How to Find What Technology a Website Uses (5 Methods, 2026)

Every website leaves fingerprints. The frameworks it runs, the CDN that serves its assets, the analytics tools tracking visitors, the payment processor handling checkout — all of it is detectable if you know where to look. Whether you are scoping out a competitor, building a lead list, or auditing your own infrastructure, knowing how to find what technology a website uses is one of the most valuable skills in modern web development and digital marketing.

This guide covers five distinct methods, ranked from fully manual to fully automated. We will compare cost, speed, accuracy, and scalability so you can pick the right approach for your use case.

Why Knowing a Website's Tech Stack Matters

Before diving into the methods, it helps to understand why tech stack detection is worth doing in the first place. The answer usually falls into one of three buckets.

Competitive analysis

If you are choosing between Next.js and Nuxt, or between Shopify and WooCommerce, knowing what your direct competitors have shipped — and how well it performs — gives you real-world data instead of guesswork. You can see which CDN they trust, whether they have migrated off legacy stacks, and what analytics tools they rely on. This is especially useful when pitching architecture decisions to non-technical stakeholders: "Our three biggest competitors all use Cloudflare and Next.js" is a stronger argument than a Medium article.

Lead generation and sales intelligence

Sales teams at SaaS companies routinely use tech stack data to qualify leads. If you sell a Heroku alternative, you want a list of companies currently running on Heroku. If you sell a Segment competitor, you want to know who has Segment's JavaScript snippet on their homepage. Tech stack detection turns the entire internet into a searchable prospect database. Companies like BuiltWith have built eight-figure businesses on exactly this premise.

Security auditing

Every technology a website exposes is a potential attack surface. Outdated jQuery versions, known-vulnerable WordPress plugins, and misconfigured server headers are all discoverable through stack detection. Penetration testers and security researchers use these techniques in the reconnaissance phase of every engagement. Even if you are just auditing your own site, you want to know exactly what you are exposing to the public internet.

Method 1: Browser DevTools (Free, Manual)

The simplest way to find what technology a website uses is to open your browser's developer tools and start reading. No extensions, no API keys, no cost. Just you and the source code.

View Page Source

Right-click any page and select View Page Source (or press Ctrl+U / Cmd+Option+U). Look for telltale signs in the HTML:

• __next or __NEXT_DATA__ — Next.js
• wp-content or wp-includes — WordPress
• cdn.shopify.com — Shopify
• gtag or google-analytics.com — Google Analytics
• fbevents.js — Meta Pixel
• stripe.com/v3 — Stripe

Network tab

Open DevTools (F12), go to the Network tab, and reload the page. Filter by JS, CSS, or Font to see which third-party resources are loaded. CDN hostnames like cdn.jsdelivr.net, unpkg.com, or cdnjs.cloudflare.com reveal specific libraries. Response headers often expose the server (Server: nginx) or platform (X-Powered-By: Express).

Console

Some frameworks expose themselves on the global scope. Type window.__NUXT__ to check for Nuxt.js, or window.React to confirm React is loaded. Angular apps typically have ng-version attributes on the root element.

Pros: Completely free. No tools to install. Works on any website.
Cons: Extremely slow. Requires expertise to interpret what you see. Does not scale at all — you can realistically check maybe 5-10 sites per hour this way. Easy to miss things hidden behind lazy loading or server-side rendering.

Method 2: Browser Extensions (Free, Semi-Automated)

Browser extensions like Wappalyzer and BuiltWith automate what you would otherwise do manually in DevTools. Install the extension, visit any website, and click the icon to see a categorized list of detected technologies.

Wappalyzer is the most popular option with over 6 million users. It detects 1,500+ technologies across categories like CMS, frameworks, analytics, payment processors, and hosting providers. The extension is free and works well for one-off lookups.

BuiltWith's free extension offers similar detection and also links to their paid platform for deeper analysis, including historical data and market share statistics.

