Cartesia Sonic
Cartesia's Sonic TTS — state-space-model-based voice generation, lowest published TTS latency (~40ms). Cartesia raised $64M Series A Q1 2025 (Index + Lightspeed); founded by Mamba authors. Agent platform layer ('Cartesia Line') wraps Sonic with telephony + LLM.
Active · Verified 2026-10-26 · fresh as of 2026-10-26 · 47 cited facts, 2 with a third-party source · 1 recorded change · Suggest a correction
At a glance
- Type
- Real-time TTS + voice-agent platform (Cartesia) vendor fix
- Tier
- T1
- Section
- Voice agent platforms
- Created
- 2024 (founded) vendor fix
- Latest release
- Sonic-3.6 (current model; release date not stated) vendor fix
- License
- not applicable — not OSS fix
- GitHub
- github.com/cartesia-ai (SDKs) repo fix
- Pricing
- Free (20K credits/mo); Pro $5/mo; Startup $49/mo; Scale $299/mo; Enterprise custom; managed voice agents $0.06/min vendor fix
- Funding
- $64M Series A Q1-2025 (Index + Lightspeed) third-party fix
- Freshness
- 2026-10-26 fix
- Layer
- agent-infra repo fix
- Licensing
- commercial vendor fix
- Accelerator
- aws-genai-accelerator-2024 third-party fix
- SDK languages
- python, rest, typescript vendor fix
- Protocols
- mcp-server vendor fix
- Compliance
- gdpr, hipaa, pci-dss, soc2-type2 vendor fix
When to use
Optimised for: Lowest-latency TTS substrate for voice agents
Anti-fit: TTS-led platform — not turnkey for full call orchestration (use with Vapi/Pipecat/LiveKit)
Pros & cons
Pros
Lowest-latency TTS in market; Mamba-author founders; $64M Series A; SOC 2.
Cons
TTS-only at platform layer — needs orchestrator; SSM voice quality polarising vs Eleven.
Claims & capabilities
Sonic TTS ~40ms time-to-first-byte; SSM architecture (Mamba lineage); $64M Series A
Technical surface
- API surface
- REST + WebSocket APIs + Python/JS SDKs
- Backend storage
- Stateless API; caller manages state
- Deployment
- Both (self-hosted + managed cloud) — managed API; on-prem (incl. air-gapped), customer VPC and OEM under enterprise contract
- Embedding model
- not applicable — not a memory product
- Multi-tenancy
- Multi-tenant Cloud
- MCP
- yes — official Cartesia MCP server (cartesia-ai/cartesia-mcp)
- A2A
- searched not found
- OpenTelemetry
- searched not found
Compare Cartesia Sonic with…
Alternatives to Cartesia Sonic → live options ranked by shared design, licence, hosting and MCP support
Similar systems
Other voice agent platforms in the catalog, ranked by inbound references.
- LiveKit Agents T1
LiveKit Agents — agent framework built on LiveKit's open-source WebRTC media server. LiveKit raised $45M Series B Sep-2024 ($300M val). Powers OpenAI Realtime API's WebRTC transport (LiveKit is the substrate OpenAI chose). Agents framework formally launched 2024.
- ElevenLabs Conversational AI (now ElevenAgents) T1
ElevenLabs launched Conversational AI Nov-2024 — STT + LLM + their own market-leading TTS in one pipeline. Combines vendor's voice cloning + multilingual TTS strengths with hosted call orchestration. ElevenLabs raised $180M Series C Jan-2025 at $3.3B val. As of 2026-10 ElevenLabs markets the platform as ElevenAgents.
- OpenAI Realtime API T1
OpenAI's Realtime API for native speech-to-speech multimodal interaction with GPT-4o — launched Oct 2024 (DevDay). Skips the STT → LLM → TTS pipeline by passing speech directly to GPT-4o. The platform substrate that Vapi/Retell/Bland integrate as one of their LLM choices.
- Pipecat (Daily) T1
Open-source Python framework for real-time voice + multimodal AI agents, maintained by Daily.co. Pipeline-style architecture (STT → context → LLM → TTS) wired over WebRTC. The OSS substrate that many of the voice platforms build on or compose with.
- Hume EVI T1
Hume's Empathic Voice Interface (EVI) — voice agent platform with vocal-affect understanding, using Hume's proprietary speech-prosody models. Hume will shut down the EVI and TTS APIs on 2026-11-13 (announced in its docs). Hume raised $50M Series B Mar-2024 (EQT).
- Speechmatics Flow T2
Speechmatics (UK; STT leader) launched Flow Q4 2024 — conversational voice-agent platform composed on Speechmatics STT + caller LLM. Speechmatics raised $62M Series B (2022); enterprise + media customers. UK / EU data-residency lead. As of 2026-10 the Flow pages and docs redirect to Agent STT, a speech-to-text API for voice agents (Linden model, from $0.30/hour) used via LiveKit, Pipecat or the API; Flow itself is no longer listed.
Sources (46 cited facts, 2 third-party)
Each fact links to the page it came from; the badge says who published it (how to read sources).
