Software Engineer, Full Stack (Python, Java, Rust, C#, C++)

What you'll do

You build software the way a customer would, but before the model ships: full-stack apps, services and internal tools running on a frontier lab's pre-release models. When the model or the integration falls over, you work out why and write it up for the research team.

The ad's responsibilities:

• Building and shipping apps and tools in Python, Java, Rust, C#, C++ or TypeScript that exercise the model end to end
• Integrating pre-release model APIs with the surrounding scaffolding: tool interfaces, evaluation harnesses, telemetry
• Diagnosing and documenting model and integration failure modes
• Prototyping quickly with minimal up-front spec
• Keeping code quality, architecture and docs consistent with the engineering manager and peers

This is the mid-level US tier of a three-listing family. The same work is offered at a senior level for 6+ years and as an India tier, with different pay.

Who qualifies

• 3+ years building and shipping production software at a recognised, top-tier organisation
• Production experience in one of Python, Java, Rust, C# or C++, and working proficiency in a second
• Full-stack range: backend services and APIs, React or equivalent, relational or document databases, cloud deployment
• Proven ability to ramp up fast on an unfamiliar codebase
• Demonstrable career progression
• 40 hours a week on weekdays
• Must be located in the United States

What it pays

$50–65 per hour, W-2 employment through Cincinnatus LLC, which provides payroll, benefits and compliance. The ad does not publish a payment schedule. The senior tier pays $90–110 for 6+ years; the India tier pays $25–30 for the same 3-year bar.

Worth knowing

Good:

• W-2 with benefits
• Hands-on access to pre-release frontier models
• A 3-year bar is achievable for many mid-level engineers

Less good:

• Full-time, 40 hours a week, US-only
• The rate is well below the senior tier, so experienced engineers near 6 years should check which listing they fit
• No duration published; the lab is not named
• Requirements shift fast, per the ad

About this listing

Posted on Mercor's platform, read on 24 September 2026. Employment is through Cincinnatus LLC, placed at a leading AI lab as extended workforce. Pay, location and qualifications are from the ad. See Mercor.