Add Subtitles to Video, No Sign-Up Needed

Why most of the editor needs no account

An account on mydubly exists to hold credits and a history of AI jobs. The editor's ordinary work touches neither: your computer decodes the video, your browser keeps the lines, and the render happens in the tab. Nothing in that chain has a reason to know who you are.

So while signed out you can open an MP4, MOV, M4V, WebM or MKV file, type lines at the playhead or load a subtitle file with Import SRT / VTT, retime them on the timeline, split, merge and shift them, dress them in any of the eight presets and 19 fonts, blur old burned-in subtitles, export SRT or VTT, and render and download the MP4. The download carries no watermark either; subtitles without a watermark covers what is in the file.

The single prompt you can meet is for AI subtitles, AI translation included. They run on mydubly's servers and are paid in credits, credits need an account to sit in, and so the editor asks for a Google sign-in before it starts one.

The AI switch starts switched on

On the editor's first screen, under Choose video, there's a checkbox labelled "Write the subtitles automatically with AI". Out of the box it is ticked, and the choice is sticky: it's stored in this browser, so whatever you picked last visit is what you get. Untick it before you pick the file. The line under the drop area then talks about importing an SRT/VTT file or writing subtitles yourself, which is your confirmation.

If you forget, here's what happens and how to back out:

• Choosing a video with the switch on while signed out opens the sign-in window at once. Close it: the video stays loaded and every editing tool works.
• A note under the AI controls reads "Sign in and the subtitles start automatically." Take it literally. Sign in later in that session and the run begins and spends credits.
• To cancel that waiting run, import your SRT or VTT file, which clears it, or add a first line and close the AI bar with its × button.
• The checkbox only appears before a video is open. To change it afterwards, reload the page, untick it and choose the video again; a saved draft comes back with it.

One reassuring detail: when the video already has a draft in this browser, the AI doesn't start by itself even with the switch on, so reopening yesterday's work won't trigger a run.

Working through a video with no account

1. Open the editor on this page and untick "Write the subtitles automatically with AI".
2. Choose your video or drop it onto the box.
3. Bring in the words: Import SRT / VTT for an existing file, or press Space to pause where a line begins, press Enter and type.
4. Fix the timing by dragging blocks on the timeline or typing times in the line list, and deal with the warnings that matter.
5. Open Style, choose a preset, then adjust the font, size, colour and position.
6. Click Render video, read the "Ready to render" summary and start it.
7. Click Download video, and use Export SRT or Export VTT if you want the subtitle file too.

While the line list is empty, a slim AI bar above it offers "Sign in to generate". Ignore it; it steps aside once the first line exists.

What the editor keeps instead of an account

Without an account there's nothing of yours stored on mydubly's side. The work lives in this browser's local storage:

• Drafts: the subtitle lines and their timings, the style and the blur-band settings, saved a moment after each change.
• Up to five videos. Each draft is matched to its video by file name, size and last-modified time; the video itself is never written to storage.
• No expiry date. A draft stays until a sixth video pushes the oldest one out, you click "Start new video" after a render, or the browser's site data is cleared.
• Your AI switch setting and subtitle-language choice, so the editor opens the way you left it.

Because it belongs to this browser, a draft doesn't follow you to another computer, another browser or another browser profile, and a private window forgets it when closed. A renamed or re-exported copy of the video counts as a different file. The portable record is the subtitle file: Export SRT at the end of a session, and Import SRT / VTT picks up from there anywhere.

Why AI is the exception

Writing subtitles with AI uses server time, so it's paid in credits, and credits need an account to belong to. When it runs, your browser pulls out and compresses the audio and sends only that, over HTTPS, to be transcribed by Whisper; the picture stays on your computer, and the audio and text are deleted from the server within 30 minutes of delivery. A Google sign-in gives a new account 100 free credits, and registered accounts get 10 more each day. A run costs 1 credit per minute of video with a 5-credit minimum, so a 25-minute talk costs 25 credits (2.5¢).

With the switch off, the video, its audio and your text stay on your computer for the whole session. The no-upload route traces the data flow in detail, and free subtitle generation explains the credit allowance.

Who gets by without signing up

Limits that hold either way

Signing in changes who writes the first draft, not how the editor runs. Rendering still needs Chrome or Edge 94+, Safari 16.4+ or Firefox 130+ on a computer, while phones can edit and export subtitle files. The page needs the internet to load. AVI files aren't supported, and ASS or SBV files don't import. The output MP4 has the subtitles drawn into the picture; for a track viewers can switch off, upload the exported file next to the video, as adding an SRT to a video describes. If you'd rather start from scratch without AI, adding subtitles manually walks through the typing workflow. A plain transcript is a different job, handled by video to text, and for a ready-made SRT from speech there's the AI subtitle generator.

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