Thinking Machines Lab is an AI research-and-product company whose first publicly released product is Tinker, a managed training and fine-tuning API for open-weight models. Tinker enables researchers and developers to run custom post-training loops (SFT and RL-style loops) with low-level control over forward/backward passes, optimizer steps, sampling, and checkpointing while the vendor operates the distributed GPU infrastructure.
Vendor positioning uses the phrase "control without infrastructure," indicating users retain algorithmic control while the vendor manages clusters, scheduling, retries, and distributed systems reliability.