# JavaScript Framework Detector | React & Vue (`keystonelabs/javascript-framework-detector`) Actor

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.

- **URL**: https://apify.com/keystonelabs/javascript-framework-detector.md
- **Developed by:** [Nick McNemar](https://apify.com/keystonelabs) (community)
- **Categories:** Developer tools, SEO tools, Lead generation
- **Stats:** 2 total users, 1 monthly users, 100.0% runs succeeded, 0 bookmarks
- **User rating**: No ratings yet

## Pricing

$3.00 / 1,000 website checkeds

This Actor is paid per event. You are not charged for the Apify platform usage, but only a fixed price for specific events.

Learn more: https://docs.apify.com/actors/running/actors-in-store.md#pay-per-event

## What's an Apify Actor?

Actors are web data automations that power AI and operations. They run on the Apify platform to scrape websites, process data, connect APIs, and automate workflows.
In Batch mode, an Actor accepts a well-defined JSON input, performs an action which can take anything from a few seconds to a few hours,
and optionally produces a well-defined JSON output, datasets with results, or files in key-value store.
In Standby mode, an Actor provides a web server which can be used as a website, API, or an MCP server.
Actors are written with capital "A".

## How to integrate an Actor?

If asked about integration, you help developers integrate Actors into their projects.
You adapt to their stack and deliver integrations that are safe, well-documented, and production-ready.
The best way to integrate Actors is as follows.

- **AI agents and MCP clients** — the [Apify MCP server](https://docs.apify.com/integrations/mcp.md) at `https://mcp.apify.com` (remote, streamable HTTP, OAuth on first use).
- **Agentic workflows and local Actor development** — [Agent Skills](https://apify.com/.well-known/agent-skills/index.json) with the [Apify CLI](https://docs.apify.com/cli/docs.md): `npm install -g apify-cli`, then `apify login`.
- **JavaScript/TypeScript projects** — the official [JS/TS client](https://docs.apify.com/api/client/js/docs.md): `npm install apify-client`.
- **Python projects** — the official [Python client](https://docs.apify.com/api/client/python/docs.md): `pip install apify-client`.
- **Any other language** — the [REST API](https://docs.apify.com/api/v2.md).

For usage examples, see the [API](#api) section below.

For more details, see Apify documentation as [Markdown index](https://docs.apify.com/llms.txt) and [Markdown full-text](https://docs.apify.com/llms-full.txt).

# README

### 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.

```json
{
  "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.

```json
{
  "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

```json
{
  "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.

```javascript
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](https://apify.com/keystonelabs/tech-stack-detector): 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.

# Actor input Schema

## `startUrls` (type: `array`):

Domains or URLs to inspect. Each one becomes a result listing the frameworks and libraries found, with a matchesFilter flag for the ones you care about.

## `filterTechnologies` (type: `array`):

Frameworks, libraries and build tools that count as a match. The defaults cover the mainstream front-end stack; narrow the list to find, for example, every site running Next.js or Angular.

## `onlyMatching` (type: `boolean`):

Save only detected matches. Non-matches and error rows are omitted, so start with this off when reviewing coverage. Requires filterTechnologies.

## `maxConcurrency` (type: `integer`):

How many websites to analyze in parallel. Lower it if you are analyzing many pages on the same domain.

## `timeoutSecs` (type: `integer`):

Give up on a website after this many seconds. Large media and retail homepages can take 30 seconds or more to respond under load.

## `proxyConfiguration` (type: `object`):

Optional. Route requests through Apify Proxy if some target sites block your IP.

## Actor input object example

```json
{
  "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,
  "maxConcurrency": 20,
  "timeoutSecs": 45,
  "proxyConfiguration": {
    "useApifyProxy": false
  }
}
```

# Actor output Schema

## `results` (type: `string`):

Dataset of analyzed websites. Each item lists detected technologies with category, version and confidence.

## `workflowJson` (type: `string`):

Selected columns for this workflow. Inspect errors and missing values before using the data.

## `workflowCsv` (type: `string`):

Download the workflow columns as CSV. Use JSON for full nested arrays.

## `summary` (type: `string`):

Counts of analyzed, failed, matched, saved and omitted URLs. Use this to interpret a zero-row result.

# API

You can run this Actor programmatically using our API. Below are code examples in JavaScript, Python, and CLI, as well as the OpenAPI specification and MCP server setup.

## JavaScript example

```javascript
import { ApifyClient } from 'apify-client';

// Initialize the ApifyClient with your Apify API token
// Replace the '<YOUR_API_TOKEN>' with your token
const client = new ApifyClient({
    token: '<YOUR_API_TOKEN>',
});

// Prepare Actor input
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
};

// Run the Actor and wait for it to finish
const run = await client.actor("keystonelabs/javascript-framework-detector").call(input);

// Fetch and print Actor results from the run's dataset (if any)
console.log('Results from dataset');
console.log(`💾 Check your data here: https://console.apify.com/storage/datasets/${run.defaultDatasetId}`);
const { items } = await client.dataset(run.defaultDatasetId).listItems();
items.forEach((item) => {
    console.dir(item);
});

// 📚 Want to learn more 📖? Go to → https://docs.apify.com/api/client/js/docs

```

## Python example

```python
from apify_client import ApifyClient

# Initialize the ApifyClient with your Apify API token
# Replace '<YOUR_API_TOKEN>' with your token.
client = ApifyClient("<YOUR_API_TOKEN>")

# Prepare the Actor input
run_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,
}

# Run the Actor and wait for it to finish
run = client.actor("keystonelabs/javascript-framework-detector").call(run_input=run_input)

# Fetch and print Actor results from the run's dataset (if there are any)
print(f"💾 Check your data here: https://console.apify.com/storage/datasets/{run.default_dataset_id}")
for item in client.dataset(run.default_dataset_id).iterate_items():
    print(item)

# 📚 Want to learn more 📖? Go to → https://docs.apify.com/api/client/python/docs/quick-start

```

## CLI example

```bash
echo '{
  "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
}' |
apify call keystonelabs/javascript-framework-detector --silent --output-dataset

```

## MCP server setup

```json
{
    "mcpServers": {
        "apify": {
            "type": "http",
            "url": "https://mcp.apify.com/?tools=fetch-actor-details,keystonelabs/javascript-framework-detector"
        }
    }
}

```

The hosted server signs you in with OAuth on first connect, so no API token belongs in this config. Clients without OAuth support can send an `Authorization: Bearer <APIFY_API_TOKEN>` header instead, using a token from API & Integrations in Apify Console (https://console.apify.com/settings/integrations).

## OpenAPI specification

Download the OpenAPI definition: https://api.apify.com/v2/actors/s6euUQlPoPcPMfIle/builds/EfvJUOP4Fjs89rvhT/openapi.json