{"id":"assemblyai-tts-1","slug":"assemblyai-tts-1","name":"AssemblyAI-TTS-1","orgId":"assemblyai","family":"assemblyai-tts-1","releaseDate":null,"availability":"announced","openWeights":false,"license":null,"paramsTotal":null,"paramsSource":null,"contextWindow":null,"knowledgeCutoff":null,"modelCardUrl":"https://www.assemblyai.com/blog/text-to-speech-api","hfRepo":null,"modalities":["audio"],"aliases":["AssemblyAI-TTS-1","assemblyai-tts-1","assemblyai tts 1","assemblyai tts-1","assemblyai tts"],"aliasNote":null,"origin":"tracked","tracked":{"trackedSince":"2026-10-28","announced":"2026-10-27","blurb":"AssemblyAI's first text-to-speech model, aimed at voice agents: streaming audio over HTTP or WebSocket, more than 4,000 voices and instant voice cloning, in English, Spanish, French, German, Italian and Portuguese. Generally available on AssemblyAI's API at $15 per 1M characters with no concurrency limit or annual contract. No weights.","api":"live","apiModelId":"assemblyai-tts-1","openWeights":"no","facts":[{"label":"Task","value":"Text-to-speech for voice agents; operates on continuous audio representations rather than discrete audio tokens"},{"label":"Languages","value":"English, Spanish, French, German, Italian and Portuguese, with several accents; more languages promised"},{"label":"Voices","value":"4,000+ library voices plus instant voice cloning; no fine-tuned (\"Pro\") cloning yet; pronunciation dictionaries and emotion tags coming"},{"label":"API","value":"assemblyai-tts-1: HTTP POST /v1/speech and WebSocket /v1/ws on tts.us.assemblyai.com, an OpenAI-compatible route, and an EU host"},{"label":"Pricing","value":"$15 per 1M characters; unlimited concurrency, no annual contract"},{"label":"Training data","value":"Millions of hours of audio, including real conversational data, per AssemblyAI"},{"label":"Weights","value":"None"}],"claims":["Lab claim: 47 ms median time to first byte in AssemblyAI's head-to-head with five other TTS models (next fastest 119 ms), and 90 ms time to first audio in production.","Lab claim: 99.0% word accuracy, 93.7% entity accuracy, 3.85/5 average on preference predictors such as UTMOSv2, 85.5 on TTSDS prosody and 0.64 cloned-voice speaker similarity."],"sources":[{"kind":"lab","title":"AssemblyAI blog: AssemblyAI-TTS-1 text-to-speech API","url":"https://www.assemblyai.com/blog/text-to-speech-api","date":"2026-10-27"},{"kind":"lab","title":"AssemblyAI docs: text-to-speech voices","url":"https://www.assemblyai.com/docs/tts/voices"},{"kind":"lab","title":"AssemblyAI on X: AssemblyAI-TTS-1","url":"https://x.com/AssemblyAI/status/2115470615583056042","date":"2026-10-28"}],"firstBenchmark":null},"organization":{"id":"assemblyai","name":"AssemblyAI","slug":"assemblyai","country":null,"url":null,"color":"#A39E8F","mark":"AS"},"price":null,"answer":{"word":"Pending benchmarks.","scope":"Announced Oct 27, 2026; no independent results yet.","lead":"As of Nov 3, 2026, AssemblyAI-TTS-1 is pending benchmarks on isitsota: announced Oct 27, 2026, with no independent results on the boards we track yet.","confidence":"low"},"status":"PENDING_BENCHMARKS","verdicts":[]}