Language Reactor is a Chrome extension, and no Safari version of it could be found. On a Mac you have two ways round that: a Safari extension built by someone else, or a tool that reads the subtitles off the screen so it does not matter which browser or player they are in.
Does it run on Safari?
Language Reactor does not run in Safari. It is built as a Chrome extension, and as of November 2026 no Safari build, Mac app or App Store listing for it turns up. Its forum shows people asking about other browsers since at least 2022, with one user noting that Safari was not mentioned at all.
What the team does say is about phones. In March 2026 a member of staff wrote that Language Reactor "does not have a mobile app for iOS or Android" and sent people to the website in a mobile browser. That is the website, not the subtitle extension, so it will not give you the YouTube overlay in Safari. The forum thread is public if you want to read it.
If you can use Chrome for this one job, that is still the simplest fix. If you would rather stay in Safari, read on.
Safari extensions that do something similar
Three options come up, and they are not the same kind of thing. Each was checked against its own page on 3 November 2026.
Tool
What it is on Safari
What to know
Trancy
A Safari extension, listed on its download page and in the Mac App Store as Trancy ET
YouTube bilingual subtitles and word translation. Needs macOS 13 or later. Free to download, with Premium listed at $2.99 a month or $29.99 a year.
Wordzzz
A free Safari extension in the Mac App Store
Its listing says it reads subtitles on YouTube and Netflix and pauses the video when you hover a word. That is the developer's description, not something that was tested.
Readlang
A bookmarklet you click in Safari
Built for reading text on web pages.
Captionpop is often listed as a Language Reactor alternative. The listings found for it are on the Chrome Web Store, so check before counting on it in Safari.
Readlang needs a caveat. Its own forum says the Safari guide was written for Safari 13, that you may have to turn off cross-site tracking, and that the bookmarklet "won't work on certain websites which prevent external scripts from running". It is a reader for text, which is a fine thing to be, but it is not a Language Reactor replacement. More on that in Readlang alternatives for Mac.
When the subtitles are not in a browser at all
Plenty of people watch with IINA, VLC or QuickTime, with a downloaded file and a subtitle track, and no browser is involved. A Safari extension cannot help there, and neither can Language Reactor in Chrome.
LeafyApp does not care what is playing. Press ⌥A, drag a box over the subtitle line, and macOS text recognition reads that patch of screen. The word you pick comes back explained for the sentence it sits in, and there is a separate shortcut to translate the whole boxed line. It works the same on YouTube in Safari, in IINA, in VLC, in QuickTime and on a video file you saved last year.
Pause on the line first. It is a still box over a still frame, which is why the recognition has time to be right.
What you keep afterwards
Every word you look up is saved with the sentence it came from, the source and the date. A week later you have a list of lines from the episodes you actually watched, not a list of bare words. The built-in review turns those sentences into fill-in-the-blank cards, and you can send them to Anki if that is where you study. The sentence mining page explains the habit.
What LeafyApp does not do
It is not a Language Reactor clone, and it would be unfair to let you think so.
There are no dual subtitles. You will not see the original and your language stacked under the video. There is no click-a-word subtitle bar either: you pause, press ⌥A and box the line yourself. Nothing follows the video along or auto-pauses on hover. It is a Mac app, not a browser extension, so there is nothing to install in Safari, and there is no Windows or iPhone version.
Protected streaming video often captures as a black frame on macOS, so test it first. Where the capture is black there is nothing for the recognition to read.
Which one to pick
If you watch YouTube in Safari and want clickable, stacked subtitles, try Trancy or Wordzzz. If you watch in IINA or VLC, or from files, or you want every line you looked up kept with its sentence, use LeafyApp. Some people will want both. They do not get in each other's way.
For subtitles burned into the video itself, no extension can help, and the screen translator page covers that case.
The picture is read on your Mac and thrown away. Only the word and its sentence go out so the AI can explain it, with nothing attached that says who you are, and your library stays on the Mac. The privacy page has the detail.
Questions people ask
Does Language Reactor work on Safari? No Safari version has been found. It is a Chrome extension, and as of November 2026 there is no Mac app either. Its staff only point iPhone users to the website in a mobile browser.
Is there a Language Reactor Safari extension? Not from Language Reactor. Trancy lists a Safari extension in the Mac App Store, and Wordzzz is a free Safari extension for YouTube subtitles, according to its listing.
Can I use Language Reactor on a Mac at all? Yes, in Chrome on the Mac. If you want to stay out of Chrome, use a Safari extension, or use LeafyApp to read subtitles in any player by boxing them with ⌥A.
What is a Language Reactor alternative for Safari? Trancy and Wordzzz run in Safari. LeafyApp is not an extension, but it reads subtitles in Safari, IINA, VLC and QuickTime without stacking two languages under the video.
Keep the browser. Add the player it misses.
Free while LeafyApp is in beta. One download, macOS 14 and up.
Language Reactor, Trancy, Wordzzz, Readlang, Captionpop, Netflix, Disney+, YouTube, IINA, VLC and QuickTime are trademarks of their respective owners. LeafyApp is an independent app, not affiliated with or endorsed by any of them, and the names are used here only to describe compatibility and for comparison.