Catalog Systems Voice agent platforms Synthflow

Synthflow

https://synthflow.ai/

No-code voice-AI platform — drag-and-drop call-flow builder targeted at non-developers. Berlin-based; raised $7.4M Series A Sep-2024 (Singular). Distinguishes itself from Vapi/Retell with visual call-flow builder rather than code-first SDK.

Active · Verified 2026-10-27 · fresh as of 2026-10-27 · 42 cited facts, 0 with a third-party source · 1 recorded change · Suggest a correction

At a glance

Type
No-code voice-agent builder (telephony) vendor fix
Tier
T2
Section
Voice agent platforms
Created
2023 (founded) vendor fix
Latest release
not applicable — not OSS fix
License
not applicable — not OSS fix
GitHub
not applicable — no GitHub repo fix
Pricing
Enterprise contracts from $30,000/yr, scoped by call volume, concurrency, telephony and integrations vendor fix
Funding
$20M Series A (2025-06-25) led by Accel with Atlantic Labs and Singular; $30M total vendor fix
Freshness
2026-10-27 fix
Layer
agent-infra repo fix
Licensing
commercial vendor fix
Deployment locus
cloud vendor fix
Platform vs product
platform vendor fix
SDK languages
rest vendor fix
Protocols
mcp-client, mcp-server vendor fix
Compliance
gdpr, hipaa, pci-dss vendor fix

When to use

Optimised for: SMB voice agents via visual builder; EU residency

Anti-fit: No-code-first → less flexible than Vapi/Retell for complex programmatic use cases

Pros & cons

Pros

No-code builder; EU data residency; SOC 2 + GDPR; SMB-friendly pricing.

Cons

Smaller / EU-centric; less programmatic than Vapi; vendor-pipeline (not vertically integrated).

Claims & capabilities

$7.4M Series A Sep-2024 (Singular); no-code visual builder; EU residency option

Technical surface

API surface
REST API + dashboard + Zapier integration
Backend storage
Call state in Synthflow-managed DB
Deployment
Cloud-managed (EU + US regions)
Embedding model
not applicable — not a memory product
Multi-tenancy
Multi-tenant cloud
MCP
yes — Synthflow MCP server for managing agents, calls and knowledge bases from MCP clients
A2A
searched not found
OpenTelemetry
searched not found

Alternatives to Synthflow → live options ranked by shared design, licence, hosting and MCP support

Similar systems

Other voice agent platforms in the catalog, ranked by inbound references.

  • Cartesia Sonic T1

    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.

  • 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).

Sources (41 cited facts, 0 third-party)

Each fact links to the page it came from; the badge says who published it (how to read sources).

What changed

Changes to this record's lifecycle, licence, release, pricing and hosting facts, from the catalog's git history. Subscribe (Atom)

  1. 2026-10-27
    • Pricing “Tiered: Starter $29/mo + per-minute; Pro $450/mo” → “Enterprise contracts from $30,000/yr, scoped by call volume, concurrency, telephony and integrations” source
    • Funding / ownership “$7.4M Series A Sep-2024 (Singular lead)” → “$20M Series A (2025-06-25) led by Accel with Atlantic Labs and Singular; $30M total” source
    • MCP support first recorded as “yes — Synthflow MCP server for managing agents, calls and knowledge bases from MCP clients” source
    #273

Related systems

References (2)