Jiten is a free and open-source platform for Japanaese learning through immersion. The text of thousands of anime, dramas, novels, manga, visual novels and other media type is analysed and transformed into data you can use to study: a complete vocabulary list, an estimation of the difficulty, a length through the character count. You can study the vocabulary directly on the site in-built SRS with powerful filters to help you choose exactly the words you need, and also download then as an Anki deck. By tracking your knowledge on Jiten, you will be able to see your coverage on every title, that is how much of it you will understand before even starting.
The core idea being Jiten is pretty simple: pick something you want to read or watch, helped by the filters and difficulty rating, then learn the words you will encounter right before immersing in it. The what is Jiten guide will give you a good overview of that method, and the features page lists the numerous other features of the website.
Jiten is built and run by a solo developer, Sirus. The full source code is available on GitHub under the Apache 2.0 licence, and the main community lives on Discord, where feature requests, bug reports and media requests get discussed daily. You can find formal company details in the legal notice.
Dictionary data comes from JMdict, JMnedict and KANJIDIC, property of the Electronic Dictionary Research and Development Group and used under its licence. The media metadata (covers, titles, descriptions, release dates, ...) comes from sources such as AniList, VNDB, TMDB, IGDB and Google Books. They are fully listed in the data sources guide.
Audio pronunciations are generated using VOICEVOX with the voices 四国めたん (Female 1), 九州そら (Female 2, ASMR), 剣崎雌雄 (Male 1) and 青山龍星 (Male 2).
Every data derived by Jiten from that analysis including the decks, frequency lists and statistics, is published under CC BY-SA 4.0. You can use them in your own projects as long as you respect the licensing guide and the API terms.
Jiten has a fully-fledged core toolset that's continuously being expanded, including: the media library, coverage, deck downloads, the SRS, the various extensions, the statistics, and many more features. There is an optional subscription model in the form of Jiten+ with a few premium features, as well as donations. There are no ads, and your data is never sold. You can find all the details in the privacy policy.
Email contact@jiten.moe, join the Discord server, or open an issue on GitHub.