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Documentation Index

Fetch the complete documentation index at: https://docs.cartesia.ai/llms.txt

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sonic-3 is our streaming TTS model, with high naturalness, accurate transcript following, and industry-leading latency. It provides fine-grained control on volume, speed, and emotion. Key Features:
  • 42 languages supported
  • Volume, speed, and emotion controls, supported through API parameters and SSML tags
  • Laughter through [laughter] tags
For more information, see Volume, Speed, and Emotion.

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Voice selection

Choosing voices that work best for your use case is key to getting the best performance out of Sonic 3.
  • For voice agents: We’ve found stable, realistic voices work better for voice agents than studio, emotive voices. Example American English voices include Katie (ID: f786b574-daa5-4673-aa0c-cbe3e8534c02) and Kiefer (ID: 228fca29-3a0a-435c-8728-5cb483251068).
  • For expressive characters: We’ve tagged our most expressive and emotive voices with the Emotive tag. Example American English voices include Tessa (ID: 6ccbfb76-1fc6-48f7-b71d-91ac6298247b) and Kyle (ID: c961b81c-a935-4c17-bfb3-ba2239de8c2f).
For more information and recommendations, see Choosing a Voice.

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Language support

Sonic-3 supports the following languages:
English (en)French (fr)German (de)Spanish (es)
Portuguese (pt)Chinese (zh)Japanese (ja)Hindi (hi)
Italian (it)Korean (ko)Dutch (nl)Polish (pl)
Russian (ru)Swedish (sv)Turkish (tr)Tagalog (tl)
Bulgarian (bg)Romanian (ro)Arabic (ar)Czech (cs)
Greek (el)Finnish (fi)Croatian (hr)Malay (ms)
Slovak (sk)Danish (da)Tamil (ta)Ukrainian (uk)
Hungarian (hu)Norwegian (no)Vietnamese (vi)Bengali (bn)
Thai (th)Hebrew (he)Georgian (ka)Indonesian (id)
Telugu (te)Gujarati (gu)Kannada (kn)Malayalam (ml)
Marathi (mr)Punjabi (pa)

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Selecting a Model

SnapshotRelease DateLanguagesStatus
sonic-3-2026-01-12January 12, 2026en, de, es, fr, ja, pt, zh, hi, ko, it, nl, pl, ru, sv, tr, tl, bg, ro, ar, cs, el, fi, hr, ms, sk, da, ta, uk, hu, no, vi, bn, th, he, ka, id, te, gu, kn, ml, mr, paStable
sonic-3-2025-10-27October 27, 2025en, de, es, fr, ja, pt, zh, hi, ko, it, nl, pl, ru, sv, tr, tl, bg, ro, ar, cs, el, fi, hr, ms, sk, da, ta, uk, hu, no, vi, bn, th, he, ka, id, te, gu, kn, ml, mr, paStable
the latest stable snapshot of the model When making API calls, you can specify either: 
# Use the base model
# (automatically routes to the latest stable snapshot)
model_id = "sonic-3"

# Or specify a particular snapshot for consistency
model_id = "sonic-3-2026-01-12"

# Try the latest (beta) model (can be 'hot swapped')
model_id = "sonic-3-latest"

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Continuous updates and model snapshots

All models have a base model name (e.g. sonic-3) and a dated snapshot (e.g. sonic-3-2025-10-27). Using the base model will automatically keep you up to date with the most recent stable snapshot of that model. If pinning a specific version is important for your use case, we recommend using the dated version. For testing our latest capabilities, we recommend using sonic-3-latest, which is a non-snapshotted version. sonic-3-latest can be updated with no notice, and not recommended for production. To summarize:
Model IDModel update behaviorRecommended for
sonic-3-YYYY-MM-DDSnapshotted, will never changeCustomers who want to run internal evals before any updates
sonic-3Will be updated to point to the most recent stable snapshotCustomers who want stable releases, but want to be up-to-date with the recent capabilities
sonic-3-latestWill always be updated to our latest beta releasesTesting purposes

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Older Models

For information on sonic-2, sonic-turbo, sonic-multilingual, and sonic, see our page on Older Models.