Overview
Synthflow is a Berlin-based, no-code platform for building enterprise voice AI agents that automate inbound and outbound phone calls. Founded in 2023 and backed by a $30M Series A led by Accel, it targets businesses that want production phone agents without hiring engineers. The core product is a visual Flow Designer where you drag and drop nodes for branching logic, real-time booking, human handoff, and post-call actions, then connect it to your CRM. Under the hood it orchestrates best-of-breed providers — ElevenLabs for voice synthesis, Deepgram for transcription, and your chosen LLM — so you bring your own keys rather than being locked to one stack. In our evaluation the differentiator is the agency angle: native white-label with custom domain, subaccounts, and Stripe rebilling lets a shop resell voice agents under its own brand, and the BELL framework (Build, Evaluate, Launch, Learn) adds a pre-launch test center that simulates calls before go-live. It claims sub-100ms in-house telephony and 99.99% uptime, supports 40+ languages, and carries SOC2/HIPAA/GDPR certifications. The weaker spots are pricing clarity — the public page now leans pay-as-you-go plus a ~$30k/yr enterprise floor — and turn latency, which third-party benchmarks place around 3 seconds, behind developer-first platforms.
Key Features
- No-code Flow Designer — drag-and-drop branching, jump-to routing, and human-transfer nodes; no engineering required.
- Inbound and outbound automation — appointment booking, lead qualification, surveys, and SMS follow-ups.
- Bring-your-own providers — connect ElevenLabs, Deepgram, and your own LLM via API keys.
- Agency white-label — custom domain, subaccounts, and Stripe rebilling to resell under your brand.
- BELL deployment framework — a pre-launch test center simulates hundreds of call scenarios before production.
- 200+ integrations — HubSpot, GoHighLevel, Salesforce, Calendly, Zapier, and Make.
- Compliance posture — SOC2, HIPAA, GDPR, and PCI DSS for regulated industries.
Pricing
| Plan | Price | What’s included | Notes |
|---|---|---|---|
| Free | $0 | Build and test agents, templates, visual designer | No live calls included |
| Starter | $29 / mo | Live calls, pay-as-you-go minutes, 1 assistant | 50 mins, 5 concurrent calls |
| Pro | $450 / mo | Multiple agents, CRM sync, voicemail detection | 2,000 mins, then ~$0.13/min |
| Growth | $900 / mo | More workspaces, assistants, rebilling | 4,000 mins, then ~$0.12/min |
| Agency | $1,400 / mo | White-label, unlimited subaccounts | 6,000 mins, then ~$0.12/min |
| Enterprise | From ~$30k / yr | Volume pricing, SIP trunking, SLA | Custom integrations, compliance |
In our evaluation the Free tier is enough to design and test a flow, but live calling starts at Starter. Note the official page has moved toward pay-as-you-go (~$0.15-0.37/min all-in) plus Enterprise, so confirm current rates before committing.
Comparison
vs. ElevenLabs: ElevenLabs is the voice-quality and cloning leader, excellent as the speech engine inside a pipeline, but it is not a no-code call-agent platform. Synthflow wraps that capability (and others) into a deployable phone-agent product, so the two are complementary rather than competing.
vs. Vapi: Vapi is the developer-first choice — fast, programmable, and latency-optimized for engineers building custom call flows. Synthflow wins on ease of setup and white-label for non-technical teams; Vapi wins on control and speed.
vs. Retell: Retell sits between the two — solid APIs with some no-code convenience. Synthflow’s visual builder and agency toolkit are broader, while Retell appeals to teams wanting a lean, API-centric layer.