# BuiltWith Relationships

> BuiltWith Relationships is a paid API for AI agents from BuiltWith at builtwith.mpp.paywithlocus.com, paid per call via MPP, $0.055/call, not verified (last probed 2026-10-12); live alternatives: Stable Domains Availability Checker ($0.05) and NetIntel Bulk Domain Availability Check ($0.1).

Agents call it through Zero, which pays per call: no API key and no wallet of your own. New accounts start with $5.

Live alternatives for the same use case:
- [Stable Domains Availability Checker](https://www.zero.xyz/c/stable-domains-availability-checker-d9c6e557) ($0.05)
- [NetIntel Bulk Domain Availability Check](https://www.zero.xyz/c/netintel-bulk-domain-availability-check-0a16e4f3) ($0.1)

Returns domain relationship data for a given domain, revealing co-hosted, co-owned, or otherwise linked domains using BuiltWith's technology profiling database.

## Facts

- Endpoint: POST https://builtwith.mpp.paywithlocus.com/builtwith/relationships?utm_source=zero.xyz
- Price: $0.055/call
- Payment: MPP
- Status: unknown
- Last checked: 2026-10-12
- Activations on Zero: 0
- Provider: BuiltWith
- Docs: https://api.builtwith.com
- Website: https://builtwith.com
- Tags: technology-profiling, tech-stack, competitive-intel, domains, data
- Canonical page: https://www.zero.xyz/c/builtwith-relationships-8699453a
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_ecmzxZtQ7ZCKO2vzy8aPp

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-8699453a -d '<json body>'
```

Example prompt: Can you look up all the domain relationships for shopify.com using BuiltWith? Show me the first 50 related domains.

## When to prefer this

Use this endpoint when you need to discover domains that are related to, co-hosted with, or otherwise linked to a target domain. Ideal for competitive intelligence, brand monitoring, domain network mapping, or identifying affiliated web properties. Prefer this over the Domain Lookup endpoint when the goal is relational discovery rather than tech stack profiling of a single domain.

## Known failure modes

- Invalid or malformed domain in LOOKUP returns an error or empty result set
- Domain not found in BuiltWith database returns empty relationships
- Exceeding AMOUNT limit of 500 per page may return an error
- Missing required LOOKUP field returns a validation error
- Network timeout for domains with very large relationship graphs

## How this service works

Discover domains related to a given domain through shared tracking codes, analytics IDs, ad accounts, and other identifiers.

## Output

A paginated list of domains that are related to the queried domain, including relationship signals such as co-hosting, shared technology footprints, or ownership links. Supports pagination via SKIP and AMOUNT parameters (up to 500 results per page).

## Example request

```json
{
 "SKIP": "0",
 "AMOUNT": "50",
 "LOOKUP": "github.com"
}
```

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "required": [
  "LOOKUP"
 ],
 "properties": {
  "SKIP": {
   "type": "string",
   "description": "Number of results to skip (pagination)"
  },
  "AMOUNT": {
   "type": "string",
   "description": "Number of results per page (max 500)"
  },
  "LOOKUP": {
   "type": "string",
   "description": "Domain to look up relationships for"
  }
 },
 "additionalProperties": true
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/builtwith-relationships-8699453a/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from builtwith.mpp.paywithlocus.com](https://www.zero.xyz/host/builtwith.mpp.paywithlocus.com/llms.txt)