Proximal

§ Positioning

Code RL environment company pushing beyond deterministic tests toward fuzzy reward signals that capture code quality - fills a gap every lab building coding agents faces.

Best for · Labs that need verifiers for open-ended coding tasks, not just test-passing.

Team · Founded by Justus Mattern (ex-Prime Intellect RL infra; co-founded Revideo, YC S23), Navid Pour (ex-Cursor), and Calvin Chen. Team has published at leading research conferences.

Focus · Builds RL environments for coding agents, with a focus on fuzzy verifiers that reward code quality and maintainability beyond pass/fail tests.

Notable customers · Frontier labs (per company)

• Code · Math

  Prime Intellect

  the open-source backbone of the category

• Code · Software Engineering

  Mechanize

  deep, narrow, elite

• Long Horizon · Code

  Huzzle Labs

  environments + human data + evals in one stack

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