ElevenLabs

Low-latency streaming text-to-speech for real-time voice.

Streaming-first speech synthesis built around the Sonic family of state-space models. Aims at real-time agent voices where latency between turns is the product. Strong choice for sub-200ms voice loops.

Production speech-to-text. The STT default for many companies.

End-to-end speech recognition platform — real-time streaming, batch transcription, speaker diarization, and language detection. Strong on accented speech, telephony audio, and long-form recordings.

AI text-to-speech that reads any document, PDF, or page aloud.

Speechify is an AI text-to-speech app that turns articles, PDFs, emails, and books into natural-sounding audio with high-definition voices, adjustable speed, and OCR for scanned text. It runs on iOS, Android, web, a browser extension, and desktop, and offers a separate Studio product plus a text-to-speech API for developers.

Empathic Voice Interface — speech-to-speech AI that hears tone.

A voice AI toolkit built around the Empathic Voice Interface (EVI), a speech-to-speech model that infers emotion and prosody from a user's voice and modulates its replies accordingly. Exposed as an API for building expressive voice agents and assistants. From a research lab focused on emotional intelligence in AI.