A subtitle editor in which the translator approves a brief on characters and context before translation, then refines the text and timing against the video preview.
In development, in English and Polish. contextsub.com is public; access to the studio is limited for now.
Our own Localize.pl project, not client work.
A subtitle translator works with dialogue cut off from the picture. Who is speaking, to whom, and whether it is irony: that information is on screen, not in the subtitle file. On top of that come hard limits: reading speed, line length and display time.
ContextSub brings both into one tool. It has been built for the international market from day one.
The analysis prepares a description of characters, relationships and terminology. The translator corrects and approves it before the model translates everything, so decisions about tone and naming are made once rather than in every line.
Character and event descriptions point to the parts of the material they come from. You can check where an interpretation came from instead of taking it on trust.
The editor checks reading speed (CPS), line length, display time and overlaps. Linguistic quality and technical readability are checked in the same place.
With a local video file, the video never leaves the device. The analysis receives the subtitles and, for a fuller analysis, selected frames.
Media analysis runs in a separate process started on demand, so the editor stays responsive.
| Technology | Role |
|---|---|
| React, Vite, TypeScript, Zustand | Editor, timeline and the translator’s working state |
| Fastify, PostgreSQL (Neon) | API and project data |
| Node.js, FFmpeg | Separate media analysis process |
| AI models | Linguistic and visual analysis |
| Vercel, Railway, file storage | Hosting for the editor, analysis process and media |
The product is in development. Sign-ups and sales will open once payments are in place; until then access to the studio is limited.
As of 28 September 2026.
Tell us about your process. We will check whether a similar approach makes sense for you.
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