AssemblyAI Voice Agent API vs OpenAI Realtime API: Which should you use?

The text provides a detailed comparison between AssemblyAI's Voice Agent API and OpenAI's Realtime API, highlighting key differences in architecture, pricing, speech accuracy, and developer experience. AssemblyAI's API, launched in April 2026, uses a dedicated pipeline with specialized models for each task, offering superior speech accuracy with a 94.07% word accuracy rate and a 16.7% missed entity rate. It is also cost-effective at $4.50/hr compared to OpenAI's $18/hr, with a simpler developer experience allowing for quick deployment. OpenAI's Realtime API, utilizing a single multimodal model with broader language support, is suited for those embedded in OpenAI's ecosystem despite its higher cost and slightly lower speech accuracy. AssemblyAI's API is particularly advantageous for healthcare applications due to its Medical Mode and compliance features, making it a strong choice for production-scale voice agent use cases requiring high accuracy and cost efficiency.