Backend Engineer (OpenAI API)

Are you a backend engineer who takes pride in building clean, provider-agnostic systems at scale? Do you care deeply about developer experience, building interfaces that millions of users will interact with through a Python SDK, rather than just making something technically work?

This is an opportunity to join a fast-growing, profitable startup at the forefront of AI infrastructure, building the compliance and reliability layer that enterprise customers like Adobe, Netflix, and NASA depend on in production.

Backed by top-tier investors, the team has built the world’s most widely used LLM Gateway, a unified platform that gives developers secure, scalable access to every major LLM provider. Now, they’re building their second product, and looking for an AI Engineer to ensure the platform unifies the format for calling LLM APIs across the OpenAI and Anthropic spec.

As an early engineering hire, you’ll work directly with the CEO and CTO on writing transformations that convert API requests across provider formats, building provider-agnostic unification functionality, and maintaining an excellent LLM interoperability layer across LLMs, MCPs, and Agents.

If you’re looking for a role where your engineering work is used directly by thousands of engineering teams around the world, with real ownership over product decisions and not just implementation, this is an outstanding opportunity.

The Role

• Write transformations converting API requests from OpenAI/Anthropic spec to various LLM provider formats
• Build provider-agnostic unification functionality, including session management across non-OpenAI models
• Design systems supporting provider-level features at the gateway level (skills, compaction, batches)
• Support a wide range of MCP Auth flows and enable various Agent use-cases
• Shape developer experience for millions of users via the Python SDK

• 1+ years of backend or full-stack experience with production systems
• Experience working with the OpenAI API, understands the nuances between /chat/completions and /responses
• Eager to talk to users and help solve real problems
• CS degree or equivalent from a top 30 program in the US or Canada

4.04.0 out of 5 stars San Francisco, CA $200,000 - $250,000 a year - Full-time, The salary advertised is the bracket available for this position. The actual salary paid will be dependent on your level of experience, qualifications and skill set and will be decided by our client, the employer. Rise are not responsible or liable for any hiring decisions made by the end client.