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Latest Release
Text-to-Speech API
Our first text-to-speech model, AssemblyAI-TTS-1, is built for voice agents, on live calls. It sounds natural, responds fast, and keeps callers on the line.
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We're giving Biography podcast listeners $100 in free credits to try AssemblyAI's speech-to-text and Speech Understanding models. We can't wait to see what you build.
She was born in Vienna in 1931, the youngest of four.
And that early period shaped everything that came after.
Let's trace the story from there.
Get clean, customizable transcripts in 99 languages with industry-leading accuracy and natural language prompting.
Build voice agent workflows with ultra-low latency, high accuracy, and precise end-of-turn control.
Turn raw audio into structured, actionable intelligence. Purpose-built models extract meaning from speech in a single API call.
36%
improvement in close rate
“The new Universal-3.5 Pro speech model from AssemblyAI is best so far in terms of accuracy, latency, and language switching.”
80%
increase in customer satisfaction
“Assembly has saved us countless hours managing models, and provided exceptional accuracy.”
36%
improvement in close rate
“The new Universal-3.5 Pro speech model from AssemblyAI is best so far in terms of accuracy, latency, and language switching.”
80%
increase in customer satisfaction
“Assembly has saved us countless hours managing models, and provided exceptional accuracy.”
Create a free account, drop in your API key, and transcribe your first file in minutes. Test in the no-code playground, then copy a ready-made request into your app—the credits are already waiting.
Claim $100 in free creditsNo credit card required
Your product is only as good as the inputs it's built on. Word error rate is the share of words the model gets wrong against a human reference—the standard measure of Speech-to-Text accuracy.
Average normalized WER across synthetic medical, accented English, general speech and webinar sets.
*Lower is better*Source: AssemblyAI published benchmarks (assemblyai.com/benchmarks), pre-recorded tab, updated July 2026.
