--- title: Grok STT description: xAI's Grok speech-to-text model. Transcribes audio files into text across 25 languages with word-level timestamps, multichannel transcription, speaker diarization, and key-term biasing. image: https://developers.cloudflare.com/dev-products-preview.png --- > Documentation Index > Fetch the complete documentation index at: https://developers.cloudflare.com/ai/llms.txt > Use this file to discover all available pages before exploring further. [Skip to content](#%5Ftop) ![xAI logo](https://developers.cloudflare.com/_astro/xai.2Y8IhZGx.svg) # Grok STT Automatic Speech Recognition • xAI `xai/grok-stt` xAI's Grok speech-to-text model. Transcribes audio files into text across 25 languages with word-level timestamps, multichannel transcription, speaker diarization, and key-term biasing. | Model Info | | | ----------------- | -------------------------------------------------------------------------------------------------------------- | | Terms and License | [link ↗](https://x.ai/legal/terms-of-service) | | More information | [link ↗](https://docs.x.ai/developers/model-capabilities/audio/speech-to-text) | | Pricing | [View pricing in the Cloudflare dashboard ↗](https://dash.cloudflare.com/?to=/:account/ai/models/xai/grok-stt) | ## Usage * [ TypeScript ](#tab-panel-2104) * [ cURL ](#tab-panel-2105) TypeScript ``` const response = await env.AI.run( 'xai/grok-stt', { url: 'https://storage.googleapis.com/cloud-samples-data/speech/brooklyn_bridge.mp3' },)console.log(response) ``` Terminal window ``` curl https://api.cloudflare.com/client/v4/accounts/$CLOUDFLARE_ACCOUNT_ID/ai/run \ --header "Authorization: Bearer $CLOUDFLARE_API_TOKEN" \ --header "Content-Type: application/json" \ --data '{ "model": "xai/grok-stt", "input": { "url": "https://storage.googleapis.com/cloud-samples-data/speech/brooklyn_bridge.mp3" }}' ``` * [ Output ](#tab-panel-2114) * [ Raw response ](#tab-panel-2115) How old is the Brooklyn Bridge? ``` { "state": "Completed", "result": { "text": "How old is the Brooklyn Bridge?", "language": "English", "duration": 1.85, "words": [ { "text": "How", "start": 0.14, "end": 0.28 }, { "text": "old", "start": 0.4, "end": 0.6 }, { "text": "is", "start": 0.65, "end": 0.75 }, { "text": "the", "start": 0.81, "end": 0.89 }, { "text": "Brooklyn", "start": 0.95, "end": 1.29 }, { "text": "Bridge?", "start": 1.35, "end": 1.69 } ] }, "gatewayMetadata": { "keySource": "Unified" }} ``` ## Examples **With Language and Formatting** — Enable Inverse Text Normalization so spoken numbers become digits * [ TypeScript ](#tab-panel-2106) * [ cURL ](#tab-panel-2107) TypeScript ``` const response = await env.AI.run( 'xai/grok-stt', { url: 'https://storage.googleapis.com/cloud-samples-data/speech/brooklyn_bridge.mp3', language: 'en', format: true, },)console.log(response) ``` Terminal window ``` curl https://api.cloudflare.com/client/v4/accounts/$CLOUDFLARE_ACCOUNT_ID/ai/run \ --header "Authorization: Bearer $CLOUDFLARE_API_TOKEN" \ --header "Content-Type: application/json" \ --data '{ "model": "xai/grok-stt", "input": { "url": "https://storage.googleapis.com/cloud-samples-data/speech/brooklyn_bridge.mp3", "language": "en", "format": true }}' ``` * [ Output ](#tab-panel-2116) * [ Raw response ](#tab-panel-2117) How old is the Brooklyn Bridge? ``` { "state": "Completed", "result": { "text": "How old is the Brooklyn Bridge?", "language": "English", "duration": 1.85, "words": [ { "text": "How", "start": 0.14, "end": 0.28 }, { "text": "old", "start": 0.4, "end": 0.6 }, { "text": "is", "start": 0.65, "end": 0.75 }, { "text": "the", "start": 0.81, "end": 0.89 }, { "text": "Brooklyn", "start": 0.95, "end": 1.29 }, { "text": "Bridge?", "start": 1.35, "end": 1.69 } ] }, "gatewayMetadata": { "keySource": "Unified" }} ``` **Speaker Diarization with Key Terms** — Identify speakers and bias transcription toward proper nouns * [ TypeScript ](#tab-panel-2110) * [ cURL ](#tab-panel-2111) TypeScript ``` const response = await env.AI.run( 'xai/grok-stt', { url: 'https://storage.googleapis.com/cloud-samples-data/speech/brooklyn_bridge.mp3', language: 'en', diarize: true, keyterm: ['Brooklyn', 'Manhattan'], },)console.log(response) ``` Terminal window ``` curl https://api.cloudflare.com/client/v4/accounts/$CLOUDFLARE_ACCOUNT_ID/ai/run \ --header "Authorization: Bearer $CLOUDFLARE_API_TOKEN" \ --header "Content-Type: application/json" \ --data '{ "model": "xai/grok-stt", "input": { "url": "https://storage.googleapis.com/cloud-samples-data/speech/brooklyn_bridge.mp3", "language": "en", "diarize": true, "keyterm": [ "Brooklyn", "Manhattan" ] }}' ``` * [ Output ](#tab-panel-2120) * [ Raw response ](#tab-panel-2121) How old is the Brooklyn Bridge? ``` { "state": "Completed", "result": { "text": "How old is the Brooklyn Bridge?", "language": "English", "duration": 1.85, "words": [ { "text": "How", "start": 0.14, "end": 0.28, "speaker": 0 }, { "text": "old", "start": 0.4, "end": 0.6, "speaker": 0 }, { "text": "is", "start": 0.65, "end": 0.75, "speaker": 0 }, { "text": "the", "start": 0.81, "end": 0.89, "speaker": 0 }, { "text": "Brooklyn", "start": 0.95, "end": 1.29, "speaker": 0 }, { "text": "Bridge?", "start": 1.35, "end": 1.69, "speaker": 0 } ] }, "gatewayMetadata": { "keySource": "Unified" }} ``` **Filler Words Preserved** — Keep filler words (uh, um, er) in the transcript instead of removing them * [ TypeScript ](#tab-panel-2108) * [ cURL ](#tab-panel-2109) TypeScript ``` const response = await env.AI.run( 'xai/grok-stt', { url: 'https://storage.googleapis.com/cloud-samples-data/speech/brooklyn_bridge.mp3', language: 'en', filler_words: true, },)console.log(response) ``` Terminal window ``` curl https://api.cloudflare.com/client/v4/accounts/$CLOUDFLARE_ACCOUNT_ID/ai/run \ --header "Authorization: Bearer $CLOUDFLARE_API_TOKEN" \ --header "Content-Type: application/json" \ --data '{ "model": "xai/grok-stt", "input": { "url": "https://storage.googleapis.com/cloud-samples-data/speech/brooklyn_bridge.mp3", "language": "en", "filler_words": true }}' ``` * [ Output ](#tab-panel-2118) * [ Raw response ](#tab-panel-2119) How old is the Brooklyn Bridge? ``` { "state": "Completed", "result": { "text": "How old is the Brooklyn Bridge?", "language": "English", "duration": 1.85, "words": [ { "text": "How", "start": 0.14, "end": 0.28 }, { "text": "old", "start": 0.4, "end": 0.6 }, { "text": "is", "start": 0.65, "end": 0.75 }, { "text": "the", "start": 0.81, "end": 0.89 }, { "text": "Brooklyn", "start": 0.95, "end": 1.29 }, { "text": "Bridge?", "start": 1.35, "end": 1.69 } ] }, "gatewayMetadata": { "keySource": "Unified" }} ``` **Data URI Upload** — Pass the audio file directly as a base64 data URI (mutually exclusive with \`url\`) * [ TypeScript ](#tab-panel-2112) * [ cURL ](#tab-panel-2113) TypeScript ``` const response = await env.AI.run( 'xai/grok-stt', { file: 'data:audio/wav;base64,<...>' },)console.log(response) ``` Terminal window ``` curl https://api.cloudflare.com/client/v4/accounts/$CLOUDFLARE_ACCOUNT_ID/ai/run \ --header "Authorization: Bearer $CLOUDFLARE_API_TOKEN" \ --header "Content-Type: application/json" \ --data '{ "model": "xai/grok-stt", "input": { "file": "data:audio/wav;base64,<...