Add Subtitles to Video

Yes. Every caption is rendered straight into the picture frames, so the text cannot be switched off, edited or restyled after the export. Keep your original clip and the subtitle file if you may want a different look later. Burned in captions always play, even in editors and social apps that ignore subtitle tracks.

SRT, VTT, ASS and SSA are all accepted. Whatever you upload is parsed on your device and rewritten as a clean SRT file before it is handed to the caption renderer, because SRT is the most predictable format for the bundled libass engine. If no cues are found, the tool tells you and stops instead of exporting a video without captions.

Subtitles have to be drawn onto every frame, so the clip is fully re-encoded rather than copied. As a rough guide, exporting takes between half of the video length and the full length, depending on resolution, frame rate and your machine. Short clips finish in seconds, while long 4K files can take several minutes.

The whole pipeline runs inside browser memory, so very large files can hit WebAssembly limits. Videos of a few hundred megabytes are comfortable on a desktop browser, while a phone or a laptop with little free memory may struggle sooner. If a big file fails, export a lower resolution copy first and try again.

You can set the font size, the text colour, the outline colour and weight, the position (bottom or top) and the vertical margin. Styling is limited to one bundled Latin font, so decorative layouts, karaoke effects and complex ASS positioning tags are not preserved, and non-Latin scripts are not covered by the built-in font.

Never. The subtitle parser and the FFmpeg engine both run locally through WebAssembly, so your video and your caption file stay on your device. There is no upload, no server, no account and no queue, and the exported file carries no watermark or branding.