What AI model powers the voice transcription?

The tool uses OpenAI's Whisper model running locally in your browser via WebAssembly. Whisper is trained on 680,000 hours of multilingual audio and supports transcription in over 99 languages with high accuracy.

Is my audio or recording uploaded to a server?

No. The Whisper model runs entirely within your browser. Your audio — whether from a file or your microphone — never leaves your device. Everything is processed locally on your CPU.

Can I transcribe live microphone input, or only audio files?

The tool supports both modes. You can upload a pre-recorded audio file (MP3, WAV, M4A, OGG, FLAC, WebM, etc.) for transcription, or you can record directly from your microphone and transcribe in real time.

What languages does the transcription support?

Whisper supports over 99 languages including English, Spanish, French, German, Japanese, Chinese, Korean, Portuguese, Russian, Arabic, Hindi, and many more. Language detection can be set to automatic or you can specify the language manually for better accuracy.

How accurate is the transcription?

Accuracy varies by language, accent, audio quality, and background noise. For clear English speech at studio quality, Whisper typically achieves a word error rate under 5%. Non-English languages and noisy environments may yield lower accuracy. You can edit the transcription text after it is generated.

Can I export the transcription?

Yes. After transcription, you can copy the full text to your clipboard or download it as a plain text (.txt) file.

Is there a file size or recording duration limit?

There is no server-imposed limit. The model runs locally, so the only constraints are your device's available memory and CPU performance. Very long recordings (over one hour) may take significant time to process.

Free AI Voice Transcription - Speech to Text Online

Need to transcribe audio or video to text? Our AI voice transcription tool uses OpenAI's Whisper model to automatically convert speech to text with high accuracy. Everything runs locally in your browser — no uploads, no accounts, complete privacy for your recordings.

What is AI Voice Transcription and How Does It Work?

AI voice transcription uses deep learning to convert spoken language into written text. Our tool uses Whisper, OpenAI's state-of-the-art automatic speech recognition model, which was trained on 680,000 hours of multilingual audio data. Whisper supports over 30 languages and delivers near-human accuracy for clear speech.

The model processes audio in 30-second chunks, converting each chunk into text with timestamps. For longer recordings, the audio is automatically split into overlapping segments to ensure no words are lost at chunk boundaries. You can see the transcription appear in real-time as words are decoded.

How to Transcribe Audio: Step-by-Step Guide

Using our free speech-to-text tool takes just a few steps:

Select the spoken language: Choose the language being spoken in the audio from the dropdown (defaults to English)
Upload a file or record: Drag and drop an audio/video file into the drop zone, or click the green Record button to record from your microphone
Watch the live transcription: The AI model loads on first use (cached for future visits), then processes your audio — text appears in real-time as it's decoded, with a progress indicator showing completion
Review and edit: Switch to the Editor tab to correct typos or errors in the transcription
Export: Copy the text to clipboard or save as a text file using the action buttons

Key Features

Real-time streaming: See words appear as they are decoded — no waiting for the entire file to finish
Append mode: Record or upload multiple times — each transcription appends to the existing text, building up a complete document
Built-in editor: Switch between the read-only Transcription view and an editable Editor to fix errors, rearrange text, or add notes
Translate to English: Enable the "Translate to English" checkbox to translate non-English speech directly to English text
Timestamps: Toggle "Show timestamps" to see time markers for each sentence segment
Sentence-separated output: Transcription is automatically formatted with line breaks between sentences for easy reading

Common Use Cases for Voice Transcription

Journalists, students, professionals, and content creators frequently need to convert speech to text for a wide range of purposes:

Meeting Notes: Transcribe recorded meetings, calls, and conferences to searchable text — never miss an action item or decision again.
Interview Transcription: Convert interviews into text for research, journalism, podcasting, and documentary production.
Lecture Notes: Record university lectures and generate study notes automatically — review an entire lecture in minutes instead of hours.
Content Creation: Transcribe podcast episodes, YouTube videos, and voiceovers for subtitles, show notes, and blog posts.
Accessibility: Generate text versions of audio content for hearing-impaired users and accessibility compliance.
Legal and Medical: Transcribe depositions, patient notes, and dictations with complete privacy — recordings never leave your device.
Language Learning: Transcribe foreign language audio to practice reading and verify pronunciation. Use the translate feature to get English translations.
Personal Notes: Record voice memos and thoughts, then convert them to organized text notes. Use append mode to build up notes over multiple recording sessions.

Understanding the Whisper AI Model

Our tool uses Whisper Base, a transformer-based encoder-decoder model optimized for browser deployment:

Architecture: Encoder-decoder transformer trained end-to-end on speech recognition, with log-Mel spectrogram input features
Model Size: Approximately 150 MB in quantized ONNX format — balancing accuracy and download size for browser use
Training Data: Trained on 680,000 hours of multilingual and multitask supervised data collected from the web
Language Support: Supports transcription in over 30 languages including English, Spanish, French, German, Chinese, Japanese, Korean, Russian, Arabic, and many more
Robust to Noise: Whisper handles background noise, accents, and varying audio quality better than traditional speech recognition systems
Lazy Loading: The model only downloads when you first use it (not on page load), and is cached in your browser for instant access on future visits

Supported Input Formats

The tool accepts a wide range of audio and video file formats:

Audio: MP3, WAV, OGG, FLAC, AAC, WMA, M4A, WebM audio
Video: MP4, WebM, MOV, AVI — audio track is automatically extracted
Recording: Direct microphone recording via the browser's MediaRecorder API

All audio is internally converted to 16kHz mono PCM format for optimal Whisper performance. The Web Audio API handles format conversion and resampling automatically.

