Plans
Starter
2,500 credits every month
- All 10 languages
- Unused credits roll over
- Add extra credits anytime
- API keys, playground & usage
Builder
Most popular15,000 credits every month
- All 10 languages
- Unused credits roll over
- 10% off extra credit packs
- API keys, playground & usage
Scale
50,000 credits every month
- All 10 languages
- Unused credits roll over
- 20% off extra credit packs
- API keys, playground & usage
Credits arrive after each successful payment and roll over while you subscribe. Plan changes apply at renewal. Cancel anytime; access continues to the end of the paid period. Unused plan credits stay in the account but can only be spent while a monthly plan is paid; they unlock again when a plan restarts.
What a credit buys
| Recording length | Credits | Starter | Builder | Scale |
|---|---|---|---|---|
| Up to 15 seconds | 1 | $0.0040 | $0.0033 | $0.0030 |
| 15 to 30 seconds | 2 | $0.0080 | $0.0066 | $0.0060 |
| Failed or unassessable | 0 | free | free | free |
Prices per recording are the plan price divided by included credits. A request that fails, times out, or returns assessable: false (silence, wrong sentence, unreadable audio) is not charged. A retried request with the same Idempotency-Key returns the original result and is not charged again.
Extra credit packs
| Pack | Credits | List price | On Builder (10% off) | On Scale (20% off) |
|---|---|---|---|---|
| Starter pack | 2,500 | $10 | $9 | $8 |
| Builder pack | 10,000 | $40 | $36 | $32 |
| Scale pack | 25,000 | $100 | $90 | $80 |
Packs are one-time purchases available to any active subscription and never expire while you subscribe. They are the right tool for a launch spike or a school term; if you need packs every month, the next plan up is cheaper.
Three examples
- A prototype with 50 testers doing ten sentences a day: about 15,000 recordings a month → Builder, $50.
- A classroom product with 2,000 students doing one five-sentence exercise a day on school days: about 200,000 recordings a month → Scale ($150, 50,000 credits) plus six Scale packs at $80 → $630, or $0.0032 per recording.
- A flashcard app where 5% of 10,000 monthly users try the speaking feature five times: 2,500 recordings → Starter, $10.
Limits on every plan
- Up to 120 seconds and 10 MB of audio per request; up to 320 words (600 Mandarin characters) of reference text.
- 2 assessments in progress at once per account, on every plan and on free credits; 60 requests per minute. Queue on your side if you burst higher; an over-limit request returns
429 account_busywithRetry-Afterand is not charged. - The engine gets 90 seconds per assessment on every plan, then the request fails with
503 engine_unavailable, uncharged. Throughapi.toneperfect.appthe website proxy closes a request after 26 seconds; typical assessments take 1–2 seconds (90th percentile 2.2 s). - Scripted speech only: the learner reads the text you send.
Need higher concurrency or an invoice? Email us. For how these prices compare with SpeechSuper, Speechace and Azure, see the pricing comparison; for every free tier and trial on the market, see free pronunciation assessment APIs. Ready to build? The quickstart gets you from key to first score in five minutes.