SubFlow – In-browser subtitle burn-in studio

Add, style and burn subtitles into local videos without signup or uploads

Problem

When recording a short tutorial or internal video, adding a few subtitle lines to a local MP4 should be trivial, yet most tools force a signup or require uploading both the subtitle file and the video to the cloud. The original poster ended up solving it by recording voice-over instead, showing the need is simple but unmet.

Solution

A fully client-side video subtitle editor and burn-in tool: drag in a local MP4, split the timeline, type text, adjust font color and position, preview live, and export a video with hard-coded subtitles. No account, no backend, no watermark.

Users

People making tutorial videos at work, short-form video creators, ops and training staff who need subtitles on internal videos

MVP

Drag-and-drop local MP4 with duration detection; timeline segment and text editing; 3-5 built-in subtitle style presets; export hard-coded subtitles entirely in the browser; bilingual UI

Revenue

Free tier plus one-time Pro license for batch export, more styles and no watermark; or pay-per-export credits

Why now

Browser-based video encoding and WASM performance are now good enough to keep processing local, while AI-assisted development lets a solo dev ship a usable version quickly