{"id":81368,"date":"2025-08-18T13:54:21","date_gmt":"2025-08-18T20:54:21","guid":{"rendered":"https:\/\/blog.mozilla.org\/?p=81368"},"modified":"2026-03-23T15:15:36","modified_gmt":"2026-03-23T22:15:36","slug":"cjk-translation-on-android","status":"publish","type":"post","link":"https:\/\/blog.mozilla.org\/en\/firefox\/cjk-translation-on-android\/","title":{"rendered":"Firefox just got better for Chinese, Japanese and Korean speakers on Android"},"content":{"rendered":"\n
\"Two<\/figure>\n\n\n\n

When Firefox users ask for better translation support, we make it happen.<\/p>\n\n\n\n

Thanks to your feedback on Mozilla Connect<\/a>, Firefox now supports Chinese, Japanese, and Korean (often referred to as CJK) translation, both on desktop and Android. That means millions more people can browse and translate the web in their language, without sending their content to the cloud.<\/p>\n\n\n\n

\u201cWe saw so many requests on Mozilla Connect for CJK support,\u201d said Marco Castelluccio, engineering manager. \u201cIt was clear. This is what users wanted us to prioritize.\u201d<\/p>\n\n\n\n

Translation without tracking<\/strong><\/h2>\n\n\n\n

Unlike other browsers that send your content to the cloud for translation, Firefox handles everything locally on your device. That means more privacy, more control, and it even works offline once the language model is downloaded.<\/p>\n\n\n\n

\u201cFirefox automatically downloads the model once,\u201d explained Erik Nordin, software engineer. \u201cAfter that, translations happen on your phone. The content never leaves your device, and Firefox does not track what you translate.\u201d<\/p>\n\n\n\n

On-device translation requires efficiency. Mobile devices have limited memory and processing power, so the team developed smarter translation algorithms that prioritize the content you\u2019re actually reading. <\/p>\n\n\n\n

\u201cIf you\u2019re only reading the top of a long page, Firefox won\u2019t waste time and energy translating the whole thing,\u201d Erik said.<\/p>\n\n\n\n

This approach is part of Mozilla\u2019s broader mission to build technologies that respect your privacy by design. No compromises.<\/p>\n\n\n\n

We took our time to get it right <\/strong><\/h2>\n\n\n\n

Chinese, Japanese and Korean use characters, grammar and sentence structures that vary significantly from Latin-based languages. <\/p>\n\n\n\n

\u201cOur earlier translation algorithms were not able to handle writing scripts that do not insert a space character between sentences,\u201d Erik said. \u201cCJK languages required us to rethink both the architecture and how we algorithmically segment text.\u201d<\/p>\n\n\n\n

And there\u2019s simply less open-source data available to train CJK translation models compared to European languages.<\/p>\n\n\n\n

\u201cOur models are trained completely on publicly available data,\u201d said Marco. \u201cThat\u2019s important for transparency, but it also means it\u2019s harder to find enough good-quality examples for CJK languages.\u201d<\/p>\n\n\n\n

To make things even trickier, Firefox translation works locally. That means the models had to be smart enough to handle these complex languages and lightweight enough to run on mobile phones.<\/p>\n\n\n\n

\u201cWe had to rework our algorithms to make translation feel faster and more responsive,\u201d Erik said. \u201cNow, Firefox prioritizes the part of the page you\u2019re looking at instead of translating everything at once.\u201d<\/p>\n\n\n\n

To overcome these challenges, the team upgraded their machine learning models, overhauled the sentence segmentation pipeline, and optimized performance to ensure a smooth experience \u2014 especially on older and low-end Android devices.<\/p>\n\n\n\n

What stuffed mushrooms taught us about machine learning<\/strong><\/h2>\n\n\n\n

Mozilla engineers don\u2019t speak every language we support. That\u2019s why we leaned on the community and our collegues to help test CJK translation before launch. Volunteers tried out early versions in Firefox Nightly and flagged issues.<\/p>\n\n\n\n

\u201cThat feedback was gold,\u201d Erik said. \u201cIt helped us tweak the models and make sure the translations made sense in real-world use.\u201d<\/p>\n\n\n\n

And it was essential. Neither Marco nor Erik speaks any of the CJK languages. (Marco speaks Italian and English, and Erik is fluent in English with conversational Spanish.) To validate accuracy, they relied on community testers, Mozillians fluent in Chinese, Japanese or Korean, and members of MozAPI, Mozilla\u2019s resource group for Asian and Pacific Islander employees.<\/p>\n\n\n\n

\u201cOne tester pointed out a restaurant menu item translating ‘stuffed mushrooms’ as a plush toy,\u201d Erik laughed. \u201cIt was a great reminder of how nuanced language can be.\u201d<\/p>\n\n\n\n

\u201cWe can measure accuracy with automated tools,\u201d Erik added, \u201cbut there\u2019s no substitute for a native speaker saying, \u2018Yeah, that sounds right,\u2019 or \u2018Actually, this reads a little strange.\u2019\u201d<\/p>\n\n\n\n

Try Chinese, Japanese and Korean translation now built into Firefox<\/strong><\/h2>\n\n\n\n

CJK translation is already making a difference. Since launching support on desktop, Firefox has more than doubled active translation users in Asia. With Android support now rolling out in Firefox, even more people can experience the web in their language, safely and privately.<\/p>\n\n\n\n

Update to the latest version of Firefox for Android or desktop to start using CJK translation. Then, tap the translate icon when you visit a page in Chinese, Japanese or Korean. Firefox will do the rest, right on your device. For a list of all the translations available on Firefox, visit here<\/a>.<\/p>\n\n\n\n\n

\n \"\" <\/div>\n
\n

Take control of your internet<\/h3> Download Firefox<\/span> <\/div>\n<\/a>\n","protected":false},"excerpt":{"rendered":"

When Firefox users ask for better translation support, we make it happen. Thanks to your feedback on Mozilla Connect, Firefox now supports Chinese, Japanese, and Korean (often referred to as CJK) translation, both on desktop and Android. That means millions more people can browse and translate the web in their language, without sending their content […]<\/p>\n","protected":false},"author":1284,"featured_media":0,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[30,464325],"tags":[15889,464319,464204,4498],"coauthors":[311772],"acf":[],"yoast_head":"\nFirefox just got better for Chinese, Japanese and Korean speakers on Android<\/title>\n<meta name=\"description\" content=\"Firefox now supports Chinese, Japanese, and Korean (often referred to as CJK) translation, both on desktop and Android. 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