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API Reference
Reference
SDKs
Reference

SDKs

SDKs for building with Keycard.

Pick a Keycard SDK based on what you build. Most teams start with the MCP package to add OAuth to MCP servers. Other packages cover edge runtimes, custom OAuth flows, and agent-to-agent delegation.

Build MCP servers

Section titled “Build MCP servers”
BUILD MCP SERVERS

Add OAuth to MCP servers. The most common Keycard use case.

MCPAdd OAuth to MCP servers. The most common starting point. Python, TypeScript, Go, and Ruby.
Cloudflare WorkersDeploy MCP servers or APIs on Cloudflare Workers. Mirrors the MCP package with isolate-safe caching for Workers. TypeScript.

Custom auth flows

Section titled “Custom auth flows”
CUSTOM AUTH FLOWS

Build custom OAuth flows and agent-to-agent delegation.

OAuth PrimitivesBuild custom OAuth flows outside MCP. Discovery, token exchange, JWT, and PKCE. Python, TypeScript, Go, and Ruby.
Agent-to-AgentBuild agent-to-agent delegation chains with the A2A protocol. Python, TypeScript, Go, and Ruby.

Source and packages

Section titled “Source and packages”
SOURCE & PACKAGES

Each card links to the SDK’s source repository. Install from the registry for your language: PyPI, npm, pkg.go.dev, or RubyGems. pkg.go.dev also hosts the full Go API reference.

Pythonkeycardai-oauth, keycardai-mcp, keycardai-fastmcp, keycardai-starlette, and keycardai-a2a on PyPI
TypeScript@keycardai/oauth, @keycardai/mcp, @keycardai/express, @keycardai/cloudflare, and @keycardai/a2a on npm
Gogithub.com/keycardai/go-sdk with oauth, mcp, and a2a packages
RubyThe keycardai-oauth, keycardai-mcp, and keycardai-a2a gems on RubyGems
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