AssemblyAI

AssemblyAI is a developer-first Voice AI platform for teams that need accurate streaming speech-to-text, speech understanding, guardrails, and a managed Voice Agent API. It is especially relevant for builders who want production-grade voice conversations with turn detection, interruption handling, transcripts, tool calls, and WebSocket-based integration.

Test the agent live

No-signup playground — test transcription, speakers, and summaries on real audio in the browser.

Open the live demo

Quick facts

Platform type

Voice Agent Platform

Inbound calls

Yes

Outbound calls

Yes

Human handoff

Setup difficulty

Technical

Pricing model

$4.50/hour ($0.075/min)

Developer friendly

Yes

Pricing details

AssemblyAI lists Voice Agent API pay-as-you-go pricing at $4.50/hour ($0.075/min), covering the speech-to-speech voice agent pipeline. The pricing page also lists $50 in free credits and custom rate limits/concurrency through contact-sales packaging. Verify with vendor.

Cost estimator

A rough monthly usage cost from your call volume. Always confirm rates with the vendor.

Calls / month

Avg length

min

Rate / min

Estimated monthly

$300

4,000 min / month

$3,600 / year

Same volume across platforms

4,000 min/mo · usage only

AssemblyAI (this)$300
Deepgram$300
Retell AI$760

Comparable platforms priced at your volume using vendor list rates. Verify rates and add any base or provider fees. Compare all platforms at your volume →

Integrations

WebSocket APICustom APITool callingTwilioLLM GatewayGuardrails

Data and permissions

Voice agents may talk to customers, access records, record calls, and trigger external actions.

Can read customer data

Can write or update external systems

Can send messages

Can trigger workflows

Requires API keys

Records calls

Human approval available

Review audio and transcript retention, API key handling, temporary browser tokens, tool-call permissions, guardrails, and data residency needs before production use.