TL;DR: Kitten TTS is an open-source, lightweight text-to-speech engine by KittenML. It runs on CPU, has 8 voices, weighs as little as 25 MB, and is completely free under Apache 2.0.

What is Kitten TTS?

Kitten TTS is a revolutionary open-source text-to-speech engine created by KittenML. Unlike the massive AI voice models that dominate the market, Kitten TTS takes a radically different approach: making TTS as small and efficient as possible while maintaining high quality.

At its core, Kitten TTS is a family of ONNX-based neural TTS models ranging from 15 million to 80 million parameters. For context, that is 5-60 times smaller than alternatives like Bark (1B params) or XTTS (500M params). The result is a TTS engine that runs smoothly on CPU, even on low-powered devices like Raspberry Pi.

Why Kitten TTS Matters

1. It Runs on CPU

Most high-quality TTS engines require GPU acceleration. Kitten TTS uses ONNX Runtime for CPU inference, making it accessible to anyone with a standard computer. No expensive graphics cards needed.

2. It is Truly Open Source

Released under the Apache 2.0 license, Kitten TTS can be used commercially, modified, and redistributed. There are no usage limits, no API keys, and no per-character charges.

3. It is Tiny

The smallest model (nano-int8) is just 25 MB. The largest (mini) is 80 MB. Compare this to WaveNet-style models that can be gigabytes in size. Kitten TTS is optimized for efficiency from the ground up.

4. It Has Character

With 8 distinct voices -- Bella, Jasper, Luna, Bruno, Rosie, Hugo, Kiki, and Leo -- Kitten TTS covers the full spectrum from warm narration to energetic social media content. Each voice has a distinct personality and use case.

Key Features

  • 8 built-in voices: Ready to use out of the box
  • Multiple model sizes: Mini (80M), Micro (40M), Nano (15M), Nano-int8 (25MB)
  • Speed control: Adjust from 0.5x to 2.0x
  • Text normalization: Built-in text preprocessing
  • Fine-tuning support: Train custom voice models
  • Batch generation: Generate multiple files programmatically
  • Python API: Simple, intuitive interface
  • Cross-platform: Windows, Mac, Linux, Docker

Getting Started in 30 Seconds

pip install soundfile
pip install https://github.com/KittenML/KittenTTS/releases/download/0.8.1/kittentts-0.8.1-py3-none-any.whl
from kittentts import KittenTTS
import soundfile as sf

model = KittenTTS("KittenML/kitten-tts-mini-0.8")
audio = model.generate("Hello world! This is Kitten TTS.", voice="Jasper")
sf.write("hello.wav", audio, 24000)

The 8 Voices

VoiceGenderStylePerfect For
BellaFemaleWarm, naturalAudiobooks, documentaries
JasperMaleFriendly, clearYouTube, tutorials
LunaFemaleSoft, gentleMeditation, ASMR
BrunoMaleDeep, authoritativeDocumentaries, corporate
RosieFemaleBright, upbeatMarketing, social media
HugoMaleWarm, engagingPodcasts, conversation
KikiFemaleEnergetic, youthfulTikTok, gaming
LeoMaleBold, confidentTrailers, promos

Who Should Use Kitten TTS?

  • Content creators: YouTube voiceovers, podcast narration, TikTok content
  • Developers: Embed TTS in applications, build voice-enabled features
  • Indie game developers: NPC dialogue, game narration without voice actor budgets
  • Educators: Course narration, e-learning voiceovers
  • Businesses: Cost-effective voice generation at scale
  • Privacy-conscious users: 100% offline, data never leaves your machine

The Bottom Line

Kitten TTS represents a new paradigm in text-to-speech: lightweight, efficient, and truly open. While it does not match the absolute quality ceiling of premium services like ElevenLabs, it delivers remarkable results for its tiny size -- and at zero cost. For developers, creators, and businesses who value freedom and efficiency, Kitten TTS is a game-changer.

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