# 3RD API, MCP server and authentication

3RD (get3rd.com) is the AI visibility platform. These are the addresses an agent uses to call it.

## Free sandbox

No account is required. POST [/v1/sandbox/keys](/v1/sandbox/keys) returns a sandbox key. GET [/v1/sandbox/visibility](/v1/sandbox/visibility) with that key in `X-API-Key` returns fixture visibility rows. The example key `3rd_sandbox_public_agent` works the same way. The description of the sandbox is at [/v1/sandbox](/v1/sandbox). These rows are fixture data, not a customer account's measurements.

## API

The Export API is read-only access to a brand's measurements. The OpenAPI document is [/openapi.json](/openapi.json). The canonical copy, which this host republishes, is https://app.get3rd.com/api/export/v1/openapi.json. Authenticate with an X-API-Key created in the 3RD app under Settings, for Looker Studio.

A short machine-readable description of the product is at [/v1/product](/v1/product). The same description is a GraphQL query at [/graphql](/graphql): every field is typed, and the schema publishes `@cost` and `@rateLimit` (60 requests per 60 seconds per IP). [/api/graphql](/api/graphql) serves that schema too.

## MCP server

The product MCP is https://app.get3rd.com/api/mcp. It speaks Streamable HTTP and requires OAuth. The server card, with the 3RD name, icon and description, is at [/server-card](/server-card) and [/.well-known/mcp/server-card.json](/.well-known/mcp/server-card.json).

The same server is the ChatGPT plugin: [3RD in the ChatGPT plugin directory](https://chatgpt.com/plugins/plugin_asdk_app_6ac5d73e05ac81919255bb8195b1ba21).

The documentation MCP is https://docs.get3rd.com/mcp. Its card is at [/.well-known/mcp/docs-server-card.json](/.well-known/mcp/docs-server-card.json).

Both are listed in [/.well-known/ard.json](/.well-known/ard.json) and [/.well-known/ai-catalog.json](/.well-known/ai-catalog.json).

## Authentication

[/auth.md](/auth.md) is the walkthrough: authorization code, PKCE S256, and where the metadata is published. The authorization server is https://app.get3rd.com/.well-known/oauth-authorization-server.

## Skills

Agents that already have a 3RD session use the skills at [/.well-known/agent-skills/index.json](/.well-known/agent-skills/index.json): visibility status, competitor trend, citation sources, content gaps and next actions.

## Documentation

The human documentation starts at https://docs.get3rd.com/llms.txt. The API and MCP guide is https://docs.get3rd.com/integrations/api-and-mcp.