Engineering Internship

Reason Machines is building the future of autonomous software engineering with Reason Agent. We are a small team in San Francisco building the coding agent that takes ownership of real engineering work.

Ara makes agent-assisted engineering reliable, from first prompt to verified pull request.

About the role

Own product, runtime, and production systems. Turn early ideas into dependable software with high autonomy. You will work across the product surface and the infrastructure behind long-running autonomous agent work.

What you'll do

• Build clear, dependable agent-assisted product experiences.

• Design and run the systems behind long-running agent work.

• Work directly with users and turn rough workflows into product.

• Raise the bar for quality, testing, verification, and operations.

You may be a fit if

• You have shipped substantial product or platform systems.

• You move comfortably between product, frontend, and backend.

• You care about dependable products, not just demos.

• You communicate clearly and enjoy hard trade-offs.

Why Ara

Coding is changing from a craft practiced one prompt at a time into an operating system for building. Ara turns an incoming signal, such as a GitHub issue, Jira or Linear ticket, Slack thread, alert, or prompt, into a verified, reviewed pull request. Every task gets an isolated workspace. Ara reproduces the problem, writes the fix, verifies it with tests and evidence, works through review feedback, and leaves behind memory for the next run.

We are a small YC P26 team in San Francisco. You will have high ownership, no layers between you and users, and the chance to shape the product, runtime, and engineering culture from the beginning. Exceptional craft, curiosity, and follow-through matter more than a perfect résumé.

Reason Agent is an autonomous software engineering platform: a distributed system that runs long-lived coding agents across persistent cloud sandboxes and local machines, with full tools, browser automation, and MCP integration.