Auto Caption Generator
AI generates automatic captions from your video's audio in seconds — review each line, translate into 100+ languages, then export an SRT or VTT closed-caption file ready for any platform.
- High-accuracy AI
- 100+ languages
- Line-by-line editor
- Fast turnaround
How it works
- Step 1
Upload your video
Drag in an MP4, MOV, or WebM file — audio is extracted in your browser, nothing is uploaded until you start.
- Step 2
Auto-generate captions
AI creates timed automatic captions from the speech and can auto-translate them into 100+ languages.
- Step 3
Review & export
Check every caption line by line, then export an SRT or VTT closed-caption track for YouTube, TikTok, or your editor.
Automatic captions for YouTube, TikTok, and Reels
Upload an MP4 or MOV and SubtitleFlow generates automatic captions straight from the audio — timed, punctuated, and ready to review. The AI handles the captioning end to end, so you skip manual transcription and hand-syncing.
- Auto-generate captions for YouTube, TikTok, Instagram Reels, Shorts, and course videos.
- Export an SRT or VTT closed-caption track, or upload it straight to the platform.
- Auto-translate captions into 100+ languages while the timing stays locked.
- Review every caption line by line before you publish.
Automated captioning runs in your browser — the video's audio is extracted locally and only the speech is processed, so even private clips stay private. Start captioning free with no signup, then upgrade only when you need longer videos.
Frequently asked questions
How does the auto caption generator work?
Upload an MP4 or MOV and the auto caption generator extracts the audio in your browser, then AI transcribes the speech into timed caption lines. You review and edit each line in the online editor, then export an SRT or VTT file — no manual transcription or hand-syncing.
Will the automatic captions stay in sync with my video?
Yes. Automatic captions are generated with precise start and end times from the spoken audio, and you can fine-tune any line in the editor before exporting — so the final SRT or VTT stays perfectly in sync.
Which platforms can I publish the captions to?
Export standard SRT or VTT files that work with YouTube, TikTok, Instagram, Bilibili, Premiere Pro, DaVinci Resolve, and most online players and editors.
Can I auto-translate the captions into other languages?
Yes. Generate captions in the original language, then auto-translate them into 100+ languages with context-aware AI while the timing stays locked.
Is automated captioning accurate?
Automated captioning uses speech-to-text AI to transcribe your video with punctuation and accurate timing. Accuracy is high on clear audio, and because you review every caption line by line before exporting, you can correct any name, term, or wording the AI misses.
Are my videos kept private while captioning?
Yes. The video's audio is extracted locally in your browser, captioning runs over an encrypted connection, results are stored privately to your account, never shared or made public, and removed under our data-retention policy.
How do I automatically caption a video for free?
SubtitleFlow auto-generates captions from your video's audio with accurate timing — upload an MP4 or MOV, let the AI create the caption lines, review them, and export SRT or VTT. Starting is free and needs no signup, and captions can be translated into 100+ languages.
Can I add automatic closed captions to my video?
Yes. The SRT or VTT file SubtitleFlow generates is a closed-caption track — upload it to YouTube, TikTok, or your player and viewers can toggle the automatic closed captions on or off. The AI creates the timed caption lines from your video's audio, and you can review every line before exporting.
What's the best AI auto caption tool?
SubtitleFlow is an AI auto caption tool that generates automatic captions straight from a video's audio with accurate timing, supports 100+ languages, and lets you review every line before exporting SRT or VTT — so you get platform-ready captions without manual transcription or hand-syncing.