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Sync Speech-to-Text API

API service

by AssemblyAI

Returns a transcript of a short audio clip in a synchronous API response.

Find alternatives to Sync Speech-to-Text API

What it does

• Speech to text

Features 3

• Per-word timing and confidenceEvery response includes per-word text, timing and confidence.
• Keyterms prompting and contextKeyterms prompting and conversation context are included in the Sync API.
• 18 supported languagesSupports 18 languages at flagship single-call accuracy.

Sources

Pricing

Pricing page · 14 Oct 2026

"Pay as you go"

Description

Official documentation · 14 Oct 2026

"Send a short clip and receive a transcript"

What it does

Official documentation · 14 Oct 2026

"One call, one finished transcript"

Sold within

Official documentation · 14 Oct 2026

"transcribe an audio file synchronously with the Sync API."

Name

Official documentation · 14 Oct 2026

"What is the Sync Speech-to-Text API?"

URL

Official documentation · 14 Oct 2026

"What is the Sync Speech-to-Text API?"

Deployment

Official documentation · 14 Oct 2026

"call the Sync API over HTTP"

Interfaces

Official documentation · 18 Oct 2026

Page: 'You send a short audio clip (up to 2 minutes) in a single HTTP request and get a finished transcript back in the same response'.

Also from AssemblyAI

• AssemblyAI Pre-recorded Speech-to-Text API API service

  Speech-to-text API for recorded audio and video files: transcripts in 99 languages with speaker diarization, language detection, word-level timestamps and keyterm prompting, billed per second of audio.

• AssemblyAI Realtime Speech-to-Text API API service

  Live transcription API: audio streamed over a WebSocket comes back as text within a few hundred milliseconds, with endpointing for voice agents, sold by the hour of session time and also offered self-hosted.

• AssemblyAI Voice Agent API API service

  One connection that runs a production voice agent end to end: speech recognition, a conversational language model, voice generation, turn detection, interruptions and tool calls, at one flat hourly rate.

• AssemblyAI Speech Understanding API API service

  Add-on models switched on in a transcription request that turn recorded audio into structured output: speaker labels, sentiment, entities, topics, key phrases, summaries, translation and custom formatting, each priced per audio hour.

• AssemblyAI LLM Gateway API service

  OpenAI-compatible API that routes requests to GPT, Claude, Gemini, Qwen and other hosted models with automatic fallbacks, at the providers' own token prices with no markup, beside AssemblyAI's speech APIs.

• AssemblyAI Guardrails API service

  Safety add-ons for transcription requests: profanity filtering, content moderation and redaction of personal data in the transcript text and in the audio itself, each toggled per request.

• Dictation API API service

  Converts spoken audio into text with a cleanup pass and an accompanying verbatim transcript.

• Blurt Application

  Converts speech into text wherever the user is typing.

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