Add Subtitles to Video
- Free
- No upload
- No watermark
Quick answer
To add subtitles to a video, either embed them as a soft track viewers can switch on and off, or burn them into the picture so they show everywhere. This tool does both in your browser: load a video and a subtitle file, or paste the text, check the live preview, then export. Soft subtitles are near-instant and lossless; burning in re-encodes the video. Nothing is uploaded.
Step by step
How to add subtitles to video
- 01
Add the video and subtitles
Drop in your video and a subtitle file (SRT, VTT, ASS/SSA, SBV, SUB, TTML/DFXP or LRC), or paste the text. The text needs timestamps: a plain transcript is not enough.
- 02
Check the live preview
The captions play over your video in the page, so you can check timing and wording first.
- 03
Choose soft or burned-in
Soft: pick the language tag. Burned-in: choose text size, white or yellow, outline or box, and top or bottom.
- 04
Export and download
Soft subtitles finish near-instantly. Burning in re-encodes the video on a single thread, so longer clips take a while.
In depth
Soft or burned-in subtitles: what is the difference?
Soft subtitles are a separate text track inside the video file; the player draws them, so viewers can switch them off and the picture is untouched. Burned-in subtitles, also called hard subtitles or open captions, are drawn into the frames, so they show in every app and can never be switched off.
| Aspect | Soft (embedded track) | Burned-in (hard) |
|---|---|---|
| Viewer can turn them off | Yes, from the player’s subtitle menu | No, always visible |
| Re-encoding | None: near-instant and lossless | Full H.264 re-encode; audio copied where MP4 allows |
| Styling | Left to the player | Size, white or yellow, outline or box, top or bottom |
| Instagram, TikTok, WhatsApp | May be ignored | Always shown |
| Language | Tagged on the track (English, Spanish…) | Part of the picture |
Which subtitle formats can you use?
SRT, VTT, ASS/SSA, SBV, SUB, TTML/DFXP and LRC all work, or paste the text. Plain text with no timestamps does not: the tool cannot invent timings, so it shows an error instead. For a transcript, make timed subtitles with Text to Subtitle first, then bring them here. Toolvy’s subtitle engine parses the file and detects its character encoding, with a menu to pick another if letters still look garbled, so accents from an old SRT arrive intact. A soft track is then written in each container’s own subtitle format:
- MP4 and MOV get a
mov_texttrack. - MKV gets an SRT track, or keeps an ASS file as ASS with its styling.
- WebM gets a WebVTT track.
- AVI and other formats that cannot hold a text track come back as an MKV.
How do you fix the timing before exporting?
Watch a few lines in the live preview. If every cue is off by the same amount, shift the file with the subtitle shifter; if only some lines are wrong, fix them in the subtitle editor. That saves exporting twice.
What if you have no subtitle file yet?
Make one from the speech. Pull the soundtrack out with Video to MP3, transcribe it on your device with Audio to Text, which exports SRT or VTT, then bring that file back here. To keep a copy in another format, the subtitle converter handles any pair.
How long does it take, and is anything uploaded?
Soft subtitles copy the video and audio unchanged and add a small text track, so export is near-instant. Burning in draws every frame with libass and re-encodes on one thread of ffmpeg.wasm, so short clips work best; compress it if the file is too big to send. Nothing is uploaded: the ~10 MB engine downloads once and runs in your tab.
Your files never leave your device
Processed locally in your browser — nothing is uploaded. You can verify it yourself: open your browser’s developer tools, watch the Network tab, and use the tool — no upload request is ever made.
- No file is ever uploaded to a server
- Works offline after the first visit
- No account, no watermark, no limits
A little more clarity
Frequently asked questions
01Why don’t my subtitles show on Instagram or TikTok?
Some social apps ignore embedded subtitle tracks when they process an upload, so a soft track never reaches the viewer. Export again in burned-in mode: the words become part of the picture, so they appear on Instagram, TikTok, WhatsApp and anywhere else the video plays.
02Can viewers turn the subtitles off?
With soft subtitles, yes. The captions sit in their own track, and viewers switch them on or off from the player’s subtitle menu, where your language tag labels the track. Burned-in subtitles are part of the image, so they are always visible.
03Does adding subtitles reduce video quality?
Soft subtitles do not touch the picture: the video and audio streams are copied as they are, so nothing is lost. Burning in redraws every frame, which means a full H.264 re-encode and, as with any re-encode, a small loss of quality.
04Which subtitle formats does it accept?
SRT, VTT, ASS/SSA, SBV, SUB, TTML/DFXP and LRC, or paste the subtitle text instead of choosing a file. Plain text with no timestamps is refused with an explanation rather than given invented timings; Text to Subtitle turns a transcript into timed subtitles. The subtitle engine reads each of these and detects its encoding, with a menu to fix garbled accents in an old SRT, before the preview.
05How do I add subtitles if I only have the video?
Create them from the speech first. Extract the soundtrack with the Video to MP3 tool, transcribe it with Audio to Text, which runs on your device and exports SRT or VTT, then load that file here and read through the preview, since automatic transcripts usually need a few corrections.
06Why is burning in subtitles so much slower?
Burning in draws text onto every frame and encodes the whole video again, and ffmpeg.wasm does that with a single thread in your browser, without the extra cores a desktop editor can use. Soft subtitles skip encoding, which is why they are near-instant.
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