Senior Software Engineer, AI - Simulation

Experience building and owning complex software systems where correctness, reliability, and failure modes are critical.

Experience designing test, simulation, or validation systems for non-deterministic or high-stakes environments.

Strong systems thinking, with the ability to decompose complex problems and reduce incidental complexity.

Demonstrated ability to influence product architecture through quality, reliability, and launch-readiness constraints.

Comfort operating with real authority and cross-team influence, including blocking launches and partnering across seniority levels to raise the quality bar.

The expected salary range for this role is $192,000 - $240,000. However, the starting base pay will depend on a number of factors including the candidate’s location, skills, experience, market demands, and internal pay parity. Depending on the position offered, equity and other forms of compensation may be provided as part of a total compensation package.

Please be aware, job-seekers may be at risk of targeting by malicious actors looking for personal data. Brex recruiters will only reach out via LinkedIn or email with a

brex.com

domain. Any outreach claiming to be from Brex via other sources should be ignored.

You’ll own Brex’s simulation and validation platform for AI-powered products. Your mandate is simple and unforgiving: ensure that every AI surface at Brex is continuously scrutinized under extreme, realistic conditions — and that teams can ship with confidence because of it.

You’ll build a system that uses synthetic data and scenario generation as a recursive self-improvement loop. Product teams will rely on it to catch regressions before customers do, to validate new capabilities safely, and to evolve prompts and agent behavior continuously. This platform will run against isolated, ephemeral environments that mirror production closely enough to matter.

This is not a research role. It’s about exercising real products, breaking them creatively, and forcing the organization to get better.

Evolve and scale a simulation and validation platform to continuously stress-test Brex’s AI products using large-scale synthetic data.

Develop evaluation mechanisms to detect regressions, edge cases, and failure modes in non-deterministic systems prior to customer impact.