Deepgram vs Letterly: Features, Pricing and User Reviews 2026

Deepgram is a comprehensive voice AI platform that provides three main services through easy-to-use APIs. First, it offers Speech-to-Text that converts spoken words into written text with over 90% accuracy, even in noisy environments or with heavy accents. Second, it provides Text-to-Speech that creates natural-sounding voices for apps and voice assistants. Third, it offers Voice Agent APIs that let developers build complete conversational AI systems.

Founded in 2015 and based in San Francisco, Deepgram has become the go-to choice for companies like Spotify, NASA, and Citibank. The platform uses deep learning models specifically trained for real-world audio, not just clean studio recordings. This means it works well for call centers, medical transcription, podcast processing, and live streaming. With response times under 300 milliseconds, it enables real-time conversations that feel natural and immediate.

Letterly is an AI-powered mobile application that converts spoken words into well-structured, polished text. Unlike basic voice-to-text tools that only transcribe what you say, Letterly uses advanced artificial intelligence to understand, organize, and improve your speech automatically. The app offers over 25 different rewrite options, allowing you to transform your voice into various formats like formal emails, social media posts, structured notes, or casual messages.

Available on iOS, Android, web, and macOS platforms, Letterly supports more than 90 languages with automatic detection. You can record up to 90 minutes per session, even when offline, and the app will process everything once you're back online. The tool includes features like screen-off recording, home screen widgets for quick access, and integration capabilities with platforms like Google Docs and Notion through webhooks and Zapier connections.