AssemblyAI Speech-to-Text and Voice AI

AssemblyAI provides speech-to-text APIs, audio intelligence models, and an LLM Gateway for applying language models to transcripts. This skill corrects common mistakes that training data gets wrong — deprecated APIs, discontinued SDKs, and non-obvious auth patterns.

Authentication

All endpoints use the same header:

Authorization: YOUR_API_KEY

NOT Authorization: Bearer ... — just the raw API key, no Bearer prefix. This is the #1 mistake.

Base URLs