Pros: Free for browser-based use. Fast results (instant after page load). Good accuracy for common technologies. No technical expertise required.
Cons: No API access on the free tier. Cannot automate or batch process URLs. Wappalyzer's API starts at $250/month. Limited to one site at a time. Extensions can slow down browsing. Privacy concerns with some extensions sending browsing data to their servers.

Method 3: Online Lookup Tools (Expensive)

If you need more than a browser extension but less than a full API integration, several online tools let you type in a URL and get back a tech stack report.

BuiltWith.com

The gold standard for technology profiling, especially in enterprise sales. BuiltWith maintains a database of 90,000+ technologies and tracks historical changes. You can search by technology to find all websites using a specific tool, which makes it powerful for lead generation. However, pricing starts at $295/month for their basic plan, and the free tier is severely limited.

W3Techs

W3Techs provides technology surveys and market share data for the top 10 million websites. It is useful for macro-level trends (e.g., "What percentage of sites use React?") but less useful for checking individual URLs on demand.

SimilarTech

SimilarTech focuses on technographic lead generation and competitive intelligence. Pricing is enterprise-only (contact sales), which puts it out of reach for most individual developers and small teams.

Pros: Deep databases. Historical data. Lead generation features. Market share reports.
Cons: Expensive ($295-500+/month). Slow response times (3-8 seconds per lookup). Often overkill if you just need to know what framework a site uses. Free tiers are too limited for real work.

Method 4: StackPeek API (Fast, Cheap, Programmatic)

This is where things get interesting for developers. StackPeek provides a REST API that detects 120+ technologies in under 500 milliseconds, starting at $9/month with a free tier of 100 scans per day.

Unlike Wappalyzer or BuiltWith, StackPeek does not use a headless browser. Detection is done through HTTP header analysis, HTML pattern matching, script fingerprinting, and meta tag parsing. This makes it significantly faster and more predictable than browser-based detection tools.

What StackPeek detects

StackPeek identifies technologies across 15 categories:

• Frameworks: React, Next.js, Vue, Nuxt, Angular, Svelte, Gatsby, Remix
• CMS: WordPress, Drupal, Ghost, Webflow, Squarespace, Wix
• Hosting & CDN: Vercel, Netlify, Cloudflare, AWS, Firebase, Heroku
• Analytics: Google Analytics, Plausible, Fathom, Hotjar, Mixpanel
• E-commerce: Shopify, WooCommerce, BigCommerce, Stripe, PayPal
• CSS: Tailwind CSS, Bootstrap, Bulma, Material UI
• Build tools: Webpack, Vite, Turbopack, esbuild
• And more: authentication, email, chat widgets, A/B testing, tag managers

For the vast majority of use cases — competitive analysis, lead qualification, security audits, portfolio research — 120+ technologies is more than enough. You rarely need to identify the exact WordPress theme variant or a niche jQuery plugin.

Code example: cURL

curl "https://stackpeek.web.app/api/v1/detect?url=https://linear.app"

Response (342ms):

{
  "url": "https://linear.app",
  "technologies": [
    { "name": "React", "category": "framework", "confidence": 0.97 },
    { "name": "Next.js", "category": "framework", "confidence": 0.94 },
    { "name": "Cloudflare", "category": "cdn", "confidence": 0.99 },
    { "name": "Stripe", "category": "payment", "confidence": 0.91 },
    { "name": "Segment", "category": "analytics", "confidence": 0.88 }
  ],
  "scanTime": 342
}

Code example: JavaScript (Node.js / browser)

async function detectStack(url) {
  const endpoint = `https://stackpeek.web.app/api/v1/detect?url=${encodeURIComponent(url)}`;
  const response = await fetch(endpoint);
  const data = await response.json();

  console.log(`Technologies found for ${data.url}:`);
  data.technologies.forEach(tech => {
    console.log(`  ${tech.name} (${tech.category}) — ${Math.round(tech.confidence * 100)}% confidence`);
  });
  console.log(`Scan completed in ${data.scanTime}ms`);

  return data;
}

// Scan a single URL
detectStack("https://stripe.com");

// Batch scan multiple URLs
const urls = ["https://vercel.com", "https://linear.app", "https://notion.so"];
const results = await Promise.all(urls.map(detectStack));

That batch scan takes roughly 1 second total for 3 URLs running in parallel. Try doing that with a browser extension.

