Operator: TonePerfect. Contact nik@toneperfect.app for the operator’s legal identity and a business agreement before contracting. These terms apply to the developer API and website at api.toneperfect.app; the learner app at toneperfect.app has its own terms.
1. Your account and keys
You need an account to use the API. Keep your API keys secret: anyone with a key can spend its account's credits. You are responsible for requests made with your keys until you revoke them in the dashboard. Do not put a key in a public web page or a shipped mobile app; call the API from your server (see browser & mobile apps).
2. What you may send
Send recordings of people reading a text you supply, made with their consent (and a parent's or school's consent for children where the law requires it). Do not use the API to identify people, infer their origin or nationality, or for surveillance, and do not send recordings you are not allowed to process. You keep all rights in your audio and text. We use them only to return the assessment you asked for (see privacy): API audio is not stored and is not used to train models.
3. What the results are
Scores are 0–100 engine estimates, and decisions are an engine's estimate of whether to correct a sound. Every language pack is labelled experimental. Results are learning feedback, not a certification, a grade of record or proof of anyone's language level, and you should not use them on their own for decisions about people such as admissions, hiring or exam results. See the methodology.
4. Prices, credits and payment
These terms are generated from the code that runs billing (version 2026-10-07; machine-readable at GET /v1/terms). If something is not listed here, the system cannot do it yet: ask before you rely on it.
| Plan | Price | Credits each month | Extra packs |
|---|---|---|---|
| Starter | $10 / month | 2,500 | — |
| Builder | $50 / month | 15,000 | 10% off packs |
| Scale | $150 / month | 50,000 | 20% off packs |
| Extra pack | List price | Credits |
|---|---|---|
| Starter pack | $10 | 2,500 |
| Builder pack | $40 | 10,000 |
| Scale pack | $100 | 25,000 |
- What a credit buys. One completed assessment of up to 15 seconds of audio; a recording up to 30 seconds uses 2. Not charged: failed assessments, unassessable recordings, rejected requests, engine errors.
- Free credits. 50 once per account, no card, spent before plan credits. When fewer are left than a recording needs, the recording uses what is left. Free credits share a daily capacity limit of 1,500 credits across all accounts.
- Plan credits are granted when a full monthly invoice is paid and roll over while the plan is paid. 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.
- Extra packs are one-time purchases that need an active plan.
- Refunds and disputes. Refunded or disputed payments remove the matching credits; credits already spent become a balance settled by the next purchase.
- Cancellation. Cancel any time from the billing portal; the plan stays paid until the end of the current month.
- What billing supports: card payment of a monthly plan in US dollars, quantity one, where the amount paid equals the plan price. Not supported today: Coupons, promotion codes and discounted invoices (a partly paid invoice grants nothing); Tax added on top of the plan price (the paid total must equal the plan price); Annual or other billing intervals; More than one plan per subscription; Manual, one-off or out-of-band invoices (bespoke invoiced deals are arranged separately, not self-serve); Currencies other than US dollars; Trial periods on a paid plan (use the free credits instead). A school, an invoice or a volume deal is arranged by email (nik@toneperfect.app) before anything is charged.
- Limits: 2 assessments in progress and 60 requests per minute per account; 30 seconds and 10 MB per recording. See limits.
Payments are processed by Stripe. Prices exclude any tax your jurisdiction applies; where tax would be added on top, contact us first, because billing only accepts payments equal to the plan price.
5. Availability and changes
The API runs on a single server today and has no service-level agreement; see status and the capacity notes. We announce changes on the changelog. The compact response schema is versioned; check the changelog before upgrading. The default response may gain fields. We may suspend a key that harms the service or other customers, and will tell you why.
6. Ending
You can stop at any time; cancel the plan in the dashboard. To export or close the account, open Account data in the dashboard and reauthenticate. Resolve any active billing first; financial reconciliation records are retained with a pseudonymous internal account ID. We may close accounts that break these terms.
7. Liability
The service is provided as is. To the extent the law allows, our total liability for any claim is limited to what you paid us in the twelve months before it, and we are not liable for indirect or consequential loss. Nothing here limits liability that cannot be limited by law.
8. Changes to these terms
Changes will be posted here and on the changelog. Questions: nik@toneperfect.app.