Cartesia Sonic vs iSpeech
Cartesia Sonic
cartesia.aiiSpeech
ispeech.orgSide by side
| Figure | Cartesia Sonic | iSpeech |
|---|---|---|
| Price from | $5/mo | $0.25/mo |
| Free plan | Yes | Yes |
| Free trial | — | Yes |
| Open source | — | Yes |
| Web | Yes | Yes |
| Windows | — | Yes |
| macOS | — | Yes |
| Linux | — | Yes |
| iOS | — | Yes |
| Android | — | Yes |
| API | Yes | Yes |
| Plans published | 6 | 15 |
| Spec score · Text-to-Speech Software | 8.7 (#28) | 9.2 (#6) |
| Spec score · Text-to-speech tools | 8.7 (#33) | 9.2 (#11) |
| API access | Yes | API access requires an API key, with mobile development, mobile production, and web/general production key types. |
| Commercial use | Yes | Yes |
| Free plan | Yes | Yes |
| Headquarters | San Francisco, California, United States | The company lists Newark, New Jersey as headquarters and San Francisco as an additional office. |
| Languages | Sonic supports 44 languages. | The homepage says the Speech API supports text-to-speech and speech recognition in more than 30 languages. |
| Platforms | web,api | web,ios,android,api |
| Product | Sonic is a text-to-speech model for real-time voice applications. | iSpeech provides text-to-speech and automated speech recognition services through APIs, SDKs, and online tools. |
| Security | Cartesia lists HIPAA compliance, SOC 2 Type 2, GDPR, and PCI on the Sonic page. | The privacy policy says iSpeech uses commercially reasonable physical, managerial, and technical safeguards, while stating it cannot warrant the security of transmitted information. |
| Paid from | 5 | 2.95 |
| Support | Cartesia's documentation directs users to Discord to chat with the Cartesia team and community for help. | The developer pricing page lists priority technical support with purchases; the API guide directs support requests to [email protected]. |
Plans
Cartesia Sonic
- FreeFree
- Pro$5 a month
- Startup$49 a month
- Scale$299 a month
- FreeFree
- EnterprisePriced on request
iSpeech
- Plus$2.95 a month
- Premium$3.95 a month
- Pay Per Use$50 a month
- Pay Per Install$0.25 a month
- BasicFree
- HackerFree
- Plus$2.95 a month
- Premium$3.95 a month
- Junior$29 a month
- Pay-per-use 2,000 credits$50, paid once
In their own words
Cartesia Sonic
Cartesia Sonic is a text-to-speech model for real-time voice applications, available through the web and an API. It has sub-90ms latency and supports 44 languages. Sonic can interpret emotional subtext and add non-verbal expressions such as laughter to transcripts. Its localization feature carries emotion, tone, and speaker identity into another language, while custom pronunciation dictionaries let users set how proper nouns and domain terms are spoken. For voice agents, Managed Agents combine Ink-2 speech-to-text, a selected LLM, and Sonic-3.6 text-to-speech, with turn-taking and interruption handling. Phone connectivity can use Cartesia-provisioned numbers, imported Twilio numbers, or a carrier over SIP. Cartesia lists HIPAA compliance, SOC 2 Type 2, GDPR, and PCI. It says Sonic can be deployed on-premise, in a customer VPC on AWS, GCP, or Azure, or through OEM licensing. A free plan includes 20K credits per month and two concurrent text-to-speech requests. Paid plans start at $5/mo; higher tiers raise credit allowances and list capabilities including organizations and priority support.
iSpeech
iSpeech provides text-to-speech and automated speech recognition through APIs, SDKs, and online tools. Its speech API can synthesize audio with multiple voices, formats, bitrates, frequencies, and playback speeds, and supports MathML and SSML. The API can also transcribe submitted audio across multiple languages and recognition models; iSpeech says custom models can be created. The homepage lists support for more than 30 languages. Audio downloads are available in AIFF, MP3, OGG, WMA, FLAC, WAV, A-law, μ-law, VOX, and MP4 formats. Listed access includes Android, iOS, Linux, macOS, web, Windows, API, and extension. The Basic plan is free for personal use, and commercial use is listed as available. Plus costs $2.95 a month, billed monthly, and includes 30-minute recordings, approximately 4,167 words. Premium costs $3.95 a month, billed monthly, with 12-hour recordings, approximately 100,000 words. Pay Per Use costs $50 a month for dynamic TTS usage only and includes 2,000 credits. Pay Per Install costs $0.25 a month and has a 10,000-install minimum.