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

$50–65/hrrate as listed

Build production-quality full-stack software on top of pre-release frontier models, then document where the models and integrations break. This is a 40 hour/week W-2 engagement through Cincinnatus LLC, embedded with an AI lab's GenAI engineering team, with observed rates of $50–65/hr.

Summary, eligibility guidance and screening preparation are prepared by Sidequest from the platform's posting. Check the source listing before applying.

The work

This is a build-first role rather than a pure annotation role. You write real software — services, internal tools, front ends, evaluation harnesses — against model APIs that haven't shipped yet, and the software is the instrument. When a tool-calling interface misbehaves, when a long-context request degrades, when generated code compiles but fails under load, your job is to isolate it, reproduce it, and write it up clearly enough for research to act on.

Day-to-day you can expect: standing up scaffolding around pre-release endpoints (tool interfaces, telemetry, harnesses), prototyping against requirements that change mid-sprint, and delivering working increments without a full spec. You report to the AI lab's engineering manager and coordinate with other engineers on architecture, code quality, and documentation. The cohort is deliberately staffed across language ecosystems — Python, Java, Rust, C#, C++, TypeScript — so depth in one plus working fluency in a second matters more than breadth in all.

What the screen looks for

Verifiable production history. 3+ years shipping software at a recognized organization, with specifics: what you owned, what scale, what broke.
Genuine full-stack coverage — backend APIs, a modern front-end framework, relational or document data stores, and cloud deployment you actually operated.
Cold-start speed. Concrete evidence you've landed meaningful code in an unfamiliar codebase within days, not months.
Written clarity. Expect to be asked to explain a technical decision in prose; vague answers under follow-up are the most common failure mode.
Career progression that reads as real, not lateral.

Logistics

Full-time, 40 hours/week, weekday-aligned with the client team — this is not a nights-and-weekends side engagement. Remote, with synchronous collaboration expected. Employment is W-2 through Cincinnatus LLC as employer of record (payroll, benefits, compliance), with placement into the AI lab's extended workforce. Pay in the $50–65/hr range has been observed for this listing; actual offers depend on level, language ecosystem, and the lab's requisition, and are set by the platform rather than guaranteed here.

What they look for

3+ years production software engineering at a recognized organization
Production depth in Python, Java, Rust, C#, or C++ plus working proficiency in a second
Full-stack range: backend APIs, React or equivalent, SQL/document databases, cloud deployment
Fast onboarding onto unfamiliar codebases with minimal ramp-up
Clear technical writing — failure-mode reports and design rationale
Availability for 40 hours/week on weekdays

Before you apply

Would you pass this screen?

Drawn from what this listing actually requires. Answered in your browser — nothing is sent to us, and we do not store your answers.

Have you spent at least 3 years of your professional career building and shipping production software at a recognized, top-tier technology organization?
3+ years production software engineering · required
Have you shipped production code in at least one of the following languages: Python, Java, Rust, C#, or C++?
Production depth in Python, Java, Rust, C#, or C++ · required
Can you write and debug code fluently in a second language from this list (Python, Java, Rust, C#, C++, or TypeScript), even if you haven't shipped as much production code in it?
Working proficiency in a second language from the listed stack · required
Have you built and deployed systems that span backend services or APIs, a modern frontend framework (React or similar), and a database (relational or document)?
Full-stack experience (backend, frontend, database) · required
Can you commit to and sustain 40 hours per week during US weekdays for the duration of this engagement?
Availability: 40 hours/week weekdays · required
Are you authorized to work in the United States and able to accept W-2 employment with Cincinnatus LLC?
US work authorization (W-2 position) · required

0 of 6 answered

Included with this listing

Interview prep — 10 questions

Matched to what this platform's screening actually measures. Answer each out loud in 60–90 seconds: claim → concrete example → implication.

What it tests: Whether the candidate has genuine full-stack experience spanning backend, frontend, and data layers — not isolated expertise in one tier — and whether they understand the integration surface where layers collide.
A strong answer: A specific system with a backend service (API, database schema, deployment), a frontend interface, and clear handoffs between them; the candidate should articulate why that particular architecture was chosen and how they debugged failures across layers.
Where people lose it: Describing a feature or tool built entirely in one language or on one tier (e.g., 'I built a Python script' or 'I worked on the React UI') without evidence of owning the full request-response cycle or database-to-UI flow.