Deepgram

Production speech-to-text + audio intelligence API.

Speech recognition API with batch and real-time streaming transcription, speaker diarization, and language detection. Its Universal models pair with optional Speech Understanding features (summarization, sentiment, redaction) so a single API can build conversation-intelligence products. Starts with a free credit and pay-as-you-go, per-second billing.

Text-to-speech, voice cloning, and multilingual dubbing.

Hosted speech synthesis at near-human quality — TTS, voice cloning, multilingual dubbing, and conversational voice agents. Default choice when you need a voice that sounds like a person, not a robot.

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.

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.