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