Video example · IndexTTS 2
Expressive speech in a real scene
Watch an IndexTTS 2 example and hear how expressive, controllable speech is generated.
IndexTTS · AI Text to Speech · Zero-Shot Voice Cloning
IndexTTS – AI Text to Speech and Voice Cloning
IndexTTS brings natural AI speech, zero-shot voice cloning, and controllable text to speech into one modern voice creation experience — for narration, expressive speech, and multilingual AI voice generation.
Online demo · Registered
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Spoken text · English · Sad
“I feel like I'm lost in the darkness and can't find a way out anymore.”
INDEXTTS / 02 — Official media examples
See and hear IndexTTS in action
Play the official video and audio directly beside their descriptions — no separate gallery or hidden player.
IndexTTS 2 English speech
Official English audio sample
“The equipment needed to do this includes rock saws and polishers.”
English audio example · IndexTTS 2
Listen to English speech generation
Play the official English sample directly to hear natural pronunciation and controlled speech duration.
INDEXTTS / 03 — What is IndexTTS
What is IndexTTS?
Key idea
IndexTTS is an online AI text-to-speech platform. Upload a short reference recording, type your script, and generate natural, expressive speech in your browser — with zero-shot voice cloning, emotion control, and multilingual support.
The system produces natural synthetic speech that communicates meaning: rhythm follows the text, pronunciation stays understandable, a cloned speaker remains recognizable, and emotion and pacing fit the content.
Under the hood, IndexTTS is open source: code and model weights are released under the project's open-source license and are free for commercial projects — see the official repository for the LICENSE details.
That combination makes IndexTTS useful for creators who need more flexibility than ordinary text-to-speech software, whether for narration, expressive dialogue, or multilingual content.
Zero-shot speech synthesis Pronunciation control Speaker conditioning Multilingual family Open source & free
A few seconds of reference audio is all the model needs to reproduce a speaker.
INDEXTTS / 04 — Core capabilities
From text to natural AI speech and zero-shot voice cloning
IndexTTS capability
From Text to Natural AI Speech
Key idea
At the center of IndexTTS is text-to-speech generation. Written content becomes synthesized audio that can be used across media, creative, educational, and technical projects.
The original IndexTTS system was introduced as an industrial-level controllable and efficient zero-shot TTS system. Its research combines character and Pinyin modeling for Chinese pronunciation control and improves speaker conditioning and audio generation to strengthen voice-cloning stability and naturalness.
For everyday users, this means the IndexTTS text to speech experience can go beyond choosing a voice and pressing a button. The technology is designed around a richer question: how can generated speech preserve the qualities people actually notice when listening?
Those qualities include speaker identity, pronunciation, sentence flow, clarity, expression, and consistency.
IndexTTS capability
Zero-Shot Voice Cloning with IndexTTS
Key idea
Voice cloning is one of the central capabilities of IndexTTS. The official project describes the system as capable of cloning a voice from a single reference audio clip.
Instead of training a completely separate model for every new speaker, an IndexTTS voice cloning workflow can use reference speech to guide the characteristics of generated audio.
This opens up possibilities for authorized personal narration, recurring creative characters, brand voices, accessibility projects, prototypes, and content where the same speaker needs to appear across many pieces of audio.
The reference recording remains important. Clear speech provides a stronger representation of the target speaker than noisy or heavily processed audio. Responsible use is equally important: reference voices should only be used when you own the voice or have appropriate permission.
When used appropriately, IndexTTS can make consistent AI voice production considerably more flexible.
INDEXTTS / 05 — The model family
The IndexTTS Model Family
IndexTTS is more than a single model — the official project maintains IndexTTS, IndexTTS 2, and IndexTTS 2.5.
Original
IndexTTS
The original model establishes the core zero-shot speech and voice-cloning foundation.
Explore IndexTTSEmotion & duration
IndexTTS 2
Moves toward highly expressive emotional speech and controllable speech duration, separating speaker identity from emotional expression.
