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AssemblyAI Voice Agent API vs Vapi

Pricing last verified from each vendor's own site.

Verdict

AssemblyAI bundles the whole agent stack into $4.50/hr (about $0.075/min), billed per second. Vapi is an orchestration platform that bills per minute with transcriber, model and voice costs listed separately, plus $5 free credits.

Factual summary

This is a factual comparison drawn from vendor sites, not a recommendation. Which fits depends on your channels, volume and budget.

AssemblyAI Voice Agent APIVapi
SummarySpeech-to-text API provider with an all-inclusive Voice Agent API for building AI phone agents.Developer platform for building voice AI agents.
Starting priceSee vendorSee vendor
Pricing detailsVoice Agent API $4.50/hr (about $0.075/min) all-in: real-time speech-to-text, turn detection, its Voice Agent LLM, text-to-speech and hosting, billed per second; speech-to-text from $0.15/hr; free tier (no card) includes up to 185 hours of pre-recorded and 333 hours of streaming transcription; volume pricing via salesUsage-based per minute, with transcriber, model and voice costs listed separately; $5 free credits; optional support packages: Core $29/mo, Pro $999/mo minimum
Modelusageusage
Free trial——
Free planYes—
Channelsphonephone
Last verified2026-10-272026-10-28

FAQ

What is the difference between AssemblyAI Voice Agent API and Vapi?

AssemblyAI bundles the whole agent stack into $4.50/hr (about $0.075/min), billed per second. Vapi is an orchestration platform that bills per minute with transcriber, model and voice costs listed separately, plus $5 free credits.

Which is cheaper, AssemblyAI Voice Agent API or Vapi?

We can't compare entry prices directly. AssemblyAI Voice Agent API: Voice Agent API $4.50/hr (about $0.075/min) all-in: real-time speech-to-text, turn detection, its Voice Agent LLM, text-to-speech and hosting, billed per second; speech-to-text from $0.15/hr; free tier (no card) includes up to 185 hours of pre-recorded and 333 hours of streaming transcription; volume pricing via sales. Vapi: Usage-based per minute, with transcriber, model and voice costs listed separately; $5 free credits; optional support packages: Core $29/mo, Pro $999/mo minimum.

When should I choose AssemblyAI Voice Agent API over Vapi?

Consider AssemblyAI Voice Agent API if: You want a single predictable per-minute price. Consider Vapi if: You want to mix providers and use Vapi's tooling.

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