>" }}' ``` ``` { "state": "Completed", "result": { "text": "", "language": "", "duration": 1 }, "gatewayMetadata": { "keySource": "Unified" }} ``` ## Parameters * [ Input ](#tab-panel-2122) * [ Output ](#tab-panel-2123) file `string`Audio file as a data URI (data:audio/...;base64,...) or an HTTPS URL the gateway fetches and uploads. Supported container formats: flac, mp3, mp4, m4a, mkv, ogg, opus, wav, aac. Raw formats (pcm, mulaw, alaw) also accepted — supply audio\_format and sample\_rate. Gateway-side size limit: 25 MB. Mutually exclusive with \`url\`. url `string`format: uriHTTPS URL of an audio file for xAI to fetch server-side. Mutually exclusive with \`file\` and \`websocket\`. No gateway-side size limit applies. websocket `boolean`Enable WebSocket streaming for speech-to-text. When true, establishes a bidirectional WebSocket connection for real-time audio transcription. Mutually exclusive with \`file\` and \`url\`. audio\_format `string`enum: pcm, mulaw, alawFormat hint for raw/headerless audio. Required for pcm, mulaw, alaw. Omit for container formats (mp3, wav, etc.) — xAI auto-detects them. sample\_rate `integer`minimum: \-9007199254740991maximum: 9007199254740991Sample rate in Hz. Required when audio\_format is set. language `string`Language code (e.g. "en", "fr", "de"). Used with format=true to enable Inverse Text Normalization. xAI transcribes in any language regardless — supplying this enables number/currency formatting in the transcript. format `boolean`When true, enables Inverse Text Normalization — spoken numbers and currencies are converted to written form (e.g. "one hundred dollars" → "$100"). Requires language to be set. diarize `boolean`When true, enables speaker diarization. Each word in the response includes a \`speaker\` integer identifying the detected speaker. filler\_words `boolean`When true, filler words (uh, um, er) are included in the transcript. Defaults to false — filler words are removed. multichannel `boolean`When true, each audio channel is transcribed independently. Results are returned in the \`channels\` array. Requires channels ≥ 2. channels `integer`minimum: 2maximum: 8Number of audio channels (2–8). Required only for multichannel raw audio; auto-detected for container formats. ▶keyterm\[\] `array`maxItems: 100Key terms to bias transcription toward (e.g. product names, proper nouns). Each term up to 50 characters, max 100 terms. Sent as repeated form fields: keyterm=Term+One&keyterm=Term+Two. text `string`Full transcript text. language `string`Detected language name (e.g. "English", "French"). duration `number`Audio duration in seconds (2 d.p.). ▶words\[\] `array`Word-level segments. Each entry has text, start, end (seconds). Includes speaker integer when diarize=true. ▶channels\[\] `array`Per-channel transcripts when multichannel=true. ## API Schemas (Raw) Input [ ](https://developers.cloudflare.com/ai/models/xai/grok-stt/schema-input.json "Open") [ ](https://developers.cloudflare.com/ai/models/xai/grok-stt/schema-input.json "Download") Output [ ](https://developers.cloudflare.com/ai/models/xai/grok-stt/schema-output.json "Open") [ ](https://developers.cloudflare.com/ai/models/xai/grok-stt/schema-output.json "Download") ```json {"@context":"https://schema.org","@type":"TechArticle","@id":"https://developers.cloudflare.com/ai/models/xai/grok-stt/#page","headline":"Grok STT (xAI) · Cloudflare AI docs · Cloudflare AI docs","description":"xAI's Grok speech-to-text model. 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