.txt (Outlines)

.txt builds software that constrains language-model outputs to schemas and grammars, helping developers integrate generated text into applications. Its Outlines library provides structured generation, while its commercial products serve application teams and inference providers. These include a hosted API, replacements for self-hosted vLLM, SGLang and TensorRT-LLM servers, and three integration libraries: dotjson for JSON Schema, dotgrammar for context-free grammars and dotlambda for function calling.

Co-founders Rémi Louf, Dan Gerlanc and Brandon Willard developed the approach after encountering problems extracting structured information from GPT-4 at Normal Computing; Louf is CEO. Their work draws on statistical modelling and compiler technology. Louf and Willard’s 2023 research reformulated text generation as transitions through a finite-state machine, using an index over a model’s vocabulary to guide generation with regular expressions and grammars. Implemented in Outlines, this model-agnostic approach applies constraints during generation.

The company reported more than 65 million Outlines downloads in 2026. Its commercial distribution extends beyond the library: api.dottxt.ai offers an OpenAI-compatible endpoint served by inference partner Doubleword, with usage charged per token. Teams can therefore access its constrained-decoding technology through hosted inference or integrate it into infrastructure they operate.