JustusĀ Mattern
Summary
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RockstarJustus Mattern is a founder-engineer with three years of applied AI and systems experience, currently co-founding Proximal to build superhuman coding agents. He was the first post-training hire at Prime Intellect and a core contributor to prime-rl and INTELLECT-2, a globally distributed reinforcement-learning reasoning model. Prior ventures include a YC-backed pivot at Revideo where he shipped a browser animation library and cloud rendering used in production, and early ML work deploying on-device speech models and LLM fine-tuning platforms. His background blends physics and computer science from RWTH Aachen and TU Darmstadt with research at the Max Planck Institute on causal inference, differential privacy, and provable robustness. Comfortable moving between research and product, he repeatedly turns cutting-edge ML research into deployable systems. One less obvious strength: he has deep hands-on experience optimizing distributed training and inference pipelines across both cloud and edge environments.
3 years of coding experience
Github Skills (27)
agentic10
state-space9
gpt8
cuda8
inference8
llama8
llm8
amd8
tinker8
ssm8
openai8
pytorch8
transformer7
fine-tuning6
tpu6
Programming languages (5)
Github contributions (5)
Proximal-Environments/revideo-env
Sep 2025 - Oct 2025
Contributions:30 PRs, 12 pushes, 142 branches in 10 days
Proximal-Labs/prime-rl-clone-5
Aug 2025 - Aug 2025
Contributions:320 branches, 1 tag, 3 comments in 1 day
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