Website Technology Reverse Search & Change History (16M sites, monthly)

What does it do?

Answers the questions a live "what does this site run?" tool cannot:

• reverse: which websites use a technology or category? "Every site in the top 100k that runs Klaviyo", "all Shopify stores in the top 1M", "the e-commerce platforms of the top 10k". Filtered by popularity, one row per website.
• changes: who switched? "Sites that added Shopify since June", "sites that removed Magento", "WordPress 6.5 → 6.6". Month-to-month changes for 16 million websites, with a flag for whether desktop and mobile agree.

And, for completeness:

• lookup: the full stack of the domains you list (up to 10,000 per run), from the same monthly snapshot.
• adoption: how many sites use a technology, by popularity bucket and month ("share of Next.js in the top 10k").

The data is the HTTP Archive monthly crawl: every website in the Chrome UX Report (16.1 million origins, 12.5 million registrable domains) loaded in a real browser, on desktop and mobile, with technologies detected by the HTTP Archive's open-source fork of Wappalyzer (3,600+ technologies in 100+ categories, with the version when the page exposes it). Use it as an API, schedule it, or call it from an AI agent through MCP (see "Use with AI agents (MCP)").

Data last updated: 27 October 2026 (latest crawl: October 2026; RUN_SUMMARY.latest_crawl and data_build_date on every run). Refreshed monthly, after the HTTP Archive crawl is final.

Try before you pay: the adoption figures, the technology catalog and a slice of the month-to-month changes (top 10k, latest month) are a free dataset on Hugging Face: https://huggingface.co/datasets/pracadata/website-technologies. Check the schema and the quality there, then come back for the reverse search, the full change history and the API.

How is this different from a lookup tool?

	Tools that detect a site live	This Actor
Question it answers	What does this URL run right now?	Which sites run X? What changed? What did this domain run in the last crawl?
Coverage	Any URL you give	The 16.1 million popular origins of the Chrome UX Report. Small and brand-new sites are not in it
Freshness	Today	Monthly: data is up to about six weeks old
History	Usually none	Change feed since the first crawl of this build, and 3 crawls of lookup
Reliability	Timeouts and blocked requests happen	Served from a prepared snapshot: no live crawling, no timeouts, no proxies, same answer every time
Detection	Mostly the HTML of one request	Real browser, so JavaScript-only technologies (tag managers, SPA frameworks, analytics) are found
Contact data	Some add e-mails and phones	None: websites and software only

If you need to check a site that is not in the 16.1M, or must see today's stack, use a live tool. If you need lists ("who uses X"), movements ("who switched to X") or trends, this is the data.

What data can it return?

Mode	One row is	Main fields
reverse	one website using the technology or category	origin, reg_domain, rank_bucket, crawl_month, technology, categories, versions, detected_desktop, detected_mobile, source
changes	one change of one website between two crawls	month_from, month_to, origin, reg_domain, rank_bucket, technology, change_type, old_versions, new_versions, confidence, source
lookup	one domain you asked for	input, reg_domain, origin_urls, n_origins, crawl_month, rank_bucket, technologies (list of {technology, categories, versions, detected_desktop, detected_mobile}), n_technologies, source
adoption	one technology × category × month	crawl_month, technology, category, rank_bucket, origins, origins_in_bucket, share_of_origins, source

rank_bucket is the Chrome UX Report popularity bucket: 1000 means the top 1k websites, then 5k, 10k, 50k, 100k, 500k, 1M, 5M, 10M and 50M. source carries the attribution on every row: Derived from the HTTP Archive (October 2026 crawl).

How to use it

1. Choose a mode.
2. reverse: type technology names (Shopify, Klaviyo, Google Tag Manager) or categories (Ecommerce, CMS). changes: technologies and/or domains, plus since_month. lookup: paste domains or URLs. adoption: technologies or categories.
3. Optional: rank_max (top N), min_confidence (both_clients = desktop and mobile agree), change_types, month.
4. Set Maximum results (default 1,000). Results are charged one by one, so this is your cost cap.
5. Run it and download JSON, CSV or Excel, or read the dataset through the API.

