Compare realtime APIs
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| Neuphonic API Neuphonic | Resemble AI TTS (Chatterbox models) Resemble AI | Smallest.ai Waves Lightning v3.1 Smallest AI | |
|---|---|---|---|
| Category | Text-to-speech | Text-to-speech | Text-to-speech |
| Status | GA | GA | GA |
| Est. per minute | n/a | n/a | n/a |
| How that was worked out | Pricing not published | Not verifiable from official pages; third-party sources range from ~$0.03 to ~$0.36 per minute | Official per-character rate not retrievable; third-party figures imply ~$0.013-0.023/min |
| Pricing model | subscription | per-minute | per-character |
| Free tier | Playground available; API free tier not verified | Flex pay-as-you-go credits never expire (detection page); TTS free tier not verified | $10 free credits (platform) |
| Connects by | WebSocket, SSE | WebSocket, HTTP chunked | WebSocket, SSE, HTTP chunked |
| Audio in | Text with inline <pause> and <phoneme> tags | Text or SSML, max 3,000 characters excluding tags | Text (pronunciation dictionaries on WebSocket) |
| Audio out | Not verified | wav/pcm etc.; example uses wav 32 kHz PCM_32; JSON (base64) or binary frames | pcm default; 8000/16000/24000/44100 Hz |
| Languages | 37 (homepage playground); NeuTTS-2M spec lists 7 | English for Turbo; Chatterbox Multilingual covers 23+ languages | 12 with trained voices; 20 accepted codes plus auto |
| Latency (vendor claim) | Third-party listings cite a vendor sub-25 ms figure; Vapi Humanness Index measured ~763 ms for the model it tested. | Vendor (Chatterbox README): hosted service sub-200 ms. | Vendor: 200 ms TTFB at 40 concurrent requests in-region. Vapi measured 420 ms median including network. |
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| Compliance | Not verified. | Enterprise on-prem available; SOC 2 documentation mentioned for enterprise on the pricing page. | Zero data retention on enterprise plans. |
| Self-hostable | Yes | Yes | No |
| Last checked | 2026-10-10 | 2026-10-10 | 2026-10-10 |
| Key numbers and features | |||
| $/1M chars | - | - | - |
| Free tier | - | - | Yes |
| Free credit $ | - | - | $10 |
| Free tier commercial | - | - | - |
| Voices | - | - | 217 |
| Cloning | Yes | Yes | Yes |
| Instant clone | - | - | - |
| Text stream in | - | No | Yes |
| Timestamps | - | Yes | Yes |
| Emotion | - | - | - |
| SSML | - | Yes | - |
| 8 kHz phone | - | - | - |
| Latency ms | 25 | 200 | 200 |
| Languages | 37 | 1 | 12 |
| Max session min | - | - | - |
| Concurrency | - | 20 | 1 |
| WebRTC | No | No | No |
| WebSocket | Yes | Yes | Yes |
| gRPC | No | No | No |
| HIPAA | - | - | - |
| SOC 2 | - | Yes | - |
| EU data | - | - | No |
| Self-host | Yes | Yes | No |
| Open weights | Yes | Yes | No |
| High warnings | 0 | 2 | 1 |