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KAnki automatically saves all study progress and card statistics to your Kindle’s local storage. Understanding how this data is stored helps you back up progress and troubleshoot issues.

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localStorage location

All your study data is stored in your Kindle’s localStorage at this path: 
/Kindle/.active_content_sandbox/kanki/resource/LocalStorage/file__0.localstorage
This file contains all your card statistics, review history, difficulty ratings, and timestamps. Your deck configuration (kanki_config.js) is stored separately in /documents/kanki/js/.

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What data is saved

KAnki persists the following information between sessions:

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Deck data

{
  cards: [],
  lastStudied: <timestamp>,
  name: "Language Flashcards"
}

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Card statistics

Each card tracks:
  • Difficulty level: 0-5+ based on spaced repetition algorithm
  • Next review time: Calculated timestamp for when card is due
  • Review history: Array of all attempts with timestamps and results
  • Starred status: Whether the card is marked as important
  • Times viewed: Count of how many times you’ve seen the card
  • Last viewed: Timestamp of most recent view

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Example card data structure

{
  front: "hello (konnichiwa)",
  back: "こんにちは",
  notes: "Greeting",
  level: "N5",
  difficulty: 3,
  nextReview: 1709467200000,
  history: [
    {date: 1709380800000, result: true, difficulty: 'good'},
    {date: 1709294400000, result: false}
  ],
  starred: true,
  timesViewed: 5,
  lastViewed: 1709467200000
}

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Backing up your progress

To preserve your study progress before updating KAnki or changing decks:
1

Connect your Kindle

Plug your Kindle into your computer via USB.
2

Navigate to localStorage

Browse to:
/Kindle/.active_content_sandbox/kanki/resource/LocalStorage/
The .active_content_sandbox folder may be hidden. Enable “Show hidden files” in your file manager.
3

Copy the file

Make a copy of file__0.localstorage to your computer for safekeeping.
4

Restore if needed

If you need to restore your progress, copy the backed-up file back to the original location, replacing the existing file.

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Resetting data

KAnki provides two reset options:

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Reset progress only

Resets all card statistics while keeping your deck intact:
  1. Open KAnki on your Kindle
  2. Access the settings menu (3 dots in top bar)
  3. Select “Reset Progress”
  4. Confirm the action
This resets:
  • All difficulty levels to 0
  • All review times to current time
  • Review history
  • View counts
  • Starred status is preserved

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Reset all data

Returns to the default deck and clears all progress:
  1. Open KAnki settings
  2. Select “Reset All”
  3. Confirm the action
This:
  • Loads the default deck from kanki_config.js
  • Clears all progress and statistics
  • Removes all starred cards
  • Resets level and filter preferences

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Manual reset

Alternatively, you can manually delete the localStorage file:
1

Connect Kindle to computer

Use USB connection to access the filesystem.
2

Delete localStorage file

Remove:
/Kindle/.active_content_sandbox/kanki/resource/LocalStorage/file__0.localstorage
3

Restart KAnki

Launch KAnki on your Kindle. It will create a fresh localStorage file with the default deck.
Manual deletion completely removes all data with no undo option. Always back up first if you might want to restore your progress later.

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Updating KAnki with existing data

When updating to a new KAnki version:
1

Back up your files

Save copies of:
  • kanki/js/kanki_config.js (your deck)
  • /Kindle/.active_content_sandbox/kanki/resource/LocalStorage/file__0.localstorage (your progress)
2

Replace KAnki folder

Download the new version and replace the old /documents/kanki/ folder.
3

Restore your deck

Copy your backed-up kanki_config.js to the new:
/documents/kanki/js/kanki_config.js
4

Copy font file

Transfer your language.ttf font to:
/documents/kanki/assets/fonts/language.ttf
5

Launch and reload

Open KAnki and click the reload button (3 dots → Reload) to apply changes.
Your localStorage file usually remains intact during updates since it’s stored in a separate system directory. However, backing it up is still recommended for safety.

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