Input examples

Websites in the top 100k that use Klaviyo, latest crawl:

{ "mode": "reverse", "technologies": ["Klaviyo"], "rank_max": 100000, "max_rows": 5000 }

E-commerce platforms of the top 10k, both clients agreeing:

{ "mode": "reverse", "categories": ["Ecommerce"], "rank_max": 10000, "min_confidence": "both_clients", "max_rows": 10000 }

Who added Shopify since the oldest month, in the top 1M (changes both desktop and mobile agree on, the default):

{ "mode": "changes", "technologies": ["Shopify"], "since_month": "2026-08", "rank_max": 1000000, "change_types": ["added"], "max_rows": 5000 }

Who removed Shopify (not detected in the later crawl) in the same period:

{ "mode": "changes", "technologies": ["Shopify"], "since_month": "2026-08", "rank_max": 1000000, "change_types": ["removed"], "max_rows": 5000 }

Monthly share of Next.js in the top 10k:

{ "mode": "adoption", "technologies": ["Next.js"], "rank_max": 10000 }

Full stack of three domains (the default input, a fast and cheap test):

{ "mode": "lookup", "domains": ["shopify.com", "wordpress.org", "nytimes.com"] }

Output example (lookup)

{ "input": "www.example.com", "reg_domain": "example.com", "origin_urls": ["https://www.example.com/"], "n_origins": 1, "crawl_month": "2026-10", "rank_bucket": 100000,
  "technologies": [
    { "technology": "WordPress", "categories": ["CMS", "Blogs"], "versions": ["6.6.2"], "detected_desktop": true, "detected_mobile": true },
    { "technology": "Cloudflare", "categories": ["CDN"], "versions": [], "detected_desktop": true, "detected_mobile": true }
  ],
  "n_technologies": 2, "source": "Derived from the HTTP Archive (October 2026 crawl)" }

Read this before you trust a change

A change is a difference between two monthly crawls, and detections flicker (A/B tests, consent banners, lazy loading, a script that loads only sometimes). We measured how often a change reverses in the following month, over four consecutive month triples:

Changes	Reverse the next month
Desktop and mobile agree (both_clients)	4.3% overall; 9% of added and 12% of removed
Only one client saw it (single_client)	15.6% overall; 26% of added and 27% of removed

So changes returns both_clients by default (set min_confidence to any to include single-client changes; version_changed is reliable even single-client, 3.7%). removed means "not detected in this crawl", not "the site uninstalled it"; it is a strong signal for sales triggers, not a fact. The noise is higher among the most popular sites (many conditional scripts and bot-management layers). A website that is missing from a month's crawl never appears as removed: such sites are the separate entered_crawl / left_crawl change types. Half of all changes are version changes (Facebook Pixel, WordPress and a handful of other technologies produce almost half of them): filter by change_types and technologies.

Use with AI agents (MCP)

The Apify MCP server lets an AI agent find this Actor, read its input schema and call it as a tool (call-actor; the run's maxTotalChargeUsd goes in callOptions) and read the rows (get-dataset-items).

https://mcp.apify.com?tools=pracadata/website-tech-stack

• Claude (Desktop or web): Settings → Connectors → Add custom connector, paste the URL above, sign in to Apify.
• Cursor, VS Code and other mcpServers clients: { "mcpServers": { "apify": { "url": "https://mcp.apify.com?tools=pracadata/website-tech-stack" } } }. Without a browser, add "headers": { "Authorization": "Bearer <APIFY_TOKEN>" }.

What an agent should know. "Which sites use X?" → reverse with rank_max and a small max_rows. "Did X switch platforms?" → changes with domains (leave the three pre-filled example domains out, or replace them). "What does site X run?" → lookup. "How popular is X?" → adoption (small and cheap). Always set max_rows and a maximum charge per run; read RUN_SUMMARY.latest_crawl for freshness and RUN_SUMMARY.not_found for domains outside the snapshot.

