Software Engineer RL Environments

Company: AfterQuery
Location: San Francisco CA (in person)
Compensation: $260000 - $290000 base profit share (around 150% of base per the company) competitive equity
Employment Type: Full-time
Visa Sponsorship: H-1B O-1 OPT

AfterQuery is an applied research lab that curates the datasets RL environments and evaluation infrastructure frontier AI labs use to build better models working with leading AI labs and companies including Nvidia Thinking Machines Lab and Legora.

Founded in 2025 AfterQuery reached a $100M revenue run rate within about a year and recently raised at a $3.2B valuation making it the fastest unicorn in Y Combinator history.

As a Software Engineer on Environments you will design the datasets and evaluation rubrics that directly shape how frontier models learn. You will work hands-on with research teams at top AI labs experiment with data-collection strategies diagnose model failure modes and build metrics that show whether a model is actually improving moving from hypothesis to live experiment quickly with output feeding directly into training runs at scale.

• Design data slices that expose meaningful model failure modes across domains such as finance code and enterprise workflows.
• Build and refine evaluation rubrics and reward signals for RLHF and RLVR pipelines.
• Model annotator behavior and run experiments to improve model capabilities.
• Develop quantitative frameworks for dataset quality diversity and downstream impact on alignment and capability.
• Create and manage real-world and synthetic data pipelines.
• Translate lab research teams training objectives into concrete data and evaluation specifications.

• 1-4 years of engineering experience
• Strong software engineering fundamentals and comfort running fast hypothesis-driven experiments
• Interest in RL evaluation and data for frontier model training
• Ability to work in person in San Francisco

Profit share (around 150% of base per the company) competitive equity and direct work with the worlds leading AI labs.

REVENUE: 16.5% of first-year salary. Est. fee per hire $43K-$48K; 3 seat(s) up to $136K if all filled.

TARGET COMPANIES (suggested): Scale AI Surge AI Mercor Snorkel AI Jane Street Citadel Hudson River Trading. DO NOT SOURCE: OpenAI (client do-not-source rule).

BEST-FIT CANDIDATE: 1-4 yrs; strong SWE fundamentals; RL/evals/data interest; visa: H-1B O-1 OPT; location: SF in person. Company prefers top-university top-quant or founding-engineer signal; do-not-contact OpenAI employees (sister-role rule).