JavaScript Framework Detector | React & Vue

Inspect framework signals across websites

JavaScript Framework Detector: Detect exposed React, Next.js, Vue and other JavaScript technology signals from supplied websites. Export framework and library columns for technical research. Does not execute page JavaScript or prove framework absence.

Start with a small example

1. Open Input, switch to JSON and paste the example below. Replace the example startUrls with your own research targets when ready.
2. Check the live Pricing tab and set a run spending limit.
3. Run the Actor, then open the Workflow output view. Inspect url, javascriptFrameworks, javascriptLibraries, uiFrameworks, webFrameworks, error.
4. Export JSON for nested data or CSV for a spreadsheet. Review a small sample before increasing the scope.

{
  "startUrls": [
    "https://nextjs.org",
    "https://nuxt.com",
    "https://www.gatsbyjs.com"
  ],
  "filterTechnologies": [
    "React",
    "Next.js",
    "Vue.js",
    "Nuxt.js",
    "Angular",
    "AngularJS",
    "Svelte",
    "SvelteKit",
    "Astro",
    "Gatsby",
    "Remix",
    "Ember.js",
    "Backbone.js",
    "Alpine.js",
    "SolidJS",
    "Qwik",
    "Preact",
    "Lit",
    "Stimulus",
    "htmx",
    "jQuery",
    "Vite",
    "webpack",
    "Emotion",
    "styled-components",
    "Tailwind CSS",
    "Bootstrap",
    "Material UI"
  ],
  "onlyMatching": false
}

At the rate checked September 9, 2026, 3 saved rows cost $0.009 in Actor event fees ($3.00 per 1,000 rows). Actual returned rows determine the event fee. Taxes and other account services may be separate.

What can I use it for?

• Developer-tool and platform marketing. If you sell to teams building with Next.js, Vue or Angular, this turns any domain list into the subset that actually uses your framework.
• Recruiting and staffing. Find companies whose public sites reveal the stack you place engineers for.
• Migration and modernisation sales. Sites still on AngularJS, Backbone or a five-year-old jQuery are candidates for a rebuild.
• Competitive and ecosystem research. Measure framework adoption across an industry, a region or a list of competitors.
• Agency due diligence. Audit a portfolio of client sites for outdated library versions before an engagement.
• Enriching your data. Add javascriptFrameworks and uiFrameworks columns to a spreadsheet of accounts in one run.

What data does it return?

One record per website:

Field	Meaning
url, finalUrl, statusCode, title	What you asked for, where it resolved to, and the page title
javascriptFrameworks	React, Next.js, Vue.js, Nuxt.js, Angular, Svelte, Astro, Gatsby and so on
javascriptLibraries	jQuery, Lodash, Alpine.js, htmx, GSAP and similar
uiFrameworks	Tailwind CSS, Bootstrap, Material UI, Bulma and similar
webFrameworks	Server-side frameworks where exposed, e.g. Ruby on Rails, Django, Laravel, Express
programmingLanguages	PHP, Python, Ruby, Java, Node.js where exposed
paas, hosting, cdn	Where it runs, for context — Next.js on Vercel, Astro on Netlify
matchesFilter	true when the site uses any of the frameworks you listed under Frameworks to look for
matchedTechnologies	Which listed frameworks were found
technologyCount	Total technologies detected
technologies	The complete list with categories, versions and confidence scores — this is where version numbers appear
error	null on success, otherwise why the site could not be checked

Sites that time out or refuse the connection are still returned with an error, so input and output line up one to one.

Illustrative output

Values explain the output shape; they are not a live result or guaranteed field coverage.

{
  "url": "https://nuxt.com",
  "finalUrl": "https://nuxt.com/",
  "statusCode": 200,
  "title": "Nuxt: The Progressive Web Framework",
  "javascriptFrameworks": "Nuxt.js, Vue.js",
  "javascriptLibraries": null,
  "uiFrameworks": null,
  "paas": "Vercel",
  "matchesFilter": true,
  "matchedTechnologies": ["Nuxt.js", "Vue.js"],
  "technologyCount": 4,
  "technologies": [
    { "name": "Nuxt.js", "categories": ["JavaScript frameworks", "Web frameworks"], "version": null, "confidence": 100, "website": "https://nuxt.com" },
    { "name": "Vue.js", "categories": ["JavaScript frameworks"], "version": null, "confidence": 100, "website": "https://vuejs.org" }
  ],
  "error": null
}

How to use it

1. Paste your domains under Websites to check, upload a file, or pass them through the API as startUrls. Bare domains like example.com are fine.
2. Leave Frameworks to look for at its defaults for a broad inventory, or narrow it to one framework to build a targeted list.
3. Switch on Store only matching websites to pay only for sites that use the frameworks you listed and discard the rest.
4. Click Start and download the results as JSON, CSV or Excel from the Output tab, or read them from the dataset via the API.

Input example

{
  "startUrls": [
    "https://nextjs.org",
    "nuxt.com",
    "https://www.gatsbyjs.com"
  ],
  "filterTechnologies": ["Next.js", "Nuxt.js", "Gatsby"],
  "onlyMatching": false
}

Raise Max concurrency for large lists. Turn on Proxy configuration only if some sites block the platform's IP range — most do not.