Free Online Voice Transcription: Privacy and Security Features

Complete Privacy Protection

Our free voice transcription tool processes all AI inference locally in your browser using Transformers.js with WebGPU acceleration (WASM fallback). No audio is ever uploaded to servers, no cloud processing occurs, and no account is required. The Whisper model (~150 MB) is downloaded once and cached in your browser for instant access on all future visits.

Technical Details: How the Transcription Pipeline Works

For technically curious users, here is a breakdown of what happens when you start a transcription:

Step 1: Audio Preprocessing

The uploaded file is decoded using the Web Audio API, which handles format conversion from MP3, AAC, OGG, and other formats. The audio is resampled to 16kHz mono — the format Whisper expects — and converted to a Float32Array of PCM samples.

Step 2: Chunked Processing with Streaming

Long audio is automatically split into 30-second chunks with 5-second overlapping strides. As each chunk is processed, decoded words stream to the UI in real-time via the WhisperTextStreamer, so you see text appearing as it's generated.

Step 3: Whisper Inference

Each audio chunk is converted to a log-Mel spectrogram and fed through the Whisper encoder-decoder transformer. The model generates text tokens autoregressively, with attention mechanisms allowing it to handle varying speech rates, accents, and background noise.

Step 4: Text Assembly

Transcribed chunks are assembled into the final text output with sentence-level formatting. Overlapping regions are resolved to prevent duplicate text at chunk boundaries. The final result replaces the streaming preview with properly formatted sentences.

AI Transcription vs Alternative Approaches

Approach	Pros	Cons	Best For
AI Transcription (Whisper)	Fast, accurate, 30+ languages, completely private, built-in editor	May struggle with heavy accents or very noisy audio	General-purpose transcription with privacy requirements
Manual Transcription	Perfect accuracy, handles any audio quality	Extremely slow (4-8 hours per hour of audio), expensive	Legal, medical, or archival transcription requiring perfection
Cloud Transcription Services	High accuracy, speaker diarization, real-time	Audio uploaded to third-party servers, subscription costs	Enterprise use where privacy is not a concern
Built-in Speech Recognition	No download required, real-time	Limited languages, lower accuracy, often cloud-based	Simple dictation and voice commands

Tips for Best Transcription Results

Use Clear Audio

Whisper performs best with clear speech and minimal background noise. If possible, use a dedicated microphone rather than a laptop's built-in mic, and record in a quiet environment.

Select the Correct Language

Always select the language being spoken from the dropdown. This is required for accurate transcription — the tool does not auto-detect language. Selecting the wrong language will produce garbled output.

Moderate Speaking Speed

Very fast or very slow speech can reduce accuracy. Natural conversational pace produces the best results. Whisper handles pauses and filler words well.

Use the Editor for Corrections

After transcription, switch to the Editor tab to fix any errors. The editor provides a separate editable copy — your original transcription is preserved in the Transcription tab.

Frequently Asked Questions

How large is the AI model and how long does download take?

The Whisper model is approximately 150 MB. It only downloads when you first click Record or upload a file — not on page load. Download time depends on your connection speed — typically 15 seconds to a minute. After the first download, the model is cached in your browser and loads instantly on all subsequent visits.

How long does transcription take?

On modern hardware, Whisper processes audio faster than real-time — a 60-second recording typically takes 5-10 seconds to transcribe. You can watch the text appear in real-time as it's being decoded, with a progress indicator showing overall completion.

What languages are supported?

The tool supports over 30 languages including English, Spanish, French, German, Italian, Portuguese, Russian, Chinese, Japanese, Korean, Arabic, Hindi, and many more. You must select the spoken language from the dropdown — the language you choose tells the AI what language to expect.

Can I translate speech to English?

Yes. Enable the "Translate to English" checkbox to have Whisper translate non-English speech directly into English text. This is a built-in capability of the Whisper model.

Are my recordings uploaded anywhere?

No. Your audio never leaves your device. All processing — audio decoding, AI inference, and text generation — happens entirely within your browser. There is no server involved at any point.

Can I transcribe video files?

Yes. The tool accepts common video formats (MP4, WebM, MOV, AVI) and automatically extracts the audio track for transcription.

Can I add more recordings to an existing transcription?

Yes. Each new recording or file upload appends to the existing transcription text. This allows you to build up a complete document over multiple recording sessions — great for meeting notes or interview transcription.

Does it work offline?

After the initial model download, the tool works with locally stored files without an internet connection. The model is cached in your browser storage. However, microphone recording requires a secure context (HTTPS).

A Note on Accuracy

AI transcription produces highly accurate results for clear speech but is not perfect. Background noise, heavy accents, overlapping speakers, and domain-specific terminology may reduce accuracy. Use the built-in Editor to review and correct the transcription for critical use cases.

Why Choose Our Free Online Voice Transcription?

Complete Privacy: All AI processing happens locally in your browser — audio is never uploaded to any server
State-of-the-Art AI: OpenAI Whisper model for high-accuracy speech recognition
Real-time Streaming: Watch words appear as they are decoded — no waiting for the entire file
30+ Languages: Transcribe speech in over 30 languages with translation to English
Built-in Editor: Switch to editor mode to correct errors without leaving the tool
Append Mode: Build up documents over multiple recording sessions
Multiple Input Methods: Upload files or record directly from your microphone
Timestamps: Optional timestamp display for navigating long transcriptions
Audio and Video: Accepts audio files (MP3, WAV, OGG, FLAC) and video files (MP4, WebM, MOV)
No Account Required: No registration, no login, no usage limits
Model Caching: One-time download, instant loading on all future visits
WebGPU Accelerated: Uses GPU acceleration when available for faster processing