As a side project, I've been building Lazyblink — a collection of free browser-based tools — and I recently added a set of subtitle utilities that solve a problem I kept running into: most online subtitle tools either upload your file to a server, slap on a watermark, or hide the useful part behind a signup.
So I built these to run 100% in the browser using JavaScript. The subtitle file never leaves your device, which matters when you're working with unreleased or client video.
What it does:
SRT ↔ VTT conversion — convert between the two most common subtitle formats
Transcript extraction — pull clean plain text out of an SRT/VTT file, stripping timestamps and cue numbers (useful for show notes, blog posts, or accessibility)
Timing shifter — move every caption earlier or later by a set number of seconds to fix out-of-sync captions
The interesting technical bit: because it's all client-side, the whole thing works as a static site with zero backend. Parsing SRT/VTT is basically splitting on blank lines, reading the --> timing line, and reformatting the timestamps (SRT uses commas for milliseconds, VTT uses periods — a small but easy gotcha).
If you work with video, it's here: https://lazyblink.com/subtitle-tools
It's free, no signup, no watermark. Happy to answer questions about the client-side approach, and open to feedback on what subtitle operations to add next.
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