RealtimeTTS
Python library that streams LLM output into speech across 20+ TTS engines with automatic fallback.
About
RealtimeTTS solves a narrow but common problem: turning strings, generators, and LLM token streams into audible speech with as little latency as possible. The Python library sits as a glue layer above more than 20 engines, from free system voices, gTTS, and Edge through cloud APIs like OpenAI, Azure, ElevenLabs, Cartesia, and MiniMax to local neural models including Coqui XTTS, Piper, Kokoro, StyleTTS, Parler, Chatterbox, and Orpheus, with configurable fallback chains that switch engines automatically when one fails. Text can keep streaming in while audio is already playing, and the API covers pause, resume, stop, WAV file output, audio callbacks, voice switching, multiple output devices, and asynchronous playback. Installation is pip install with per-engine extras, such as realtimetts[system], realtimetts[coqui], or realtimetts[openai]. Hardware needs depend entirely on the chosen engine; system voices run anywhere while local neural engines benefit from CUDA acceleration. The MIT license permits commercial use, and with about 4,000 GitHub stars the library has become a standard way to pipe streaming LLM output into speech.
Should you use RealtimeTTS?
Pick it when
Pick RealtimeTTS when you are wiring a Python voice assistant and want LLM token streams spoken as they arrive, with one API over 20+ engines and automatic fallback from, say, a cloud voice to a local Piper or Kokoro model.
Look elsewhere when
Skip it if you need a TTS model itself, since it only orchestrates other engines, or a full voice agent with STT, turn detection, and telephony, where Pipecat or LiveKit Agents cover the whole pipeline.
Alternatives to RealtimeTTS
- Pipecat
Full STT, LLM, and TTS pipeline with WebRTC and telephony transports, more to learn but it handles the whole conversation, not just speech output.
- LiveKit Agents
Runs voice agents as WebRTC or phone participants with semantic turn detection, a heavier stack aimed at production calls rather than local playback.
- Kokoro TTS
A single local model you call directly, simpler than a glue layer when you only ever need one engine and no fallback.
- edge-tts
One free cloud voice backend with no API key, fine on its own for simple scripts, though RealtimeTTS can wrap it with fallback and streaming playback.
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Details
- Category
- Text-to-Speech (TTS)
- Price
- Free
- Platform
- Local/Desktop
- Difficulty
- Easy (2/5)
- License
- MIT
- Added
- Jul 29, 2026