Definition
Plain language
Hugging Face's library for reinforcement-learning post-training of language models.
As stated in the literature
Transformer Reinforcement Learning, an open-source library for SFT, RLHF, and DPO-style post-training of language models.
Why it matters: It is one of the most widely used entry points for post-training open models, making advanced alignment techniques broadly accessible.
For example, a team can use TRL to apply DPO to a 7B-parameter open model with just a few hundred lines of code.
Heard on the show
“… DeepSpeed is the engine under three of the most popular SFT libraries — OpenRLHF, Llama-Factory, and TRL — every academic group running SFT through any of those libraries with CPU offloading turned on inherited …”Episode 009 — How Two Silent Library Bugs Quietly Invalidated a Wave of Reasoning Papers