Data management

Back up your progress, understand localStorage structure, and reset your KAnki data when needed

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.

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/.

What data is saved

KAnki persists the following information between sessions:

Deck data

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

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

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
}

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.

Resetting data

KAnki provides two reset options:

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

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

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.

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.