Discover domain relationships and connected sites via BuiltWith's relationship data, paid per call on Tempo L2.
What it does
The BuiltWith Relationships endpoint exposes BuiltWith's domain relationship discovery API through the Locus MPP (Micropayment Protocol). Given a domain, it returns related domains that share infrastructure, tracking codes, analytics IDs, or other technical fingerprints — useful for mapping corporate structures, affiliate networks, and shared ownership across websites.
This endpoint is part of a broader BuiltWith suite available via Locus MPP that includes domain tech profiling, technology lists, company-to-URL lookup, trends, trust signals, and more. The Relationships endpoint specifically accepts a domain lookup parameter with optional pagination (SKIP and AMOUNT, max 500 results per page). Each call costs 55,000 base units of pathUSD on Tempo L2, which equals $0.055 per request.
Payment is settled via the Tempo method (pathUSD on Tempo L2). The endpoint uses a POST method with a JSON body. Note that the probe returned 404 on HEAD/GET — this is expected since the endpoint only accepts POST requests as documented in the OpenAPI spec. The OpenAPI schema is well-defined with clear parameter descriptions, though response schemas are not documented beyond status codes.
Capabilities
Use cases
- —Mapping all domains owned by a single entity through shared analytics or tracking IDs
- —Discovering affiliate networks and partner sites connected to a target domain
- —Competitive intelligence — finding related properties of a competitor
- —Due diligence research to identify all web properties associated with a company
- —Fraud detection by linking suspicious domains through shared infrastructure
Fit
Best for
- —Agents needing programmatic domain relationship data without API key management
- —Pay-per-call access to BuiltWith relationship intelligence
- —Mapping corporate web property portfolios
- —Identifying hidden connections between domains
Not for
- —Bulk relationship scanning at high volume (per-call pricing adds up)
- —Real-time monitoring of domain changes (point-in-time lookups only)
- —Users who need response schema guarantees (response format undocumented)
Quick start
curl -X POST https://builtwith.mpp.paywithlocus.com/builtwith/relationships \
-H "Content-Type: application/json" \
-H "Authorization: <tempo-payment-token>" \
-d '{"LOOKUP": "example.com", "AMOUNT": "50"}'Example
Request
{
"SKIP": "0",
"AMOUNT": "100",
"LOOKUP": "shopify.com"
}Endpoint
Quality
OpenAPI spec is present with clear request schema and pricing, but the endpoint returned 404 on HEAD/GET (expected for POST-only). No response schema or example responses are documented. No crawled docs beyond the OpenAPI were available.
Warnings
- —Endpoint returned 404 on HEAD and GET probes; it only accepts POST per the OpenAPI spec — likely live but unconfirmed with a POST probe
- —Response schema is not documented — consumers cannot predict the shape of successful responses
- —Currency address 0x20c000000000000000000000b9537d11c60e8b50 assumed to be pathUSD (6 decimals) based on Tempo method context
Citations
- —The Relationships endpoint costs 55,000 base units via Tempo methodhttps://builtwith.mpp.paywithlocus.com
- —BuiltWith provides technology profiling across 100M+ websiteshttps://builtwith.mpp.paywithlocus.com
- —Additional documentation available at https://beta.paywithlocus.com/mpp/builtwith.mdhttps://builtwith.mpp.paywithlocus.com