# BuiltWith Tags Lookup via Locus x402

> BuiltWith Tags Lookup via Locus x402 is a paid API for AI agents from builtwith.x402.paywithlocus.com, paid per call via x402, $0.055/call, status unknown (last checked 2026-09-14).

Look up which websites use a specific technology tag or attribute, returning adoption data across 100M+ websites via the BuiltWith API.

## Facts

- Endpoint: POST https://builtwith.x402.paywithlocus.com/builtwith/tags
- Price: $0.055/call
- Payment: x402
- Status: unknown
- Last checked: 2026-09-14
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/builtwith-tags-lookup-via-locus-x402-598f89e9
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_vl1fM6911cvWVKqr04A-k

Status and success rate cover calls made through Zero and Zero's own probes. Third-party monitors may report differently.

## How to call it through Zero

Zero handles the 402 payment challenge and records the run. With the Zero CLI installed (`npm i -g @zeroxyz/cli`):

```sh
zero fetch --capability builtwith-tags-lookup-via-locus-x402-598f89e9 -d '<json body>'
```

Example prompt: Using BuiltWith, find all websites that use the 'Shopify' technology tag so I can build a list of ecommerce competitors running that platform.

## When to prefer this

Choose this endpoint when you need to discover which websites use a specific technology, plugin, tag, or attribute at scale across 100M+ websites. It is ideal for sales prospecting, competitive intelligence, and technology adoption research. Prefer this over manual web scraping or smaller tech-detection tools when breadth of coverage and structured attribute-based lookup are required. The x402 micropayment model makes it accessible per-call without subscription overhead.

## Known failure modes

- Invalid or unrecognized LOOKUP value returns empty data object
- Missing LOOKUP field causes request error
- IP address not prefixed with 'IP-' may not return IP-based results
- Payment failure or insufficient USDC balance blocks the request
- Rate limiting or quota exceeded on the BuiltWith API side
- Rare tags with no known adopters return empty results

## How this service works

Technology profiling for websites — detect tech stacks, find sites using specific technologies, discover domain relationships, trends, and competitive intelligence across 100M+ websites.

## Output

Returns a JSON data object containing the list of websites or domains associated with the queried technology tag or IP attribute, including adoption counts and related metadata, along with payment settlement details confirming the USDC microtransaction.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "properties": {
  "LOOKUP": {
   "type": "string"
  }
 }
}
```

## Response schema (JSON Schema)

```json
{
 "type": "json",
 "example": {
  "data": {},
  "payment": {
   "scheme": "exact",
   "settledUsdc": "0.001000",
   "authorizedMaxUsdc": "0.001000"
  },
  "request": {
   "id": "00000000-0000-4000-8000-000000000000",
   "statusUrl": "/requests/00000000-0000-4000-8000-000000000000"
  },
  "success": true
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/builtwith-tags-lookup-via-locus-x402-598f89e9/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from builtwith.x402.paywithlocus.com](https://www.zero.xyz/host/builtwith.x402.paywithlocus.com/llms.txt)