Subtitle Editor with Video Preview
Load your video (it never uploads), edit each cue, click ▶ to jump the player to it, and export in any format.
Your subtitles and videos never leave your device — everything is processed locally in your browser.
Optional: drop a video for live preview
Your video NEVER uploads — it plays straight from your disk.
Drop the subtitle to edit
Edit text and times cue by cue, with live video preview
Frequently asked questions
Are my subtitle and video files uploaded to a server?
No. SubFix is 100% client-side: parsing, converting, syncing and even burning subtitles all happen inside your browser using JavaScript and WebAssembly. Your files never leave your device.
Which subtitle formats are supported?
SubFix reads and writes SRT, WebVTT (VTT), ASS, SSA and SBV (YouTube), and can also export plain TXT transcripts. Format detection is automatic.
How does hardcoding subtitles work without a server?
SubFix loads FFmpeg compiled to WebAssembly (about 32 MB, only when you use the burn tool) and renders subtitles onto the video frames locally. It works offline once loaded, but is slower than a desktop app — best for short clips.
Is SubFix really free?
Yes — free forever, no sign-up, no watermarks, no file-size games. Because your device does the work, our costs stay near zero.