Thinking Machines Lab

Thinking Machines Lab is the AI startup founded in early 2025 by Mira Murati, OpenAI's former CTO, with a founding team drawn heavily from OpenAI's research leadership, including John Schulman. It raised roughly $2 billion in the largest seed round in history at a reported $12 billion valuation before releasing any product. Its first offering, Tinker, is an API for fine-tuning open-weight models, signaling a focus on customization and human-AI collaboration rather than a frontier chatbot race.

Murati left OpenAI in September 2024 and unveiled Thinking Machines Lab in February 2025, recruiting a striking share of OpenAI's senior research staff — co-founder John Schulman (a ChatGPT architect and RLHF pioneer) among them. The company's stated mission centers on making AI systems more understandable, customizable, and broadly capable through open science and products that support human-AI collaboration.

Its seed round, led by Andreessen Horowitz with participation from NVIDIA and other strategic investors, set records for a pre-product company and underscored how founder pedigree drives AI capital allocation. The lab publishes research through its "Connectionism" blog, including influential work on deterministic LLM inference.

Tinker, launched in October 2025, lets researchers and developers fine-tune open-weight models (such as Llama and Qwen lines) through a simple API while the company manages distributed training infrastructure — a wedge into the post-training market rather than a head-on frontier-model play.