Explore IndexTTS 2Multilingual
IndexTTS 2.5
Extends the family with broader multilingual generation, faster inference, pronunciation control, and adjustable speaking speed — supporting Chinese, English, Japanese, Spanish, and Arabic.
Explore IndexTTS 2.5INDEXTTS / 06 — Built around control
A Voice Generator Built Around Control
Key idea
A useful IndexTTS AI voice generator should give creators room to make decisions instead of forcing every project through the same output style.
Pronunciation is one example. A technically correct sentence can still sound wrong when a name, polyphonic character, acronym, or specialized term is pronounced incorrectly.
The original IndexTTS research specifically addresses controllable Chinese pronunciation through character-and-Pinyin modeling. Later generations expand those ideas further.
Speaker identity is another form of control. A reference voice can provide a recognizable vocal foundation.
Expression adds another dimension. Newer IndexTTS models can separate emotional delivery from speaker identity, making it possible to explore different performances without treating emotion and timbre as the same thing.
Together, these capabilities make IndexTTS relevant to people who care not only about generating speech, but about shaping how that speech is heard.
Pronunciation
Character-and-Pinyin modeling for correct Chinese; phoneme guidance in English and Japanese.
Speaker identity
A reference voice provides a recognizable vocal foundation for every generation.
Emotional delivery
Emotion separated from timbre — explore different performances independently.
Pacing & duration
Duration and speaking-speed controls shape how speech is heard.
INDEXTTS / 07 — Use cases
Content creation and creative workflows
IndexTTS capability
IndexTTS for Modern Content Creation
Key idea
AI-generated audio can support many forms of digital content, but the purpose of the audio changes from project to project.
A video creator may need narration that fits the tone of a scene. A marketer may need multiple versions of a voiceover as copy changes. A developer may want speech for a prototype. An educator may need clear spoken lessons. A storyteller may want characters with consistent identities.
IndexTTS provides a common speech-generation foundation for these very different workflows.
Instead of rebuilding a recording process every time the script changes, creators can use IndexTTS to experiment with new wording, alternative lines, different delivery styles, and new audio directions.
This makes IndexTTS online especially attractive for users who want AI voice generation without turning every revision into a traditional recording session.
IndexTTS capability
IndexTTS for Creators
Key idea
For creators, speed is useful, but flexibility is often more important.
A script can change after a video edit. A product feature can be renamed. A sentence may need to be shortened. A character's emotional direction may change during production.
With IndexTTS, speech generation can become part of the creative iteration process.
Instead of treating narration as a final step that cannot easily change, an IndexTTS AI voice workflow makes audio something creators can test, compare, revise, and improve alongside the rest of the project.
That can be valuable for YouTube content, short videos, presentations, demonstrations, storytelling, digital characters, learning materials, and experimental media.
INDEXTTS / 08 — Developers & AI projects
IndexTTS for Developers and AI Projects
Key idea
Developers can also use IndexTTS as part of larger AI and media systems.
The official project provides model checkpoints, Python inference examples, a local WebUI, and deployment-oriented resources. The current repository also documents vLLM-based production deployment for IndexTTS 2.5.
This means IndexTTS can be explored not only as a standalone text-to-speech model but also as a speech component in broader applications.
Possible directions include interactive characters, virtual assistants, media generation workflows, narration systems, prototypes, learning applications, and other products where generated speech is needed.
The exact architecture of the surrounding application can vary, but IndexTTS provides a speech layer designed around controllable zero-shot synthesis.
INDEXTTS / 09 — Choose a model
Choose the Right IndexTTS Model
Key idea
The best IndexTTS version depends on what you want to accomplish.
If your interest is the foundation of the system and controllable zero-shot TTS, the original IndexTTS provides the starting point.
