Free Auto Captions: Subtitle Any Video Online
What Auto Captions does (and who it's for)
Captions make videos watchable on mute, accessible to deaf viewers, and searchable. The free Auto Captions tool from ZeroFee Tools generates subtitles for any video with unlimited minutes, then exports clean SRT or VTT files or burns captions straight into the video. Everything runs in your browser, so long videos never queue behind anyone.
How do I add auto captions to a video for free?
Upload your video to the Auto Captions tool, choose your language, and let it transcribe the speech into timed subtitles. Review the lines, fix any misheard words, then download an SRT or VTT file or export the video with captions burned in. The whole process takes a few minutes and costs nothing.
SRT files work with YouTube, Vimeo, and most players; burn-in is best when captions must show everywhere.
Are automatic captions accurate enough to publish?
Automatic captions are a strong first draft, typically accurate on clear, single-speaker audio, but homophones, names, and heavy accents can trip recognition. Always skim the transcript before publishing: a quick proofread of technical terms and proper nouns turns rough auto captions into publish-ready subtitles in minutes.
Recording with a close mic in a quiet room does more for accuracy than any setting.
The honest technical note: it uses your browser's built-in speech recognition, which listens through your microphone - you play the video aloud (speakers on) in a quiet room while it listens. Chrome and Edge support this best; Firefox and Safari have limited support.
How to caption a video, step by step
- Load your video. Click 📤 Choose video and select the file. Pick your Language for the recognition.
- Start auto-captions. Click 🎙 Start auto-captions, allow microphone access, and play the video aloud with speakers on in a quiet room. Captions appear with start/end timestamps as it listens.
- Fix timing and text. Click any caption to edit its Caption text, Start (sec), and End (sec). Missed a line? Use + Add caption to insert one manually.
- Style them. Set Caption color, Size, and Position - bottom-center is the classic, but top placement avoids covering on-screen text.
- Export. Download ⬇ SRT file (for YouTube/VLC) or ⬇ VTT file (for web players), or click 🔥 Burn captions into video to bake them permanently into a new MP4. Note: the first burn downloads a ~24MB video engine (cached afterwards), and encoding runs on your device.
4 practical tips for accurate captions
- Quiet room, loud speakers. Recognition quality lives or dies on audio clarity. Close windows, mute notifications, and turn speakers up - the mic hears what you hear.
- Speak one sentence ahead mentally. The recognizer lags real time slightly; don't pause the video the instant speech stops or you'll clip the last words of each caption.
- Fix proper nouns first. Auto-transcription mangles names, brands, and jargon. A quick pass correcting those makes captions look professional even if minor words are off.
- Keep lines short. Two lines max, ~40 characters each. Long single-line captions get auto-shrunk or overflow on phones - split them with + Add caption.
Frequently asked questions
Why does it need my microphone for a video file?
Browser speech recognition can only listen through the mic - web pages can't read a video file's audio track directly. So you play the video aloud while the tool listens. It's a browser limitation, not a design choice.
What's the difference between SRT, VTT, and burning in?
SRT and VTT are sidecar subtitle files - viewers can toggle them on/off (best for YouTube and accessibility). Burn captions into video bakes the text into the pixels permanently (best for Instagram/TikTok, where toggles don't exist).
My browser won't start auto-captions. What now?
Use Chrome or Edge, which have the best speech-recognition support. In Firefox or Safari, use the manual + Add caption form instead - it's always available and gives you full control.