Published by TonePerfect. Vendor facts checked on 10 September 2026 against public pages; no ratings are invented and no vendor paid to be listed.
At a glance
| API | Languages | Scripted depth | Unscripted | Entry price | Best for |
|---|---|---|---|---|---|
| SpeechSuper | 8 (en, zh, de, fr, es, ko, ja, ru) | Phoneme / word / sentence | Yes (English, IELTS/PTE) | $20/mo minimum, $0.004–0.008 per request | Broad edtech coverage, offline SDK |
| Speechace | 3 (en, fr, es, with regional variants) | Phoneme / syllable / word | Yes (Premium) | $40/mo for 5,000 | English exam preparation |
| Azure AI Speech | 33 locales | Phoneme / syllable / word; prosody on en-US | Yes, streaming | ≈ $1 per audio hour | Breadth, existing Azure stacks, short clips |
| ELSA API | 1 (English) | Word / sentence with stress and intonation | Yes | On request | English consumer apps, exam prediction |
| TonePerfect | 7 (zh, en, fr, es, de, it, pt) | Sound / word / sentence; Mandarin initial / final / tone | No | $10/mo for 2,500 | Multi-language scripted practice, Mandarin, per-unit decisions |
SpeechSuper
The incumbent for language-learning apps. Eight languages, products for words, sentences and paragraphs, semi-scripted and unscripted English (IELTS and PTE style), and an offline iOS/Android SDK licensed per device. Pricing is per request with a $20 monthly minimum and quarterly invoicing; prepaid tiers discount 15–30%. If you need Korean, Japanese or Russian, or on-device scoring, start here. Full comparison →
Speechace
Built around English proficiency: fluency with lexical stress and intonation, IELTS/CEFR/PTE/TOEIC rubric scores on Pro, and spontaneous speech up to two minutes on Premium. Three languages with regional variants (US/UK English, France/Canada French, Spain/Mexico Spanish). Plans bundle requests ($40–125) with $0.008 overage. Best for test-prep products. Full comparison →
Microsoft Azure AI Speech
Pronunciation assessment as a feature of Azure's speech service: 33 locales, accuracy/fluency/completeness scores everywhere, prosody and miscue detail on en-US, unscripted and streaming modes, and per-audio-hour pricing that makes short clips very cheap. The cost is integration: the full feature set lives in the Speech SDK, results need parsing and thresholds are yours to tune. Best for breadth, existing Azure customers and price-sensitive short-clip workloads. Full comparison →
ELSA API
The engine behind a widely used consumer English app, exposed to developers: scripted and unscripted English with stress, intonation and fluency, plus IELTS/TOEFL prediction, trained on a very large non-native English corpus. English only; pricing on request. Best for English-only products that want a recognisable engine. Full comparison →
TonePerfect
Our own API, so judge this paragraph accordingly. Seven languages behind one endpoint with one JSON shape; Mandarin scored as initial, final and tone per syllable with sandhi handled; an explicit per-unit decision so your app knows when to correct and when to stay quiet; word timestamps; audio deleted after scoring; flat plans from $10/month with every dimension included. Scripted speech only, 30 seconds per request, packs labelled experimental while calibration data grows, no free tier. Best for multi-language scripted practice, Mandarin, and teams that want decisions rather than thresholds. Product overview →
How to choose
- List your languages. That alone eliminates most options.
- Decide scripted vs unscripted. Reading practice and drills are scripted; conversation and exam tasks are not.
- Pick the feedback unit. Word colours? Phoneme detail? Mandarin components? Decisions or numbers?
- Run the same 20 recordings through your shortlist. A few natives, a few strong learners, a few beginners with known errors. Check who flags natives and who finds the errors.
- Model the cost at your volume with the pricing comparison.
- Read the data policy. Where does the audio go, and for how long?