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Jengo

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Jengo

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Jengo

Why Jengo?

If you want to learn a language, you have to study. The problem is how. Most options fall into two extremes: memorizing thousands of flashcards out of context, or passively consuming native content with little retention. Both are inefficient.

You're not rewarded for doing the right thing at the wrong time.

Jengo fixes that.

Jengo uses a spaced repetition learning system powered by an algorithm that predicts when you're about to forget something and attempts to display it to you at the exact right moment. Words appear through generated prompts, always in context. Everything is optimized: the right thing, at the right time.

Best way to use Jengo:

  • Read, watch, and consume normal content
  • Add words you don't know — Jengo will make sure you see them again
  • Use it every day (consistency beats intensity)

As you improve, you'll often encounter new words and think: "Is remembering this even worth it? When am I ever going to see this word again?" With Jengo, it's worth it.

Happy studying – JengoDev

How to Use Jengo

1
Add wordsAdd words manually by going to the Words tab or by pressing the blue plus in the bottom right. You can also open the Config menu and go to Import Decks to upload a file, or import a pre-made JLPT deck of words (N5–N1).
2
Configure your settingsGo to Study Config in the settings menu — or press the config button next to the Start button — to set your generation preferences before you start.
3
Press "Study"Jengo generates a Japanese paragraph using your due words. If you have a lot of words, you will need to read and submit multiple times.
4
Select unknown wordsTap vocabulary you don't understand to see the definition. On mobile, you can press the orange dictionary in the bottom right to see the definition.
5
SubmitWhen you've finished reading, submit the paragraph. Mark ALL words you don't understand before submitting. The algorithm schedules each word for the right time based on your feedback. You can see how well the algorithm is performing in the Statistics tab. Repeat until you've reviewed all scheduled words, then come back tomorrow!

Profile

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Beta Features
Enables Read, Encounter, and Listening modes

Study

Reading Settings

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Listening Settings

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Languages

Decks

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File format guide

.txt — one word per line

食べる
飲む
走る

.csv — lemma column required; surface and pos optional. Without a header, first column is used as lemma.

lemma,surface,pos
食べる,食べ,動詞

.json — array of strings or objects with a lemma key

["食べる", "飲む"]
// or
[{"lemma": "食べる", "surface": "食べ", "pos": "動詞"}]

All files must be UTF-8 encoded. Only lemma is required.

Manage your word database in the Words tab.

Learning Algorithm

The probability you'll remember a word when it comes up for review. 0.90 is the recommended default — it's the value the scheduling algorithm is calibrated around, and it balances review workload with solid retention. Lower values (e.g. 0.80) space out reviews more but you'll forget more often; higher values (e.g. 0.95) keep retention very high but can significantly increase daily reviews.

Runs coordinate-descent optimization on your review history to improve scheduling accuracy.

Last tuned: –

Review Log
IDLemmaTimestampRating

Appearance & Haptics

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Show all tips again

Notifications

Notifications are scheduled each time you open the app.

Daily Reminder Reminds you to study each day.
Remind me at
Streak Saver Late reminder if you haven't studied yet.
Remind me at
Streak Milestones Celebrate streaks at 3, 7, 14, 30, 100, and 365 days.
Tap a word to look it up

    Your Vocabulary

    – Total Words
    – New Available
    – Due Today
    – Future Scheduled

    Young = reviewed, interval under 21 days  ·  Mature = 21+ day interval

    Upcoming Workload

    Overdue Scheduled

    Activity

    – Day Streak
    – Reviews Today
    – Total Reviews

    True Retention

    The share of due reviews you actually recalled, measured from your history. Mature cards (21+ day interval) are the truest signal — aim for them to sit near your target.

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