How detection works

Frameworks leave distinctive traces in the page's first response: the __NEXT_DATA__ script and /_next/static/ asset paths for Next.js, __NUXT__ for Nuxt, data-reactroot and React's runtime chunks, ng-version attributes for Angular, svelte- class prefixes, astro-island custom elements, the ___gatsby root and so on. The detector fetches each homepage once and checks the headers, cookies, HTML, script sources, inline scripts and meta tags against more than 7,600 technology fingerprints, adding implied technologies — Next.js implies React — at a lower confidence so you can tell direct evidence from inference.

Because the page's JavaScript is never executed, a framework that leaves no trace in the server-rendered HTML and only reveals itself at runtime can be missed. For the mainstream frameworks that is rare: their build output is recognisable in the markup and asset paths. The trade-off buys speed and a much lower cost per site.

The fingerprint database is the open-source webappanalyzer technology dataset, used under the GNU GPL v3. The matching engine in this actor is original code.

Pricing

You pay per website saved to the dataset. With Store only matching websites on, that means per matching site; with it off, per site checked. There are no subscriptions, seats or minimums, and you can cap the maximum spend of a run before it starts.

Scope and responsible use

The actor requests only the publicly served homepage of each URL you provide, exactly as a browser would. It requires no login, no cookies and no credentials, does not execute or download the site's scripts beyond reading the page, does not crawl beyond the page you give it, and does not attempt to bypass any access control or bot-protection challenge. You are responsible for using the results in accordance with the laws that apply to you and the terms of the websites you check.

Limitations

• Heavily bundled or obfuscated builds can hide framework signatures; the detector reports what it can see and never guesses.
• Version numbers are reported only when a site publishes them in a script path, meta tag or comment.
• Very large media homepages that deliberately stall automated traffic can exceed the request timeout; they come back as rows with an error rather than being dropped.
• Only the URL you supply is fetched; a marketing site and its application often use different stacks.

Something not detected?

Open an issue on this actor's Issues tab with the URL and the framework you expected. Include a reproducible input and the expected signal so the report can be investigated.

Interpret empty results and errors

A null technology field means no recognized signal was found in the inspected response; it does not prove absence. A returned error means that URL was not successfully analyzed. With onlyMatching: true, non-matches and errors are omitted from the dataset, so a zero-row result cannot distinguish an unavailable site from no matches. Start with onlyMatching: false when checking coverage.

Every saved row, including an error row, incurs the configured per-row event fee. Proxy selection and run duration can affect operating costs. Do not increase concurrency or enable a more expensive proxy merely to work around an unclear result.

For a reproducible problem, open this Actor’s Issues tab with a small public input, expected behavior and relevant error text. Remove tokens and confidential information. No response-time or uptime guarantee is offered.

Use the result in an automation

In Make or n8n, use the Apify integration to run this Actor with the same JSON input, wait for completion, then retrieve its default dataset. Route failed runs and error rows to a review step before sending valid results to your spreadsheet or CRM. Scheduling does not make these Actors emit only new records: deduplicate downstream using the source URL or record ID.

For Node.js, install the official apify-client package and set your own APIFY_TOKEN environment variable. The following example starts a paid run with a small spending limit.

import { ApifyClient } from 'apify-client';
const client = new ApifyClient({ token: process.env.APIFY_TOKEN });
const input = {
  "startUrls": [
    "https://nextjs.org",
    "https://nuxt.com",
    "https://www.gatsbyjs.com"
  ],
  "filterTechnologies": [
    "React",
    "Next.js",
    "Vue.js",
    "Nuxt.js",
    "Angular",
    "AngularJS",
    "Svelte",
    "SvelteKit",
    "Astro",
    "Gatsby",
    "Remix",
    "Ember.js",
    "Backbone.js",
    "Alpine.js",
    "SolidJS",
    "Qwik",
    "Preact",
    "Lit",
    "Stimulus",
    "htmx",
    "jQuery",
    "Vite",
    "webpack",
    "Emotion",
    "styled-components",
    "Tailwind CSS",
    "Bootstrap",
    "Material UI"
  ],
  "onlyMatching": false
};
const run = await client.actor('keystonelabs/javascript-framework-detector').call(input, {
  memory: 512, timeout: 180, maxTotalChargeUsd: 0.10
});
if (run.status !== 'SUCCEEDED') throw new Error('Run did not succeed: ' + run.id);
const { items } = await client.dataset(run.defaultDatasetId).listItems({ limit: 100 });
console.log(items);

The first 100 rows are retrieved in this example. Use the dataset API pagination for a larger result. Keep credentials out of shared inputs and source files.

A useful next step

• Website Tech Stack Detector | Bulk URL Lookup: qualify a website list by its technology. This is a separate Actor with its own input and price.

Understand the run at a glance

Open Run summary in Output for counts of unique URLs, analyzed responses, failures, matches and saved rows. It remains useful when onlyMatching produces an empty dataset. The summary is written at normal completion and does not add a billable dataset row. Failed or aborted runs may not have a final summary; check run status first. The summary contains counts only, not a second copy of scraped content.