Founding Engineer, Backend

About Orthogonal

Orthogonal (YC W26) is building the infrastructure layer for AI agents to discover, access, and pay for APIs. We're starting with go-to-market, the APIs that power outbound, enrichment, and growth. We're two technical cofounders in San Francisco.

The Role

This is a founding role, not a maintain-the-codebase role. You'll own the systems that let thousands of AI agents discover, call, and pay for APIs in real time — and help define the architecture as we scale. You'll work directly with both founders.

What you'll do

• Design and scale the API gateway that meters and routes large volumes of agent traffic
• Build payment and settlement rails for agentic transactions (x402 and MPP/Tempo)
• Own agent authentication, credentials, and the credits/billing service
• Push Postgres for both write throughput and low-latency reads under heavy concurrency
• Harden the integrations layer (Composio) and our MCP server
• Ship to production daily; use AI tools heavily to build, debug, and iterate

Who you are

• Strong track record as a primary IC on medium-to-large backend projects
• Have designed, deployed, and operated distributed services in production
• Comfortable with Node/TypeScript and Postgres at scale
• Think about race conditions, throughput, and failure modes by instinct
• Self-directed and thrive with real ownership on a small team

Nice to have

• Payments, fintech, or high-throughput infrastructure experience
• Worked on API gateways, rate limiting, or usage metering
• Familiarity with AI agents, MCP, or LLM tooling
• Open source contributions or shipped side projects

Details