Question	Input	Rows	Cost (at the prices below)
"Which top-100k sites use Klaviyo?"	reverse; Klaviyo, rank_max 100000	about 1,000	US$ 0.005 per site
"Which top-1M stores added Shopify since August?"	changes; Shopify, added, since_month 2026-08	depends	US$ 0.004 per change
"What tech stack does example.com use?"	lookup; domains [example.com]	1	US$ 0.0015
"How has Next.js adoption moved in the top 10k?"	adoption; Next.js, rank_max 10000	about 3	US$ 0.002 per row

Pricing

This Actor uses pay per event. The Pricing tab is authoritative; at the time of writing:

Event	What you are charged for	Price
reverse-lookup-row	each website returned by reverse	US$ 0.005
change-row	each change returned by changes	US$ 0.004
domain-lookup	each domain found by lookup	US$ 0.0015
adoption-row	each row returned by adoption	US$ 0.002

Domains not in the snapshot are free. Results are charged before they are delivered, in batches, and the Actor stops when your maximum charge per run is reached: you never get a row you were not charged for, and you are never charged for a row you did not get (RUN_SUMMARY.charged, stopped_by_spending_limit). There is no start fee.

Coverage and limitations

• Popular websites only. The list is the Chrome UX Report: 16.1 million origins with enough Chrome traffic. Small and brand-new websites are not in it. In lookup, a domain that is not in the crawl, or has no technology detected, is free and listed in RUN_SUMMARY.not_found.
• Home page only. Technologies used only on inner pages (checkout, blog, login) can be missed.
• About 3,600 technologies, far fewer than commercial databases. No detection does not prove that a site does not use a technology.
• Monthly, with lag. The crawl starts on the second Tuesday of the month and takes 1 to 2 weeks; the snapshot is updated after it is final. lookup keeps the 3 latest crawls, reverse the latest, changes and adoption the history since August 2026.
• reverse above the top 1M and lookup read from a private store, so the first row takes a couple of seconds. reverse inside the top 1M is served from the Actor itself. Above the top 1M a run reads at most 25 technologies (a whole category is fine at rank_max 1,000,000 or lower).
• Shared platforms. name.blogspot.com and name.github.io belong to their platform's registrable domain (blogspot.com, github.io). Use reverse/changes rows, which carry the full origin, to tell them apart.
• Detections flicker between months (see above). Versions are best effort, taken from what the page exposes; some are wrong.
• Crawled from the US. Websites that show different content by country may differ.

Privacy

The data describes websites and the software they run. Each row has a website's root URL, registrable domain, popularity bucket and detected technologies; no page content, no inner URLs, no cookies, no WHOIS, no e-mails, no phone numbers, no names. Do not use it to identify or contact individuals. An origin can be a personal website: removal requests go to lucashpissaia@gmail.com and take effect in the next monthly build.

Source and licence

• Derived from the HTTP Archive (https://httparchive.org) monthly crawls, public BigQuery dataset httparchive.crawl.pages. Every row carries this attribution in source.
• Detection is done by the HTTP Archive's open-source fork of Wappalyzer. Only detection results are served; detection rules, icons and descriptions are not redistributed. Technology names are trademarks of their owners and are used only to identify them.
• Popularity buckets come from the Chrome UX Report (Google), as included by the HTTP Archive.
• Licence: none published by the source. The HTTP Archive publishes no formal licence for its data. Its maintainers have said in public that "people are free to use the data however they want" and that attribution is appreciated (discussion). We do not claim a licence for this product. We have asked the HTTP Archive for written confirmation and have not received an answer yet; if it asks us to stop, the Actor is withdrawn.
• Not affiliated with or endorsed by the HTTP Archive, Google or Wappalyzer.
• Removal requests: write to lucashpissaia@gmail.com with the origin or domain. It goes into the opt-out list that every build applies before anything is published.
• Use: your own analysis, prospecting lists, models and products built on the results. Do not resell the raw rows in volume or as a substantially similar dataset or API.
• No warranty: provided as is, with the limitations above.

FAQ and support

How fresh is the data? Monthly. RUN_SUMMARY.latest_crawl is the crawl month and data_build_date the build date.

Can I check a site that is not in the list? Not in this version: there is no live detection. The domain is listed in not_found and not charged.

Why does changes return fewer rows than I expected? The default is min_confidence: both_clients, which drops the changes only one of desktop and mobile saw (42% of them), because those reverse far more often. Set any to include them.

Found a problem or need another field? Use the Issues tab.