Live on Base mainnet · x402 v2SEO Authority API. Open-web authority, priced per call.
Most "domain authority" numbers are proprietary black boxes — someone else's crawl, someone else's formula, licensed by the seat. This one is computed from the current Common Crawl hyperlink graph, the open web's own link structure, refreshed with each release. No scraped Google data, no seats, no subscription: an agent (or a curl command) pays per question in USDC on Base, from half a cent.
And an honesty rule most SEO tools won't make: metrics we don't have are unavailable, never fabricated. The API reports its exact current graph coverage on every health check, and routes without a production data source stay unsold rather than returning invented numbers.
Ten endpoints, half a cent to fifteen cents
| Route | What it answers | Price |
|---|---|---|
| GET/v1/domain-authority | Authority score for any domain | $0.01 |
| POST/v1/authority-compare | Head-to-head authority comparison | $0.02 |
| POST/v1/url-seo-score | On-page SEO score for a URL | $0.01 |
| GET/v1/query-correct | Search-query spelling correction | $0.005 |
| GET/v1/query-expand | Query expansion & related terms | $0.01 |
| POST/v1/keyword-opportunity | Keyword opportunity scoring | $0.05 |
| POST/v1/competitor-gap | Competitor content-gap analysis | $0.10 |
| POST/v1/content-brief | Data-backed content brief | $0.10 |
| POST/v1/site-audit | Multi-signal site audit | $0.15 |
| POST/v1/internal-link-opportunities | Internal linking opportunities | $0.05 |
Drop it straight into your agent
The open-source MCP server @forgemeshlabs/seo-authority-mcp exposes all ten routes plus a free capabilities tool. Without a wallet key it returns the structured x402 challenge and spends nothing — safe to install and explore. With a key it settles automatically under a per-call spend cap (default $0.15), and it refuses to report success without a real transaction hash. Discovery metadata is published at /.well-known/x402.json for the standard agent indexes.