# BuiltWith Tags Lookup API

> BuiltWith Tags Lookup API is a paid API for AI agents from api.builtwith.com, paid per call via x402, $0.0495/call, status unknown (last checked 2026-09-14).

Looks up websites or IPs associated with a specific BuiltWith tag or technology attribute

## Facts

- Endpoint: POST https://api.builtwith.com/agent/tags
- Price: $0.0495/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-api-30d818d6
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_WPDYAspzlXfdBmLYBtk6N

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-api-30d818d6 -d '<json body>'
```

Example prompt: Use BuiltWith to look up which websites are associated with the tag 'IP-75.126.76.154' and show me the results.

## When to prefer this

Use this endpoint when you need to discover which websites are associated with a specific BuiltWith technology tag or IP attribute. Prefer this over general web scraping when you need structured, pre-indexed technology adoption data from BuiltWith's database. Best suited for competitive intelligence, lead generation by technology stack, or mapping IP addresses to hosted websites.

## Known failure modes

- Empty Results array if no websites are associated with the given tag
- Invalid or unrecognized tag format returns empty or error response
- Tag string exceeds 300 characters or is empty — validation error
- Payment failure via x402 protocol prevents API access
- Rate limiting or authentication issues returning HTTP error codes

## How this service works

BuiltWith API Overview

## Output

A JSON object with a 'Results' array containing websites and associated metadata linked to the queried BuiltWith tag or attribute. The number and detail of results vary based on the tag and available data in the BuiltWith database.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "properties": {
  "lookup": {
   "type": "string",
   "maxLength": 300,
   "minLength": 1,
   "description": "BuiltWith tag or attribute, for example IP-75.126.76.154."
  }
 }
}
```

## Response schema (JSON Schema)

```json
{
 "type": "json",
 "example": {
  "Results": []
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/builtwith-tags-lookup-api-30d818d6/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from api.builtwith.com](https://www.zero.xyz/host/api.builtwith.com/llms.txt)