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Side-by-side facts to help you choose between voice agents or platforms.
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Voice Agent Platform
AssemblyAI
Voice AI infrastructure and managed Voice Agent API for production real-time voice agents.
AI Receptionist
Synthflow
No-code AI voice agent platform for business call automation, now sold through enterprise contracts.
Highlighted rows differ between these picks
| Attribute | AssemblyAI | Synthflow | Vapi |
|---|---|---|---|
| Platform type | Voice Agent Platform | AI Receptionist | Developer API |
| Pricing | $0.075/min $4.50/hour ($0.075/min) | Enterprise pricing Enterprise contracts from $30,000/year; no self-serve plan | $0.13-$0.33/min $0.05/min hosting + provider costs |
| Test it | Open live demo | (740) 284-8845 | Free trial |
| Calls | Inbound, Outbound | Inbound, Outbound | Inbound, Outbound |
| Human handoff | No | Yes | Yes |
| Setup difficulty | Technical | Easy | Technical |
| Use cases | Customer Support Appointment Scheduling Lead Qualification Healthcare Intake | AI Receptionists Appointment Scheduling Lead Qualification Customer Support | Customer Support Appointment Scheduling Lead Qualification Outbound Calling |
| Useful for |
|
|
|
| Integrations | |||
| Custom API | — | ||
| Twilio | — | ||
| Zapier | — | ||
| WebSocket API | — | — | |
| Tool calling | — | — | |
| LLM Gateway | — | — | |
| Guardrails | — | — | |
| HubSpot | — | — | |
| Calendly | — | — | |
| Google Calendar | — | — | |
| +3 more across these tools — see each profile for the full list. | |||
Platform type
- AssemblyAI
- Voice Agent Platform
- Synthflow
- AI Receptionist
- Vapi
- Developer API
Pricing
- AssemblyAI
$0.075/min
$4.50/hour ($0.075/min)
- Synthflow
Enterprise pricing
Enterprise contracts from $30,000/year; no self-serve plan
- Vapi
$0.13-$0.33/min
$0.05/min hosting + provider costs
Test it
- AssemblyAI
- Open live demo
- Synthflow
- (740) 284-8845
- Vapi
- Free trial
Calls
- AssemblyAI
- Inbound, Outbound
- Synthflow
- Inbound, Outbound
- Vapi
- Inbound, Outbound
Human handoff
- AssemblyAI
- No
- Synthflow
- Yes
- Vapi
- Yes
Setup difficulty
- AssemblyAI
- Technical
- Synthflow
- Easy
- Vapi
- Technical
Use cases
- AssemblyAI
- Customer SupportAppointment SchedulingLead QualificationHealthcare Intake
- Synthflow
- AI ReceptionistsAppointment SchedulingLead QualificationCustomer Support
- Vapi
- Customer SupportAppointment SchedulingLead QualificationOutbound Calling
Useful for
- AssemblyAI
- • Developer teams
- • Real-time voice agents
- • Streaming speech accuracy
- Synthflow
- • No-code setup
- • AI receptionists
- • Appointment workflows
- Vapi
- • Developer teams
- • Custom call workflows
- • Voice AI prototypes
Integrations
| AssemblyAI | Synthflow | Vapi | |
|---|---|---|---|
| Custom API | — | ||
| Twilio | — | ||
| Zapier | — | ||
| WebSocket API | — | — | |
| Tool calling | — | — | |
| LLM Gateway | — | — | |
| Guardrails | — | — | |
| HubSpot | — | — | |
| Calendly | — | — | |
| Google Calendar | — | — |
+3 more across these tools — see each profile for the full list.
What would these cost to run?
Enter your call volume once and see AssemblyAI, Synthflow and Vapi priced at the same usage, ranked alongside every other platform.