Website Technology Lookup API: The Complete Developer Guide (2026)

Every website leaks clues about the technologies behind it. HTTP headers reveal the server. HTML meta tags expose the CMS. JavaScript globals betray the frontend framework. A website technology lookup API collects all these signals and returns a structured answer: here is exactly what this site is built with.

This guide covers how website technology detection works under the hood, when to build your own versus using an existing API, and how to integrate a website tech stack API into your applications with working code examples.

Why Developers Need Tech Stack Detection

Programmatic technology detection is not a novelty — it solves real business problems across multiple domains.

Lead generation and qualification

Sales teams targeting Shopify merchants, WordPress agencies, or React developers need to identify prospects at scale. A tech stack API lets you scan thousands of domains and filter by technology, turning a raw lead list into a qualified pipeline. If a company runs Magento, your WooCommerce migration service is relevant. If they use HubSpot, your Salesforce pitch is not.

Competitive analysis

Before choosing your own stack, it pays to know what the market leaders in your space are using. Are your competitors on Next.js or Nuxt? Do they use Cloudflare or AWS CloudFront? A website technology detection API answers these questions in milliseconds, not hours of manual research.

Security auditing

Exposed technology versions are attack vectors. If a site advertises that it runs jQuery 2.1.4 or PHP 5.6 in its headers, that is actionable intelligence for penetration testers and security auditors. Automated scanning via API lets you audit hundreds of subdomains in a single script.

Migration planning

When consolidating acquisitions or re-platforming a portfolio of sites, you first need an inventory. What CMS does each property use? What analytics tools are installed? A website tech stack API gives you that inventory programmatically — no manual inspection required.

How Website Technology Detection Works

A technology lookup API examines multiple layers of a website's public-facing footprint. Here are the primary detection signals:

• HTTP response headers: The X-Powered-By, Server, and X-Generator headers often directly identify the backend technology. A header like X-Powered-By: Express confirms Node.js. Server: nginx confirms the web server.
• HTML patterns: CMS platforms embed telltale markup. WordPress adds wp-content paths. Drupal includes Drupal.settings. Squarespace uses characteristic class names and div structures.
• JavaScript globals: Frameworks expose global objects. React sets __REACT_DEVTOOLS_GLOBAL_HOOK__. Vue exposes __VUE__. Angular uses ng-version attributes. These are reliable fingerprints.
• Meta tags: The <meta name="generator"> tag is used by WordPress, Ghost, Jekyll, Hugo, and many other platforms to self-identify.
• Cookie names: Specific cookie patterns indicate technologies. _shopify_s means Shopify. PHPSESSID means PHP. laravel_session means Laravel.
• Script and link URLs: CDN paths, file naming conventions, and resource URLs reveal frameworks, analytics tools, and third-party integrations.

A good detection engine combines all of these signals and assigns a confidence score — the more signals that match for a given technology, the higher the confidence.

Building Your Own vs. Using an API

You can build your own website technology detector. But should you?

Building a basic detector with 20-30 fingerprints is a fun weekend project. Maintaining a production-grade system with 100+ fingerprints, handling edge cases, keeping up with new frameworks, and managing infrastructure is a full-time job. For most teams, an API is the pragmatic choice.

Calling the StackPeek API: Code Examples

The StackPeek API requires a single query parameter — the URL you want to scan. No API key is needed for the free tier (100 scans/day).

curl

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

Node.js (fetch)

const url = "https://stackpeek.web.app/api/v1/detect?url=example.com";

const res = await fetch(url);
const data = await res.json();

console.log(data.technologies);
// [{ name: "Next.js", category: "framework", confidence: 0.95 }, ...]

Python (requests)

import requests

url = "https://stackpeek.web.app/api/v1/detect"
params = {"url": "example.com"}

response = requests.get(url, params=params)
data = response.json()

for tech in data["technologies"]:
    print(f"{tech['name']} ({tech['category']}) — {tech['confidence']}")

Reading the JSON Response

Every successful response follows the same structure:

{
  "url": "https://example.com",
  "technologies": [
    {
      "name": "React",
      "category": "framework",
      "confidence": 0.96
    },
    {
      "name": "Vercel",
      "category": "hosting",
      "confidence": 0.99
    },
    {
      "name": "Google Analytics",
      "category": "analytics",
      "confidence": 0.91
    }
  ],
  "scanTime": 287
}

Key fields:

• name — The detected technology (e.g., React, WordPress, Cloudflare)
• category — One of 15 categories: framework, cms, hosting, cdn, analytics, css, build_tool, payment, language, server, security, font, widget, cache, seo
• confidence — A float from 0 to 1. Values above 0.8 indicate strong detection. Multiple matching signals push confidence higher.
• scanTime — Detection time in milliseconds. Typical responses are under 500ms.

Real-World Use Cases with Code

Lead qualification bot

Scan a list of prospect domains and filter to those using a specific technology. This example finds all leads running Shopify:

import requests

leads = ["store-a.com", "store-b.com", "store-c.com"]
shopify_leads = []

for domain in leads:
    resp = requests.get(
        "https://stackpeek.web.app/api/v1/detect",
        params={"url": domain}
    )
    techs = [t["name"] for t in resp.json()["technologies"]]
    if "Shopify" in techs:
        shopify_leads.append(domain)

print(f"Found {len(shopify_leads)} Shopify stores")
print(shopify_leads)

Competitive monitoring script

Track when a competitor changes their tech stack. Run this on a weekly cron and diff the results:

import requests, json, os
from datetime import datetime

COMPETITOR = "competitor.com"
STATE_FILE = "competitor_stack.json"

resp = requests.get(
    "https://stackpeek.web.app/api/v1/detect",
    params={"url": COMPETITOR}
)
current = {t["name"] for t in resp.json()["technologies"]}

if os.path.exists(STATE_FILE):
    previous = set(json.load(open(STATE_FILE)))
    added = current - previous
    removed = previous - current
    if added or removed:
        print(f"[{datetime.now()}] Stack changed!")
        if added: print(f"  Added: {added}")
        if removed: print(f"  Removed: {removed}")

json.dump(list(current), open(STATE_FILE, "w"))

Pricing: StackPeek vs. Wappalyzer vs. BuiltWith

Website technology lookup APIs vary wildly in price. Here is a direct comparison for 2026:

StackPeek covers 120+ technologies across 15 categories. That is fewer than Wappalyzer's 1,500+ or BuiltWith's 90,000+ database — but it covers the technologies that matter for 90% of use cases (frameworks, CMS, hosting, CDN, analytics, payments) at 28x less cost.

For most developers building lead gen tools, competitive monitors, or internal dashboards, StackPeek's coverage is more than sufficient. You probably do not need to detect which WordPress theme variant or obscure jQuery plugin a site is running.

Getting Started

1. Test the free tier: Hit the API endpoint with curl or your browser. No signup needed.
2. Integrate into your app: Use the code examples above to add tech detection to your lead gen, monitoring, or research workflows.
3. Scale up: When you exceed 100 scans/day, upgrade to a paid plan starting at $9/month for 5,000 scans.

The API is a single GET request. If you can call a REST endpoint, you can detect website technology stacks. No SDKs to install, no authentication to configure on the free tier, no headless browsers to manage.