If your priority is expressive emotional speech and understanding how emotion can be controlled independently from speaker identity, IndexTTS 2 deserves closer attention. Its research also explores precise duration control for timing-sensitive speech synthesis.
If multilingual generation, faster inference, speaking-speed control, or expanded pronunciation features matter most, IndexTTS 2.5 is the current generation to explore.
By separating these models into dedicated pages, you can learn about each IndexTTS generation without mixing every feature into a single explanation.
INDEXTTS / 10 — Why IndexTTS
Why IndexTTS Matters for AI Speech
Key idea
AI speech is moving from simple narration toward controllable generation.
Users increasingly want more than a synthetic voice that reads text correctly. They want speech that can maintain identity, communicate emotion, pronounce difficult content, work across languages, and fit real creative workflows.
The evolution of IndexTTS reflects that direction.
The original system emphasizes controllable pronunciation and stable zero-shot voice cloning. IndexTTS 2 expands expressive and duration-related capabilities. IndexTTS 2.5 extends multilingual coverage, performance, speed control, and pronunciation control.
Together, the IndexTTS model family provides a useful way to explore how modern AI speech can become more controllable without losing naturalness.
IndexTTSGen 1
Foundation: Controllable pronunciation and stable zero-shot voice cloning.
IndexTTS 2Gen 2
Emotion & duration: Expressive emotional speech with timbre–emotion disentanglement.
IndexTTS 2.5Gen 3
Multilingual & fast: Five languages, speed control, pronunciation control, streaming inference.
INDEXTTS / 11 — Pricing
Choose the credit pack that fits your workflow
One-time purchases with no subscription — new accounts receive free credits, and purchased credits never expire.
Starter
A quick creative test run
$9.90one-time
1,500 credits
About 25 minutes of generated speech
Best forQuick tests and first projects
- 1,500 credits included
- $0.0066 per credit
- One-time payment · no subscription
- Purchased credits never expire
- Natural expressive text to speech
- Zero-shot voice cloning from 3–10s reference audio
- Emotion, speed & duration control
- Multilingual + cross-lingual voice transfer
Most popular
Creator
More room to explore ideas
$29.90one-time
5,000 credits
About 83 minutes of generated speech
Best forCreators and recurring content
- 5,000 credits included
- $0.0060 per credit
- One-time payment · no subscription
- Purchased credits never expire
- Streaming low-latency synthesis
- Advanced emotion & duration control
- Full commercial license for projects
- Faster priority cloud generation
Studio
The best value for production
$49.90one-time
12,000 credits
About 200 minutes of generated speech
Best forStudios and production teams
- 12,000 credits included
- $0.0042 per credit — lowest unit price
- One-time payment · no subscription
- Purchased credits never expire
- Batch generation & API workflows
- Voice asset management for teams
- Commercial license + priority support
- Ideal for dubbing, audiobooks & podcasts
Payments are processed securely by Stripe · One-time purchases · No recurring billing · See full pricing details
INDEXTTS / 12 — FAQ
IndexTTS FAQ
IndexTTS is an online AI text-to-speech platform: upload a short reference recording, type your script, and generate natural, expressive speech in your browser — with zero-shot voice cloning, emotion control, and multilingual support. The project is also open source, with code and model weights free for commercial use.
INDEXTTS / 13 — Explore
Explore IndexTTS
IndexTTS provides a path from basic text-to-speech generation toward more expressive, controllable, and multilingual AI voice creation.
Explore the original IndexTTS technology to understand its zero-shot voice-cloning foundation. Discover IndexTTS 2 when emotional expression and speaker identity matter. Explore IndexTTS 2.5 for the latest multilingual, pronunciation, performance, and speaking-speed improvements.
Whether you are creating content, developing an AI application, experimenting with voice technology, or simply looking for a more flexible way to generate spoken audio, IndexTTS gives you a growing family of models designed around natural and controllable speech.
References: GitHub · index-tts/index-tts · Official IndexTTS page