Online Subtitle Editor

What the editor is for

Subtitles usually arrive nearly right and needing a correction pass, or written elsewhere and never checked against the picture. Both jobs go faster with the video, the words and the timing in one window. Change a word, a start time or the font and the preview redraws at once.

It opens MP4, MOV, M4V, WebM and MKV files from your computer, and the subtitles can come from AI, an imported SRT or VTT file, or lines you type at the playhead. You leave with an SRT or VTT file, a rendered MP4 with the subtitles in the frame, or both.

With AI switched off, the video and your text stay on your computer. AI subtitles upload only the audio track, never the picture.

A tour of the workspace

Preview

Your video with the current subtitles drawn on top by the same layout code the final render uses, so line breaks and placement match the download. Play, pause, step a second back or forward, mute, and change the speed from 0.5× to 2×.

Subtitles tab

One row per line with its number, a start and an end time you can type into, the duration, a text box and a delete button. The line being spoken is highlighted and the list scrolls with playback.

Timeline

Every line drawn as a block under a time ruler. Click empty space to move the playhead, drag a block to move it, drag either edge to change when it starts or ends. A zoom slider and a Fit button control how much you see.

Toolbar

Import SRT / VTT, Export SRT, Export VTT, Add subtitle, Split, Merge, Delete, Undo, Redo, and a "Shift all by" box for moving the whole set.

Style tab

Eight presets, 19 fonts, colours, background, position, a safe-area guide, and a blur band for subtitles that are already burned into the video.

Warnings that catch problems early

Each row checks itself as you edit and lists any problem underneath. The Subtitles tab shows a count of lines with warnings, and their blocks are marked on the timeline, so you can find them without reading every row.

• End before start, or no duration at all.
• Shown for under 0.8 seconds, which is too brief to read.
• Overlapping the line before or after it.
• Too fast to read: more than 21 characters per second for Latin and most other scripts, with lower limits for Japanese, Chinese, Korean and Thai.
• A line longer than 42 characters (fewer for Chinese, Japanese, Korean and Thai). It will wrap, but you may prefer to break it yourself.
• No text, in which case the line is skipped on export and render.
• More than three lines, which starts to cover the picture.

Warnings are advice, not blockers. The render summary tells you how many remain so you can decide whether to go back. For the fixes themselves, splitting and merging lines and changing subtitle timing go into detail.

Undo, drafts and other safety nets

Undo keeps up to 200 steps and covers text, timing and style alike. A burst of typing in one line is grouped into a single step, a timeline drag counts as one step however far you pull, and even importing a file or accepting a batch of AI subtitles can be undone if the result isn't what you wanted.

Your work is also saved as a draft in this browser shortly after each change: the lines, the style and the blur band, for up to five videos. Open the same video file again and the draft comes back. Drafts are matched on the file's name, size and date, so a renamed or re-exported copy starts fresh. The video itself is never stored. Clearing site data removes drafts, so on long jobs export an SRT now and then as a backup.

Keyboard shortcuts

• Space: play or pause.
• Left and Right arrows: jump one second; hold Shift for a tenth of a second.
• Up and Down arrows: select the previous or next line and jump the video to its start.
• Enter: add a new line at the playhead and put the cursor in it.
• Delete or Backspace: remove the selected line.
• Ctrl+Z or Cmd+Z: undo. Ctrl+Shift+Z, Cmd+Shift+Z or Ctrl+Y: redo.

The single-key shortcuts stand aside while the cursor is in a text or time box, so typing a space or pressing Enter inside a line does what you'd expect. Undo and redo work everywhere.

Editing a set of subtitles from start to finish

1. Open the editor on this page and choose your video. Leave "Write the subtitles automatically with AI" on for a first draft, or switch it off if you already have text.
2. To start from a file, click Import SRT / VTT. The notice tells you how many lines came in and whether any blocks were unreadable.
3. Play the video at normal speed or 0.75× and read along. Press Up or Down to step through lines and fix words in the text boxes as you go.
4. Correct timing by dragging blocks on the timeline or typing exact times into a row. If every line is late by the same amount, use Shift all by instead.
5. Work through the rows that carry warnings. Split lines that are too long, merge fragments, and give short lines more time.
6. Open Style, choose a preset close to what you want, then adjust font, size, colours and position. Turn on Show safe area to check the edges.
7. Click Export SRT or Export VTT for a subtitle file, or Render video for an MP4 with the subtitles burned in.

If the subtitles came from AI, fixing auto-generated subtitles suggests an order for step 3 that catches names, numbers and homophones first.

Limits worth knowing

• One style for the whole video. You can't colour, enlarge or move a single line, and italics or colour tags in an imported file are dropped.
• Lines appear and disappear whole. There are no animated or word-by-word effects.
• No speaker names or sound descriptions are generated; type them in if your audience needs them.
• ASS, SSA and SBV files aren't imported, and subtitle tracks stored inside an MKV aren't read. Convert or extract them to SRT first.
• The MP4 has the subtitles in the picture. A switchable track inside the file isn't written; the SRT and VTT exports are your soft subtitles.
• Rendering needs a desktop browser: Chrome or Edge 94+, Safari 16.4+ or Firefox 130+. On a phone or tablet you can still edit and export files.
• AI translation works from the speech in the video, so an imported file stays in whatever language it was written in.

Three typical sessions

How it compares with desktop tools

Desktop subtitle programs offer what this editor leaves out, such as per-line styling, waveform views and many more file formats. This one offers a short path from video to a checked, styled result with nothing to install. If you're weighing the options, our roundup of free subtitle editors sets them side by side. If all you need is a subtitle file and no editing, the AI subtitle generator is quicker, and once the words are right, burning subtitles into the video explains the render step in full.

About the subtitle editor on this page

Opens

MP4, MOV, M4V, WebM, MKV videos your browser can decode

Subtitles from

AI (from the speech, optionally translated into one of 21 languages), an SRT or VTT file, or typing them in

You download

An MP4 with the subtitles drawn into the picture at the original resolution and frame rate, plus SRT and VTT files

Cost

Editing, styling, rendering and SRT/VTT export are free, with no account and no watermark. AI subtitles cost 1 credit per minute (5-credit minimum per video); signing in with Google gives 100 free credits and accounts get 10 free credits a day

Privacy

The video never leaves your device and is rendered in your browser. Only for AI subtitles is the audio sent, over HTTPS, and it is deleted within 30 minutes of delivery

Rendering needs

Chrome or Edge 94+, Safari 16.4+, or Firefox 130+ on a computer. Editing and SRT/VTT export work in any current browser