Speech-to-text and voice-agent APIs with high accuracy, for developers adding transcription and voice AI to their products.
What it does
AssemblyAI provides speech-to-text and voice AI APIs for developers. Its Universal models transcribe pre-recorded and real-time audio across many languages with speaker diarization, and a Speech Understanding API adds summaries, sentiment and chapters. It also offers voice-agent APIs, PII redaction guardrails and an LLM gateway, priced pay-as-you-go.
Core features
Pre-recorded speech-to-text (99 languages)
Real-time streaming transcription
Speaker diarization
Speech understanding (summaries, sentiment)
Voice Agent API
PII redaction and LLM gateway
Best for
→Transcribing calls and meetings
→Building real-time voice agents
→Adding captions and dictation
→Analyzing conversations at scale
Pricing
Universal-2 STT
$0.15/hr
Universal-3.5 Pro STT
$0.21/hr
Realtime Universal-3.5 Pro
$0.45/hr
Toolspool rankingby monthly traffic
Reviews
Big-picture takes: what it's for and whether it delivers. High-engagement YouTube videos — not sponsored.