OuteTTS
Pure language modeling approach to TTS without traditional audio codecs.
About
OuteTTS takes an unusual approach to speech synthesis, treating it purely as a language modeling problem: audio is produced through next-token prediction rather than a conventional pipeline of separate acoustic models and vocoders. The project from OuteAI ships models at 0.6B and 1B parameters across several releases up to version 1.0, supports voice cloning through custom speaker profiles created from reference audio in a few lines of code, and generates clips of roughly 42 seconds per run. It is distributed as both a Python package on PyPI and a JavaScript package on npm, and runs on many backends including llama.cpp, Hugging Face Transformers, ExLlamaV2, vLLM, and Transformers.js, with acceleration on CUDA, ROCm, Apple Metal, and Vulkan hardware. Because the models behave like ordinary language models, they also load in third-party runtimes such as KoboldCPP. The lightweight footprint and broad backend support appeal to developers who want local, open text-to-speech without heavyweight dependencies.
Should you use OuteTTS?
Pick it when
Pick OuteTTS when you already run llama.cpp, vLLM, ExLlamaV2, or Transformers.js and want TTS that loads like any other language model, with speaker profiles for cloning and an npm package for browser or Node apps.
Look elsewhere when
Skip it if you need commercial terms without reading each checkpoint: the Llama-based 1B release of version 1.0 is CC-BY-NC-SA while the 0.6B one is Apache-2.0. Each run also caps near 42 seconds, so long narration needs chunking.
Alternatives to OuteTTS
- Orpheus TTS
Also a speech LLM served through vLLM or llama.cpp GGUF, with emotion tags and Apache-2.0 weights, but English focused and larger at 3B.
- Llasa
Same speech-as-tokens idea at 1B to 8B scale with published training code, but its weights are non-commercial and it needs a CUDA GPU.
- Kokoro TTS
Much smaller and faster on CPU with Apache-2.0 weights, but fixed voices only, so you lose OuteTTS's speaker profile cloning.
- Spark-TTS
Qwen2.5 based 0.5B speech LLM with Apache-2.0 code and control over gender, pitch, and rate, though only Chinese and English.
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Details
- Category
- Text-to-Speech (TTS)
- Price
- Free
- Platform
- Local/Desktop
- Difficulty
- Intermediate (3/5)
- Minimum VRAM
- 4 GB
- Added
- Apr 3, 2026