AssemblyAI

AssemblyAI is an API-first Speech AI platform for developers and product teams that need accurate transcription and structured insights from voice data in applications like voice agents, conversation intelligence, and analytics.

Key capabilities include:

• Speech-to-text transcription with support for 99+ languages, automatic language detection, and custom vocabulary, plus options for real-time streaming transcription.
• Speaker diarization and dual-channel detection to separate participants in calls, meetings, and interviews.
• Speech understanding models for extracting insights such as sentiment analysis, topic detection, and entity detection from audio.
• Safety and compliance features including PII redaction and profanity filtering for content guardrails.

Pricing: Usage-based, per-second API pricing with custom enterprise options.

Notable for its large-scale production usage (processing over 40 TB of audio daily and 600M+ inference calls per month) and its developer-oriented tooling (documentation, API reference, playground), plus GDPR and SOC 2 compliance for organizations handling sensitive voice data.