Pros: Fast (<500ms). Cheap ($9/month or free for 100/day). REST API works from any language. Confidence scores for each detection. No headless browser overhead. Batch-friendly.
Cons: Smaller detection database (120+) compared to Wappalyzer (1,500+) or BuiltWith (90,000+). No historical data. Newer product with a smaller community.

Method 5: Build Your Own Detector (DIY)

If you are a developer and need full control, you can write your own tech stack detection logic. The basic approach involves fetching a URL, then checking HTTP headers, HTML content, and loaded scripts against a set of known patterns.

Here is a simplified version of what that looks like:

import requests

def detect_tech(url):
    r = requests.get(url, timeout=10)
    html = r.text.lower()
    headers = {k.lower(): v.lower() for k, v in r.headers.items()}
    found = []

    # Check headers
    if 'x-powered-by' in headers:
        found.append(('Server', headers['x-powered-by']))
    if 'cloudflare' in headers.get('server', ''):
        found.append(('CDN', 'Cloudflare'))

    # Check HTML patterns
    patterns = {
        '__next': 'Next.js',
        'wp-content': 'WordPress',
        'cdn.shopify.com': 'Shopify',
        'gtag': 'Google Analytics',
        'tailwindcss': 'Tailwind CSS',
    }
    for pattern, name in patterns.items():
        if pattern in html:
            found.append(('Tech', name))

    return found

This works for a handful of technologies. The problem is maintenance. New framework versions change their fingerprints. CDNs rotate hostnames. CMS platforms update their markup. What starts as a simple script quickly becomes a maintenance nightmare that someone on your team has to keep updating.

Wappalyzer's open-source fingerprint database has over 4,000 detection rules maintained by hundreds of contributors. Replicating even a fraction of that is a multi-month project. And keeping it current is a never-ending job.

Pros: Full control over detection logic. No external dependencies. Free (aside from your time).
Cons: Enormous maintenance burden. Limited accuracy without a large fingerprint database. You are reinventing the wheel. Time spent maintaining detection rules is time not spent on your actual product.

Comparison: All 5 Methods Side by Side

Which Method Should You Use?

The right answer depends on your situation:

You need to check one site right now: Open DevTools or install the Wappalyzer extension. It takes 30 seconds and costs nothing.

You need to check 10-50 sites for a research project: The Wappalyzer or BuiltWith browser extension will get the job done without spending a dime.

You are building a product that needs tech stack data: Use StackPeek's API. The free tier (100 scans/day) is enough for prototyping and MVPs. The $9/month plan (5,000 scans) covers most production use cases. You get structured JSON responses with confidence scores, which means clean data you can pipe directly into your application.

You are an enterprise sales team building lead lists at scale: BuiltWith or SimilarTech might be worth the premium if you need historical data, market share reports, and 90,000+ technology coverage.

You want full control and have engineering time to spare: Build your own detector. Just know that maintaining the fingerprint database is a serious, ongoing commitment.

Getting Started with StackPeek

If you want to start detecting tech stacks programmatically without the enterprise price tag, here is the fastest path:

1. Try it free: Hit the API endpoint with any URL. No API key required for the free tier.
2. Scan up to 100 sites per day at no cost. That is enough for testing, prototyping, and small-scale research.
3. Upgrade to the Starter plan ($9/month) when you need more than 100 scans per day or want higher rate limits.
4. Integrate into your workflow: StackPeek returns clean JSON with technology names, categories, and confidence scores. Pipe it into your CRM, your lead scoring model, your competitive dashboard, or wherever you need the data.

Every response includes a scanTime field in milliseconds so you can monitor performance. No headless browser means no cold starts, no timeouts, and no flaky results.

Related reading: Best Wappalyzer Alternative API in 2026 · Detect Website Frameworks Programmatically · Tech Stack API for Startup Lead Gen