Guide

A Language Reactor alternative for studying your own files

If you use Language Reactor, you already believe the core idea: real native content is the best way to learn a language. So why look for an alternative? Because of where that study session lives — inside the streaming tab, in the moment.

Language Reactor (and Migaku, Voracious, asbplayer, Subadub) are subtitle tools layered over a video while you watch it. The dual subtitles, the hover lookups, the click-to-save make a Netflix or YouTube episode into a study session — but the help evaporates when the tab closes. It doesn't reach the video file on your drive, the podcast in your app, the PDF you're reading, or the ebook on your shelf, and the words you looked up don't come back later, when you're about to forget them.

What a "your own files" alternative changes

Langcap works from the source itself instead of from the streaming tab. You drop in a video, an audio file, an ebook, a PDF, or a web page, and it:

• Mines the whole source into questions — short, answerable ones, each stitched back to the exact clip, line, or page it came from. Not a subtitle overlay you read once, but review that persists.
• Keeps asking. A spaced-repetition scheduler tracks each word in each direction and brings it back right as it's fading — the part a subtitle tool leaves to you and Anki.
• Runs on your machine. Speech and language models download once, then work offline. No account, nothing uploaded. Your files stay in your folders.

Every source you add becomes a card in a library, and each has two modes: Play (watch or listen it back with the words lighting up and a translation beneath) and Recall (the question loop scoped to just that source).

An honest comparison

Language Reactor is excellent at what it does — live subtitle study on streaming video, in the browser, cross-platform, free to start. If that's all you want, keep it. Langcap is the better fit when:

• you want to study your own files, not just Netflix and YouTube;
• you want the material to come back as review, not vanish with the tab;
• you care that it's local and private — nothing uploaded, works offline.

The honest caveats: Langcap is a young Windows app (macOS later) and needs a Vulkan-capable GPU. Seven languages have the full text-or-audio on-ramp today — English, Spanish, French, German, Italian, Portuguese, Chinese — and Japanese and Korean study from audio now, with their text voice coming.