polygon.io
Polygon.io, branded here as Massive, provides financial market data for stocks, options, futures, indices, forex, crypto, and related datasets. Its products deliver historical, real-time, and bulk-download market data for developers and analysts.
polygon.io (Massive) exposes a REST API, a WebSocket streaming API, an S3-compatible Flat Files endpoint, and a remote MCP server; all require Massive-issued credentials.
- Massive Remote MCP Serverdiscovered
- Massive WebSocket APIdiscovered
- Massive Flat Files S3 endpointdiscovered
- Massive REST APIdiscovered
Sign up or log in to your Massive/Polygon account, then open the API Keys dashboard to copy your API key. The REST docs say the same key can be sent either as the apiKey query parameter or as Authorization: Bearer <API_KEY>, and the WebSocket docs use it in the auth message payload.
Ensure your account has Flat Files access, then open the API Keys dashboard to obtain your S3 Access Key and Secret Key for the Flat Files S3-compatible endpoint. Use them together with endpoint https://files.massive.com and bucket flatfiles in your S3 client configuration.
Create a Massive account from signup, then add the remote MCP server https://mcp.massive.com/ in your MCP client and complete the browser sign-in flow when prompted. Massive's AI Tools docs state the hosted MCP server authenticates over OAuth and that there is no API key to copy or store.
conventions · 1/8 published
- integrations.json✗
/.well-known/integrations.json - llms.txt✓https://polygon.io/llms.txt
- API catalog✗
/.well-known/api-catalog - OpenAPI document✗
/api/schema/, /openapi.json, /swagger.json, /api/openapi.json, or /v1/openapi.json - MCP server card✗
/.well-known/mcp/server-card.json - OAuth protected resource✗
/.well-known/oauth-protected-resource - Agent card✗
/.well-known/agent-card.json - Agent skills✗
/.well-known/agent-skills/index.json
Publish these signals → /publishing