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GET
Categories
The Index is organized into 22 categories spanning the modern developer stack — from AI/LLM infrastructure to payments, auth, observability, and everything in between. Call GET /categories to get a live count of services per category — or use the gravity_index_list_categories MCP tool.

Authentication

Send your publisher key as the X-API-Key header or as a platform_api_key query parameter. One of the two is required; requests without a valid key are rejected with 403.
string
Publisher API key. Alternative to the platform_api_key query parameter.
string
Publisher API key. Alternative to the X-API-Key header.

Response

array
name and service_count for every category, sorted alphabetically.
number
Total number of services in the Index.

Example

Counts update whenever new services are added. The snapshot above reflects the initial public catalog (493 services, April 2026).

Categories at a glance