Website technology lookup tools let you discover exactly what software, frameworks, and services power any website. They are used by developers evaluating technology choices, marketers researching competitors, and sales teams qualifying leads. But with several tools on the market, which one should you use?
In this guide, we compare the top options across the dimensions that matter most: detection accuracy, number of technologies covered, API access, pricing, and the best use case for each tool.
What Do Technology Lookup Tools Actually Detect?
Most website technology detection tools analyze some combination of these data sources:
- HTTP response headers — Server software, frameworks, caching layers, security headers
- HTML source code — Meta generator tags, inline scripts, CSS class patterns, DOM structure
- JavaScript — Global variables, SDK URLs loaded via script tags
- Cookies — Session cookies, tracking cookies, analytics identifiers
- DNS records — TXT verification records, CNAME aliases, MX records that reveal email and hosting providers
- ads.txt — The advertising transparency file that lists SSPs and ad exchanges a publisher works with
The more data sources a tool analyzes, the more comprehensive its detection. A tool that only checks HTML will miss server-side technologies like CDNs, DNS-based services, and advertising relationships.
For Developers: API Access and Integration
If you need to integrate technology detection into your own application, API access is essential. WhatStack's REST API returns clean JSON with a simple GET request and includes a free tier of 500 requests per month. Wappalyzer also offers an API, though it starts at $250/month. BuiltWith has an API as well, but pricing is enterprise-level.
For developers building internal tools, CRM integrations, or automated lead qualification pipelines, the key factors are: response format (JSON is standard), rate limits, latency (real-time vs cached data), and the granularity of the response (does it include confidence scores? version numbers? category information?).
For Marketers: Competitive Intelligence
Marketers use technology lookup tools to understand competitor strategies. What analytics tool does a competitor use? What A/B testing platform? What advertising networks? This data helps shape your own marketing technology choices and reveals opportunities.
For this use case, the breadth of technology coverage matters most. A tool that detects analytics, ad tech, marketing automation, CRM integrations, and live chat platforms gives you the fullest picture. WhatStack and BuiltWith both offer broad coverage here, while WhatCMS focuses narrowly on CMS identification.
For Sales Teams: Lead Qualification
Sales teams use technology detection to qualify leads before outreach. If you sell a Shopify app, you want to know which prospects actually use Shopify. If you sell a WordPress migration service, you need to find companies running outdated WordPress versions.
The ideal tool for sales combines technology detection with the ability to process lists of domains in bulk. WhatStack supports bulk scanning via API, letting you scan up to 25 URLs in a single request. BuiltWith and SimilarTech offer pre-built lead lists segmented by technology, which is convenient but comes at a premium price.
Accuracy and Freshness
There is an important distinction between tools that scan websites in real time and those that serve cached data from periodic crawls. Real-time scanners (like WhatStack) hit the live website on every request, so you always get current results. Crawler-based tools (like BuiltWith and SimilarTech) may show data that is days or weeks old.
For one-off lookups, real-time scanning is more accurate. For historical trend analysis, cached data from regular crawls is more useful because it shows how a site's stack has changed over time.
Pricing Overview
Pricing varies dramatically across the market. Here is a quick summary:
- WhatStack: Free tier (500 req/mo), paid from EUR 19/mo. See pricing
- Wappalyzer: Free browser extension, API from $250/mo
- BuiltWith: From $295/mo (no free API tier)
- WhatCMS: Free tier, paid from $10/mo
- SimilarTech: Enterprise pricing (contact sales)
Which Tool Should You Use?
The right choice depends on your primary use case:
- Developer building an integration? WhatStack — free API, clean JSON, real-time results
- Marketer doing competitor research? WhatStack or Wappalyzer for broad tech detection at reasonable prices
- Sales team qualifying leads at scale? WhatStack's bulk API for automated qualification, or BuiltWith for pre-built lead lists if budget allows
- Just need to know the CMS? WhatCMS for a quick, focused answer
- Market research and trends? SimilarTech or W3Techs for macro-level adoption data
The best place to start is always with a free tool. Enter any URL in the WhatStack scanner and see the full technology profile for yourself.