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Automatic subtitles, no watermark
Subtitle generator, automatic subtitles you can fix
Make subtitles for a video automatically: a speech AI writes the words with their timings from a sound-only copy of the video, the tool splits them into lines that are easy to read, an AI cleans up punctuation and filler words, and you fix any word before you save. 3 minutes a day is free, 10 minutes when you sign in; the video never leaves your device.
- 3 minutes of automatic subtitles free a day
- Lines timed to the speech, easy to fix
- SRT, VTT, or burned into the video
Your video stays on your device. Typing, pasting or opening captions, every style and saving the new video happen in your browser. Auto captions send a sound-only copy, then its words for a clean-up, and only when you press Make captions.
Make captions automatically
AITo write the words, your browser makes a sound-only copy of the video and sends it through uncrop.si to an outside speech AI service, which sends back the words and when each one is spoken. The words that come back (never the sound) then go through uncrop.si to an outside AI service for a clean-up of punctuation and filler words. The picture is never sent, and we keep neither the sound nor the words.
For the most accurate captions, choose the language spoken. Detect automatically works for most videos and for languages not in the list.
Subtitle only part of the video
Type a time like 1:05.5 or 65.5, drag the handles, or play the video and use the current position.
Spread evenly shares the video's length among the captions, longer ones getting more time. Tap along plays the video while you tap a button, or press Space, as each caption starts.
Times in the file are kept. A TXT file without times goes into the box above, ready to spread or tap along.
Play the video, then tap this button or press Space as each line starts. After the last line, tap once more when it ends. Each line runs until the next one starts.
Speech AI can mishear names, numbers and words over music or noise, and now and then it adds words nobody said. Check each line before you save. Lines it was unsure about are marked.
Parts without captions
AI tools for these captions
AITakes out filler words such as um and uh, and puts back punctuation and capital letters. The times stay as they are.
Every caption keeps its times. Undo brings your captions back.
A caption with hashtags from what is said, and a title for YouTube.
A short summary and chapters with start times for a YouTube description. Needs at least a minute of captions.
These tools send only the words and times of your captions, never the video or its sound, through uncrop.si to an outside AI service, when you press one of them; the clean-up also runs by itself right after auto captions, and that one is free. Each press is one of today's 5 free AI caption runs (15 when you sign in); very long captions can count as two or more.
Estimated timing. Typed and opened captions say when each line starts and ends, not each word, so each word's moment is estimated from its length. To move the words, change the line's start and end.
The text and box colors are close, so the captions may be hard to read. Text on a box reads best with a contrast of at least 4.5 to 1.
Saving waits until auto captions or the AI tool finish. Styles can still be changed meanwhile.
Video with the captions burned in
Keep this tab open and the screen on until the video is saved. Locking the phone, or switching to another app or tab, stops the save.
Keep this tab open until it finishes.
Caption files
SRT and VTT keep the times, for YouTube and other players that let viewers turn captions on and off. TXT is the words alone, one caption a line, or with the time each line starts. For YouTube, upload the SRT as well as the video, so viewers can turn captions on and off and screen readers get the words.
Your captions and style are kept in this browser only, so you can come back to them with the same video. Start again on the Captions tab clears them.
How to make subtitles for a video automatically
Choose the video
Tap Choose a video and pick an MP4, MOV, WebM or MKV file, or drop it on the box.
Make the subtitles
Leave the language on Detect automatically or choose it, then press Make captions. The subtitles come back timed to the speech.
Fix and style
Fix any word, check the lines marked Check this line, and pick a style if you want them on the video.
Save
Save an SRT or VTT file to upload with your video, or save a new MP4 with the subtitles burned in.
Already have a subtitle file, or want only the text? Add subtitles to a video or Video to text.
What is sent, and what stays on your device
Your video is opened on your device and stays there. When you press Make captions, your browser makes a sound-only copy (one channel, compressed, without the file name or any tags) and sends it through uncrop.si to an outside speech AI service, which sends back the words and when each one is spoken. The words that come back (never the sound) then go through uncrop.si to an outside AI service for a clean-up of punctuation and filler words. The picture is never sent. We keep neither the sound nor the words; the speech service keeps nothing after it replies, and the clean-up service keeps requests only for a limited time for safety checks.
