Software Engineer, SDK
Keycard, US - Remote +1
The role
We're hiring a staff-level Software Engineer, SDK to own the libraries developers use to put Keycard in front of their agents and MCP servers. For most teams, the SDK is the first Keycard code they touch: a few lines that add OAuth to an MCP server, then token exchange so a tool can call GitHub or Google as the user.
Keycard is a control plane for agents: identity, credential exchange, delegation, policy, and audit. Our SDKs come in two kinds. The REST API clients for Python, TypeScript, and Go are generated from our OpenAPI spec. The agent SDKs are handwritten: OAuth primitives, MCP server and client auth, agent-to-agent (A2A) delegation (in preview), and integrations for frameworks like FastMCP, LangChain, Temporal, and Cloudflare Workers. The hard design work is on the handwritten side.
Python is the most complete today. TypeScript is in preview and working toward parity, and Go and Ruby are earlier. Keeping behavior consistent across four languages, while priorities differ and TypeScript comes next, is the core of the job. You'll work with founders, product, and the engineers building the services underneath.