surface area to analyze — and manual inspection won't cut it.

How Website Technology Checkers Work

Most tech stack detection tools use a combination of these methods:

1. HTTP header analysis — Server headers reveal web servers (Nginx, Apache), frameworks, and caching layers.
2. JavaScript library detection — Scanning the DOM for known JavaScript frameworks, analytics scripts, and tracking pixels.
3. DNS and SSL analysis — DNS records and SSL certificates can reveal hosting providers and CDN usage.
4. HTML meta tag scanning — CMS platforms often leave fingerprints in meta tags, generator tags, and structured data.
5. Cookie analysis — Different platforms set distinctive cookies that can be identified.
6. Pattern matching — Comparing page source code against databases of thousands of known technology signatures.

The best tools combine multiple methods to maximize detection accuracy.

The 9 Best Free Website Technology Checker Tools

1. BuiltWith

Website: builtwith.com

What it does: One of the original technology profiling tools. Enter a URL and get a detailed breakdown organized by category (analytics, frameworks, CDN, hosting, CMS, etc.).

Pricing:

• Free: Individual URL lookups with basic results
• Basic: $295/month (full technology lists, lead generation features)
• Pro: $495/month (extended historical data)
• Enterprise: $995/month (API access, bulk lookups)

Pros:

• Massive technology database (tracks 100,000+ technologies)
• Historical data showing when technologies were added or removed
• Market share data for each technology category
• Lead lists filtered by technology (paid feature)

Cons:

• Free tier shows limited results — many technologies are hidden behind the paywall
• Interface feels dated compared to newer tools
• Expensive if you need full data access
• Can be slow on complex sites

Best for: Enterprise teams with budget for deep technographic data and lead list building.

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2. Wappalyzer

Website: wappalyzer.com

What it does: Browser extension and web-based tool that identifies technologies on websites. Originally open-source, now a commercial product owned by Dun & Bradstreet.

Pricing (verified September 2026):

• Free: Browser extension with basic detection (50 lookups/month)
• Pro: $250/month (1 user, 2 lead-list technologies, 20,000 API credits)
• Business: $450/month (5 users, unlimited lead-list technologies, CRM integration)
• Enterprise: from $850/month

Wappalyzer has moved sharply upmarket — the old $99 Starter tier is gone, and the cheapest paid plan now costs $250/month. For occasional lookups, the free extension's 50/month cap is the practical limit.

Pros:

• Browser extension works passively as you browse — see tech stacks without leaving the page
• Well-organized categories (67+ technology categories)
• API available for programmatic access
• Company and contact data bundled in paid plans

Cons:

• Free tier is very limited (50 lookups/month)
• Was open-source, now fully commercial — some community resentment
• Browser extension can slow page loading
• Accuracy has declined according to some users after the acquisition

Best for: Users who want passive tech detection while browsing and are willing to pay for API access.

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3. WhatRuns

Website: whatruns.com

What it does: Browser extension that shows the technologies used by any website you visit. Focuses on simplicity.

Pricing: Free (with optional paid plans for teams)

Pros:

• Genuinely free browser extension
• Simple, clean interface
• Detects WordPress themes and plugins specifically
• Works on any page you visit

Cons:

• Chrome extension only — no web-based lookup
• Detection accuracy is lower than BuiltWith or Wappalyzer for less common technologies
• Limited to what can be detected client-side
• No API or bulk scanning capabilities

Best for: Casual users who want a free browser extension for quick checks.

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4. Stackcrawler

Website: stackcrawler.com

What it does: Web-based technology checker with a focus on CMS and e-commerce platform detection (particularly strong at identifying Shopify stores).

Pricing: Free for individual lookups

Pros:

• Good at e-commerce platform detection (Shopify, WooCommerce, Magento)
• Clean, modern interface
• No signup required
• Includes some hosting and CDN detection

Cons:

• Narrower technology coverage than BuiltWith or Wappalyzer
• E-commerce focus means it may miss SaaS tools, marketing tech, and analytics
• No bulk scanning
• Limited to major technology categories

Best for: E-commerce professionals who primarily need CMS and platform detection.

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5. W3Techs

Website: w3techs.com/sites

What it does: Academic-grade technology survey tool. Enter a URL to check specific technology categories, or browse their extensive market share reports.