- What it is Real-time TTS + voice-agent platform (Cartesia) vendor
- What it does & what's distinct Cartesia's Sonic TTS — state-space-model-based voice generation, lowest published TTS la… vendor
- Claims / benefits Sonic TTS ~40ms time-to-first-byte; SSM architecture (Mamba lineage); $64M Series A vendor
- Modalities voice (TTS + STT) + text vendor
- Created 2024 (founded) vendor
- Latest release Sonic-3.6 (current model; release date not stated) vendor
- GitHub github.com/cartesia-ai (SDKs) repo
- Mindshare Highly-discussed in TTS / SSM-architecture circles 2024-2025 vendor
- Citations Mamba (parent architecture) widely cited paper
- Funding $64M Series A Q1-2025 (Index + Lightspeed) third-party
- Customers / scale Voice-agent platforms (Vapi / LiveKit integrations) + media customers vendor
- Pricing Free (20K credits/mo); Pro $5/mo; Startup $49/mo; Scale $299/mo; Enterprise custom; mana… vendor
- Compliance SOC 2; HIPAA available vendor
- Data handling US / EU regions; opt-out from training vendor
- Deployment Both (self-hosted + managed cloud) — managed API; on-prem (incl. air-gapped), customer V… vendor
- HQ US (San Francisco) vendor
- Founders / pedigree Karan Goel + Albert Gu (Mamba author) vendor
- Performance Sonic vendor benchmarks: ~40ms TTFB; lowest published TTS latency vendor
- API surface REST + WebSocket APIs + Python/JS SDKs vendor
- Latency p50/p99 ~40ms TTS TTFB vendor
- Backend storage Stateless API; caller manages state vendor
- Multi-tenancy Multi-tenant Cloud vendor
- Encryption TLS + AES-256 vendor
- SSO / RBAC SSO on Enterprise vendor
- Versioning Voice IDs versioned vendor
- Tombstoning User-delete vendor
- Namespace primitives per-API-key / per-org vendor
- Forgetting policy Configurable retention vendor
- MCP support yes — official Cartesia MCP server (cartesia-ai/cartesia-mcp) repo
- Import / export Voice clones exportable per ToS vendor
- Validated verticals voice agents, gaming, media, conversational AI vendor
- Time to running <10min (API key + SDK) vendor
- Anti-fit TTS-led platform — not turnkey for full call orchestration (use with Vapi/Pipecat/LiveKit) vendor
- Optimised for Lowest-latency TTS substrate for voice agents vendor
- Adjacent infrastructure Vapi / LiveKit / Pipecat integrate Sonic; ElevenLabs is direct competitor vendor
- Pros Lowest-latency TTS in market; Mamba-author founders; $64M Series A; SOC 2. vendor
- Cons TTS-only at platform layer — needs orchestrator; SSM voice quality polarising vs Eleven. vendor
- Project & sources cartesia.ai/sonic; docs.cartesia.ai vendor
- adoption-accelerator aws-genai-accelerator-2024 third-party
- architecture-deployment-locus cloud vendor
- licensing-bucket commercial vendor
- positioning-platform-vs-product platform vendor
- taxonomy-three-layer-rollup agent-infra repo
- compliance-certifications gdpr,hipaa,pci-dss,soc2-type2 vendor
- sdk-languages python,rest,typescript vendor
- protocol-support mcp-server vendor
What changed
Changes to this record's lifecycle, licence, release, pricing and hosting facts, from the catalog's git history. Subscribe (Atom)
- 2026-10-26
- Latest release “Sonic 2 (2025)” → “Sonic-3.6 (current model; release date not stated)” source
- Pricing “Per-character TTS pricing; volume tiers” → “Free (20K credits/mo); Pro $5/mo; Startup $49/mo; Scale $299/mo; Enterprise custom; managed voice agents $0.06/min” source
- Deployment “Cloud-managed; private deployments on Enterprise” → “Both (self-hosted + managed cloud) — managed API; on-prem (incl. air-gapped), customer VPC and OEM under enterprise contract” source
- MCP support first recorded as “yes — official Cartesia MCP server (cartesia-ai/cartesia-mcp)” source
Related systems
Referenced by (11)
- Cloudflare AI Gateway integrates with — Cloudflare AI Gateway docs have a Cartesia provider page. (verified 2026-10-29)
- Google Agent Development Kit (ADK) integrates with — ADK integrations catalog has a "Cartesia MCP tool for ADK" page (Generate speech, localize voices, and create audio content). (verified 2026-10-29)
- LiveKit Agents integrates with — LiveKit Agents docs have a Cartesia Sonic model plugin page. (verified 2026-10-29)
- Phidata (now Agno) integrates with — Agno ships a cartesia toolkit (agno.tools.cartesia). (verified 2026-10-29)
- Pipecat (Daily) integrates with — Pipecat docs have a Cartesia Sonic service page. (verified 2026-10-29)
- RULER cites — S2 isInfluential citation
- Test-time training (TTT) cites — S2 isInfluential citation
- Titans (Google) cites — S2 isInfluential citation
- TrueFoundry AI Gateway integrates with — TrueFoundry AI Gateway docs have a Cartesia model-provider page. (verified 2026-10-29)
- Vapi integrates with — Vapi docs list Cartesia Sonic as a provider/integration. (verified 2026-10-29)
- Vercel AI SDK integrates with — AI SDK docs have a Cartesia official AI SDK provider page. (verified 2026-10-29)