Yoast is the maker of the world's most popular WordPress SEO plugin, active on over 13 million sites, and is part of Newfold Digital. Yoast provides developer APIs for integrating SEO metadata, structured data (Schema.org), meta tags, sitemaps, and SEO analysis into headless WordPress sites and third-party platforms. Most of that surface ships as plugin code and runs on the customer's own WordPress install: the Yoast REST API (/wp-json/yoast/v1/get_head plus yoast_head_json on WP posts and pages), the Schema Aggregator API that emits a site's whole Schema.org graph as JSON-L, the Surfaces, Metadata and Schema PHP APIs, and — since Yoast SEO 27.5 — three read-only WordPress Abilities that hand SEO, readability and inclusive-language scores to AI agents. Yoast additionally operates one hosted API of its own, the MyYoast Provisioning (Subscription) API at my.yoast.com, a partner-gated Basic Auth surface for resellers, backed by an OpenID Connect issuer with dynamic client registration, PKCE and DPoP. Key products include Yoast SEO Free, Yoast SEO Premium, Yoast SEO for Shopify, WooCommerce SEO, Local SEO, Video SEO, and News SEO.
Yoast publishes 12 API contracts indexed on the APIs.io network, including Pages API, Posts API, SEO Head API, and 9 more. Tagged areas include SEO, WordPress, Content Optimization, Schema, and Metadata.
The Yoast catalog on APIs.io includes 1 JSON-LD context and 2 Spectral governance rulesets.
Yoast’s developer surface includes documentation, engineering blog, pricing, API reference, getting-started guide, support, signup flow, and 51 more developer resources.
Regulatory Posture applies to this provider. Its tags matched the
Horizontal (data, software, accessibility, platform) regime, so
Regulatory Posture carries 15 points of the composite.
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applicability map is public and we will correct it.
Create-or-Update Ergonomics applies to this provider. This API accepts writes, so it
carries 10 points of the composite. It is scored from the published contracts
themselves: whether a caller can create-or-update in one call, whether the write accepts a key the caller already
holds, and whether the response says which branch ran. Without that, every write needs a search-and-branch in
front of it, and the first time that check is skipped a duplicate record is created.
Scored against the observed mean rather than raw — a provider at the catalog average is unchanged by this facet,
not penalised by it.
The six quality facets above are damped to 75 points between them,
because the conditional facet above carries the other
25. That is why each facet's contribution is shown against a damped
maximum: raising a quality facet moves the composite by 75% of its nominal
weight, not 100%. The full arithmetic is at apis.io/rating/.
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Agent readiness — checks not met, largest first (exact, from this profile):
MCP Server+12 pts — deployment.mode + probe verdict on the mcp/ manifest, not the pointer; an unprobed slug falls back to authorship
Idempotency+9 pts — OpenAPI mutating operations declare an idempotency key — a header, a request-body property, or a named de-duplication token whose own description says so (verified); else common[].type matches /idempoten/i (documented)
A2A Agent Card+8 pts — a2a/-a2a.yml manifest, graded on conformance.grade against A2A 1.0.0
Typed Event Surface+6 pts — AsyncAPI document, OR webhooks/callbacks objects in the as-published OpenAPI, OR common[].type includes Webhooks
Pagination+5 pts — share of collection GETs (an array, or one wrapped in data/items/results ...) that declare a page/limit/offset/cursor parameter, a Link header or a next/cursor field; na with no collection GETs
Protected Resource Metadata+5 pts — a served /.well-known/oauth-protected-resource carrying `resource` (documented), and naming its authorization_servers (verified)
4 more unmet checks in the Agent Readiness table above.
Kin Score — facets with the most composite points still available (weight × headroom):
The Kin Score Market layer reads a provider inside its market:
its position, and how deep its integrations go. Depth is only comparable within a position. Provisional and unweighted:
not part of the Kin Score or agent readiness.
Registered MCP server and declares compatibility are report only — not weighted.
Undeclared means we found nothing we can read, so there is no number: we never infer integrations.
Standards this provider implements or carries. De facto ones are profiled and measured by the API Commons; formal ones come from the standards directory and are linked by the provider's own tags. The evidence column says how each claim was established — not that it was made.
The Yoast Surfaces API provides a PHP interface for retrieving SEO metadata programmatically within WordPress. It exposes the YoastSEO() surface with methods to get metadata for...
The Yoast Metadata API provides a PHP interface to add, alter, or remove metadata in the of a WordPress document. Developers can hook into Yoast's meta tag output pipeline to c...
The Yoast Schema API provides a PHP interface for customizing the Schema.org JSON-LD structured data output generated by Yoast SEO. Developers can add, remove, or modify schema ...
Yoast SEO registers its content-analysis results as WordPress Abilities (the Abilities API introduced in WordPress 6.9), making them discoverable and executable over the WordPre...
Overlays applied on top of this provider's contracts. Each card says who wrote it: a document the provider publishes, or one API Evangelist derived or generated.
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