whatmodel.sh / tts / Inworld TTS-1.5 Max
Inworld TTS-1.5 Max
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Inworld TTS-1.5 Max is a closed-weights text-to-speech model from Inworld, released January 2026. Licence: proprietary.
Catalogue identity notes
Vapi registry inworld-tts-15-max, apiModelId tts-1-5-max, vendor ID inworld-tts-1.5-max. Distinct from inworld-tts-1-max (RW-Voice-EQ) and Realtime TTS-2. Rating-only comparison identity; no price, API or run metadata asserted.
Model information sources
Score within the Vapi Humanness · Bradley–Terry rating, 2026-09-25 snapshot comparison set only.
$ how it compares
The text-to-speech models ranked either side of Inworld TTS-1.5 Max, out of 148 with a score, then more from Inworld.
| # | model | score | where | ||
|---|---|---|---|---|---|
| 39 |  IndexTTS (v1) | 62±3 | local | ||
| 40 |  F5-TTS v1 Base | 62±3 | local | ||
| 41 | Inworld TTS-1.5 Max | 62±3 | api $10.00/M chars | ||
| 42 |  ZipVoice | 62±3 | local | ||
| 43 | Ghana TTS 72k | 62±7 | comparison only | ||
| more from Inworld | |||||
| 48 | Inworld Realtime TTS-2 | 61±2 | api $25.00/M chars | ||
see all text-to-speech models · find the ones that fit your machine
$ what it's good at
other tests2 not in a task · 97% of its score
| test | result | vs the others in its run | counts |
|---|---|---|---|
| Vapi Humanness · Bradley–Terry rating, 2026-09-25 snapshot | 1227.3 ✎ | ▁···▁▃··█▄▁▇ beats 12/18 | 64% |
| Vapi Humanness · historical Elo, 2026-06-10 | 1197.3 ✎ | ▃·▃▃▃·▃██▃·▃ beats 5/12 | 33% |
$ where to run it
Through an API
api · fal.ai · $10.00/M chars · fal.ai ↗ · price sourceUSD per 1M input characters: fal prices its 'Text to Speech Endpoint for Inworld's TTS-1.5 Max' (fal-ai/inworld-tts) at $0.01 per 1000 characters (x1000; endpoint billing record: billing_unit 1000 characters, price 0.01). Inworld's own pricing page lists only TTS-2 models, and Inworld's docs mark inworld-tts-1.5-max as deprecated (not recommended for new projects) but not discontinued. Product: fal text-to-speech endpoint. API model: fal-ai/inworld-tts (Inworld TTS-1.5 Max). Settings: standard. Price basis: published list rate, per-1K to per-1M scaling only. Exclusions: DeepInfra lists inworld-ai/realtime-tts-1.5-max (its replacement id for inworld-tts-1.5-max) at $50.00/1M characters. Currency: USD. fal.ai model page, observed 2026-09-25.
$ how the score was worked out · The Humanness Index by Vapi ·… 64%, The Humanness Index by Vapi ·… 33%
Each result implies a score on its own, after adjusting for how hard its test is and who ran it. The score is their weighted average, with a small pull toward the middle for thinly tested models. Each test's weight is its counts column above; here it's added up by who ran the tests. How it works
| source | results | share of the score |
|---|---|---|
 The Humanness Index by Vapi · September 2026 public standings | 1 | 64% |
| The Humanness Index by Vapi · June 2026 production export | 1 | 33% |
| prior · pull toward the middle | 3% | |
| weighted average | = 61.9 |
$ improve this page
Use a short GitHub form or edit the data through a pull request. Every number needs a source; here's which ones we can use.
data updated · sources and licences · json