Pricing: Free for site lookups; premium reports available

Pros:

• Extremely accurate for server-side technologies (web servers, programming languages, CMS)
• Trusted by researchers — their methodology is transparent and well-documented
• Market share data updated daily
• No account required

Cons:

• Doesn't detect client-side technologies well (JavaScript frameworks, analytics, marketing tools)
• Interface is functional but not pretty
• Focused on top-level technologies, not granular MarTech detection
• No API for programmatic access

Best for: Developers and researchers who need reliable server-side technology data.

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6. Hexomatic Tech Stack Analyzer

Website: hexomatic.com/tools/tech-stack-analyzer

What it does: Free tool that detects technologies used on any website, with results organized by category.

Pricing: Free tool (part of Hexomatic's automation platform; paid plans start at $20/month)

Pros:

• Detects 1,000+ technologies
• Free to use without signup
• Can be combined with Hexomatic's automation workflows for bulk scanning
• Decent accuracy for common technologies

Cons:

• Free tool shows basic results; advanced features require a Hexomatic subscription
• Slower than dedicated tech stack tools
• Part of a broader platform — not a focused tech detection product
• Detection database isn't as comprehensive as BuiltWith

Best for: Users already on Hexomatic's platform who want to add tech detection to their automation workflows.

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7. Seomator Website Technology Checker

Website: seomator.com/website-technology-checker

What it does: Free technology lookup as part of Seomator's SEO audit platform.

Pricing: Free for individual lookups

Pros:

• No signup required
• Combines tech stack data with SEO audit information
• Decent at detecting CMS, JavaScript libraries, and analytics tools

Cons:

• Limited technology database
• Primarily an SEO tool — tech detection is a secondary feature
• Results can be incomplete for non-web-standard technologies
• No bulk or API access

Best for: SEO professionals who want tech stack data as part of a broader site audit.

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8. WhatCMS

Website: whatcms.org

What it does: Focused tool for detecting Content Management Systems. Also identifies hosting providers and some web technologies.

Pricing: Free for individual lookups; API plans from $10/month

Pros:

• Best-in-class CMS detection (identifies 800+ CMS platforms)
• Also detects WordPress themes and plugins
• API available at reasonable prices
• Fast and accurate for its focus area

Cons:

• CMS-focused — doesn't detect most MarTech, analytics, or development frameworks
• Not useful if you need a full technology profile
• Limited free API calls (10/day)

Best for: Agencies and developers who primarily need to identify CMS platforms.

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9. Ful.io

Website: ful.io

What it does: Technology detection with a Chrome extension and web-based lookup. Includes contact information discovery.

Pricing: Free tier available; paid plans for team features

Pros:

• Combines tech detection with contact info discovery
• Chrome extension for passive detection
• Includes e-commerce platform identification

Cons:

• Newer tool with smaller technology database
• Free tier has usage limits
• Accuracy varies depending on the technology category
• Less established reputation

Best for: Users who want tech detection and contact data in one tool.

Quick Comparison Table

Tool	Free Tier	Technologies Detected	Signup Required	Bulk Scan	API
BuiltWith	✅ Limited results	100,000+	No	Paid	Paid ($295+/mo)
Wappalyzer	✅ 50/month	3,000+	Yes	Paid	Paid ($250+/mo)
WhatRuns	✅ Free extension	1,000+	No	No	No
Stackcrawler	✅ Unlimited	500+	No	No	No
W3Techs	✅ Free	Server-side focused	No	No	No
Hexomatic	✅ Free tool	1,000+	No	Paid	Paid
Seomator	✅ Free	300+	No	No	No
WhatCMS	✅ Limited	CMS-focused (800+)	No	API only	$10/mo
Ful.io	✅ Limited	1,000+	Yes	No	No

How to Check What Technology a Website Uses — Without Any Tool

Sometimes you can't (or don't want to) paste a URL into a third-party checker. Every technology checker on this list is automating the same handful of inspection techniques, and you can do them manually in your browser in under two minutes:

1. View the page source (Ctrl+U / Cmd+Option+U). Search for wp-content (WordPress), cdn.shopify.com (Shopify), _next/static (Next.js), wix.com (Wix), or squarespace — the CMS almost always fingerprints itself. A <meta name="generator"> tag frequently names the platform and version outright.
2. Open DevTools → Network tab and reload. The request list shows every third-party script loading: js.hs-scripts.com means HubSpot, www.googletagmanager.com means Google Tag Manager, cdn.segment.com means Segment, js.intercomcdn.com means Intercom.
3. Check response headers (Network tab → click the main document → Headers). Server, X-Powered-By, and Via headers reveal the web server, framework, and CDN — cf-ray means Cloudflare, x-vercel-id means Vercel, x-served-by: cache-* usually means Fastly.
4. Inspect cookies (DevTools → Application → Cookies). _shopify_* cookies mean Shopify, hubspotutk means HubSpot, _ga means Google Analytics, intercom-* means Intercom.
5. Probe common paths. /wp-json/ returning JSON confirms WordPress; /robots.txt and /sitemap.xml often reference platform-specific paths.

