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BuiltWith Relationships API
x402
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
Price / call$0.0495
Success—
StatusUnknown
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.
Example use cases
Competitive domain footprint mapping
“I'm doing competitive research on stripe.com — can you find all the related or connected domains associated with it using BuiltWith's relationships data?”
M&A digital due diligence
“We're evaluating an acquisition target — can you pull the BuiltWith relationship graph for acmecorp.com to see what other domains they own or are linked to?”
Brand protection and impersonation check
“I need to know if there are other domains out there connected to nike.com — can you run a relationships lookup on it to spot any affiliated or potentially impersonating properties?”
Technical details
Endpoint
POSThttps://api.builtwith.com/agent/relationshipsWhen to prefer
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.
Side effects
- 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
Input
Schema · Request body
| Field | Type | Description |
|---|---|---|
| domain | string | Domain name to research, for example example.com. Do not include a URL path. |
Output
Schema · Response
{
"type": "json",
"example": {
"Results": []
}
}Tags
x402
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