# BuiltWith Relationships API

> BuiltWith Relationships 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).

Returns relationship and network data for a given domain, revealing connected domains and technology ownership patterns

## Facts

- Endpoint: POST https://api.builtwith.com/agent/relationships
- 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-relationships-api-d800be30
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_ZCxINylhgMAQwgf3BU7lY

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-relationships-api-d800be30 -d '<json body>'
```

Example prompt: Can you use BuiltWith to pull the domain relationships for shopify.com — I want to see what other domains or properties are connected to it?

## When to prefer this

Choose this endpoint when you need to discover the network of domains related to a given site — such as finding sister properties, uncovering hidden corporate digital footprints, or doing competitive/M&A due diligence. Prefer this over a general technology lookup when the goal is mapping domain-to-domain relationships rather than just identifying technologies on a single site.

## Known failure modes

- Empty Results array if no relationship data exists for the domain
- Invalid domain format returns a validation error
- Obscure or brand-new domains may return sparse or no data
- Network timeouts on large relationship graphs
- Malformed domain input (e.g., including URL path) causes errors

## How this service works

BuiltWith API Overview

## Output

A JSON object with a Results array containing relationship and network data associated with the queried domain, including connected domains and ownership linkage signals as available in the BuiltWith dataset.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "properties": {
  "domain": {
   "type": "string",
   "maxLength": 253,
   "minLength": 1,
   "description": "Domain name to research, for example example.com. Do not include a URL path."
  }
 }
}
```

## Response schema (JSON Schema)

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

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/builtwith-relationships-api-d800be30/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)