This is exactly what the automated checkers do at scale — pattern-matching against thousands of known signatures. Manual inspection is free and educational; the tools are just faster and catch technologies you wouldn't think to look for.

The Best Free BuiltWith Alternatives in 2026

BuiltWith is the household name in technology profiling, but its free tier hides most results and full access starts at $295/month (billed annually — monthly costs more). If that's the paywall you just hit, here's the short version of your free options:

If you need...	Free BuiltWith alternative
Unlimited one-off URL lookups, no signup	Stackcrawler
Passive detection while browsing	WhatRuns (free Chrome extension)
Occasional lookups with category depth	Wappalyzer free tier (50/month)
CMS identification specifically	WhatCMS
Server-side tech and market-share research	W3Techs

The honest trade-off: nothing free matches BuiltWith's 100,000+ technology database or its historical "when did they add Marketo" data. But for the core question — what is this website built with? — the free tools above answer it in seconds without a $3,540/year commitment. If your real goal is building lead lists filtered by technology, see our guide to the best B2B lead generation tools — several include technographic filters at a fraction of BuiltWith's price.

How to Use Tech Stack Data for Sales Prospecting

Knowing what tools a website uses is only valuable if you act on it. Here's the playbook:

1. Qualify Leads by Technology Fit

If you sell a Salesforce integration, check if prospects actually use Salesforce before reaching out. This alone can double your reply rates by eliminating bad-fit prospects. Tech fit is one of the strongest buying signals in signal-based selling.

2. Personalize Your Outreach

"I noticed you're running HubSpot with a WordPress site" is a dramatically better opening line than "Hi, I'd like to tell you about our product." Tech stack data makes personalization effortless.

3. Identify Competitive Displacement Opportunities

If a prospect uses a competitor's product, you know exactly what to position against. "I see you're on Marketo — here's how teams like yours have saved 40% by switching" hits harder than a generic pitch.

4. Build Targeted Account Lists

Filter your total addressable market by technology to create hyper-focused lists. Companies using Shopify + Klaviyo + Google Analytics represent a very different buyer than those using Magento + Salesforce + Adobe Analytics. Pair technographic filters with a lookalike company finder to expand from your best customers, then fill in contacts with free lead generation tools or data enrichment tools.

5. Trigger Event-Based Outreach

If you can detect when a company adds or removes a technology, that's a buying signal. Company just added Drift? They're investing in conversational marketing and might be open to related tools. The same logic applies in reverse: website visitor identification tools tell you which companies are researching you, so you can check their stack before the first touch.

When to Use Which Tool

• Quick individual lookups (no signup): Stackcrawler — paste a URL, get results instantly
• Passive browsing detection: WhatRuns (free Chrome extension)
• Enterprise technographic data: BuiltWith (if you have the budget)
• Programmatic/API access: Wappalyzer or WhatCMS
• CMS-specific detection: WhatCMS
• E-commerce platform focus: Stackcrawler
• Server-side technology research: W3Techs

The Bottom Line

For most users — especially sales reps, marketers, and founders — the best website technology checker is the one that gives you accurate results without friction. You shouldn't need to create an account, install an extension, or pay $295/month just to see what CMS a website uses.

For one-off lookups, Stackcrawler answers the question in seconds with no signup. For passive detection while you browse, install WhatRuns. And if you only need the CMS, WhatCMS nails it.

If the reason you're checking tech stacks is sales prospecting, the tech data is just step one — the real work is turning qualified accounts into meetings. That's what MarketBetter does: it combines signals like technology fit and website visitor activity into a daily playbook that tells your SDRs exactly who to contact and what to say.

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Looking for more free tools? Check out our AI Lead Generator to find buyer contacts at any company, or use the Lookalike Company Finder to discover companies similar to your best customers.