Subtitles that are easy to read
Speech AI hears words, not subtitles, so the tool builds the subtitles itself: at most two lines of 42 characters each, at least a second on screen, a new subtitle at the end of a sentence or at a pause, and it avoids ending a line on a word like "the" or "of". Those are the rules most subtitle style guides use, such as Netflix's for English (Netflix).
The timing comes from your video's sound: each subtitle starts as the voice starts (within a fifth of a second for nearly every line in our English tests), and leaves the screen soon after the speech ends, a little later when the next subtitle allows, so there is time to read it.
SRT or VTT, or burned into the video
| File | What it holds | Use it for |
|---|---|---|
| SRT (.srt) | Numbered captions, each with a start and end time | YouTube, Facebook, video editors and most players. YouTube takes .srt and .vtt caption files (YouTube Help) |
| VTT (.vtt) | The web's caption format: the same captions with WebVTT timings | Web players and the HTML video element (W3C) |
| TXT (.txt) | The words as plain text, with or without times | Notes, articles, show notes, quotes and search |
A file keeps the subtitles separate, so viewers can turn them on and off. Burning them in draws them onto every frame of a new MP4, on your device, so they show everywhere, including apps that do not take subtitle files.
Languages and translation
The speech AI understands many languages and detects which one is spoken. We tested it in English, Spanish, Portuguese, French, German, Arabic, Hindi and Japanese. Choosing the language before you start helps with short clips and with punctuation.
To subtitle in another language, make the subtitles, then press Translate and pick one of 37 languages. The translation keeps every subtitle's timing. It is one of your free AI runs: 5 a day, 15 when you sign in.
Free every day
Each day you get 3 minutes of automatic subtitles free, or 10 minutes when you sign in with Google, counted by the second, while the day's free pool for everyone lasts. Typing subtitles yourself, opening an SRT or VTT file, every style and saving the video have no limit and add no watermark.
Questions
Is this subtitle generator free?
Yes: 3 minutes of automatic subtitles a day, 10 minutes when you sign in, while the day's free pool for everyone lasts. Editing, styling and saving have no limit and no watermark.
Is my video uploaded?
No. The video stays on your device. When you press Make captions, a sound-only copy is sent to a speech AI service, then its words to an AI service for a clean-up. We keep neither, and the speech service keeps nothing after it replies.
Can I edit the subtitles?
Yes. Every line can be changed, split, merged or moved, and lines the speech AI was unsure about are marked so you can check them first.
Which subtitle files can I save?
SRT and VTT, which YouTube and most players take, and TXT for the text alone.
Can I translate the subtitles?
Yes, into 37 languages, keeping every subtitle's timing. Each translation counts as one free AI run (5 a day, 15 signed in).
Does it add a watermark?
No. Neither the subtitle files nor a video with burned-in subtitles carry a watermark.
Does it work in any language?
It understands many languages and detects which one is spoken. We tested English, Spanish, Portuguese, French, German, Arabic, Hindi and Japanese.
Sources: YouTube Help, Supported subtitle and closed caption files, W3C, WebVTT: The Web Video Text Tracks Format, Netflix Partner Help, English (USA) Timed Text Style Guide, caniuse, WebCodecs API
Open-source code and fonts this tool runs on your device: Mediabunny (MPL-2.0), unmodified, reads and writes the video and audio files; Noto fonts (OFL-1.1), Noto Sans Devanagari, Arabic, Thai and CJK and Noto Emoji, downloaded from uncrop.si only when your captions use a writing system your device has no font for; LAME (LGPL, source at SourceForge), the MP3 encoder (version 3.100) that makes the sound-only copy for auto captions in Safari and in browsers that cannot make an Opus one, built without its decoder for the browser by @mediabunny/mp3-encoder (MPL-2.0) and loaded only then.
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