Read manga in your language, in Firefox.
Sumi erases the original lettering and sets your language back inside the balloon, in the artwork, at the size that fits. Free to install, first page free with no account.
Firefox 128 or newer, on desktop.
What the translation actually looks like
Every extension in this category can say it works on the page you opened. The difference is what it leaves behind.
The original lettering goes away
Not a caption bar, not a tooltip. The Japanese is erased from the balloon and your language is typeset back into the same space, at a size that fits it. Flip back to the original at any time.
Vertical Japanese stays vertical
Tall CJK balloons are set in columns, right to left, the way they were drawn — instead of being rotated ninety degrees into a sideways line, which is where most general-purpose image translators give themselves away.
It reads as you scroll
Turn on auto-translate and each page is handled as it comes into view, including long vertical webtoon strips that never end.
It admits what it cannot read
Handwriting and drawn sound effects are genuinely hard. Regions Sumi is unsure about are marked rather than filled with a confident-sounding guess.
Installing it
1. Add it from Firefox Add-ons
One click from the listing. Mozilla reviewed the build; there is nothing to sideload and no developer mode to switch on.
2. Allow it on the site you are reading
Firefox asks for permission per site the first time. Sumi requests access only for the page you point it at.
3. Open a chapter and press translate
The first page is free with no account. A free account adds 5 pages, and 5 more to claim from your dashboard every day after that.
Firefox 128 or newer
The add-on declares strict_min_version 128.0. Older builds will not install it.
Desktop only, for now
Firefox for Android is not in the listing — it has not been tested, so it is not claimed. On a phone, the web translator below works in any browser with nothing installed.
Firefox questions
- Is the Firefox add-on free?
- Yes. Installing costs nothing, and the first page translates with no account at all. A free account adds 5 pages and 5 more to claim each day after that; Pro is for people reading whole series.
- Which Firefox versions work?
- Firefox 128 and newer, on desktop. Firefox for Android is not supported yet — it has not been tested, so it is not listed.
- Is it the same as the Chrome extension?
- Same version number, same engine, one difference in the manifest: Mozilla requires a data-collection declaration that Chrome does not have. Everything you actually use is identical.
- What does it ask permission for?
- Access to the page you ask it to translate, storage for your settings and page count, and a context-menu entry. Firefox asks per site, so it never has standing access to your browsing.
- Which sites does it work on?
- Official publisher readers are what we test against — Shonen Jump+, MANGA Plus, Comic Walker, Comic Days, Ganma, pixiv Comic and dozens more, including canvas-based readers that defeat ordinary image translators. Sumi does not host, index or link to scan sites.
- Can I get the newest build before Mozilla approves it?
- Yes — we publish the same build as a zip you can load yourself. It is the same code that goes to the stores, just ahead of review. The current self-hosted build is 0.9.19.
Not in Firefox right now?
The same translator runs as a Chrome extension, as a Safari extension on iPhone, iPad and Mac, and as an app that imports a folder or a ZIP. Sumi is also on Android (open testing on Google Play).