Privacy Policy

Last updated: 11 October 2026

Kobutai is an open-source browser extension. The developer runs no servers and does not collect, receive or sell any user data. The extension has no analytics, tracking or ads.

What the extension reads and stores in your browser

DataWhyWhere it lives
The media that is playing: title, artist, cover URL, position, volume, site domainShow the control bar, control playback across tabs, tag the contentMemory only; gone when the tab closes
Overlay position and size (per site), sites where the character is hidden, interface language, the name you sign shared characters withRemember your settingschrome.storage.local (this device)
Your album (which characters you've drawn and how often), tag cache (content → type/genre)Draws and the albumchrome.storage.local (this device)
Locked character IDSync between browsers signed in to the same Google accountchrome.storage.sync (synced by Chrome; the developer can't see it)
The current draw, the characters for the last 50 items played (title/artist/domain), which media is primaryRestore after the background restarts; bring back the same character when you return to somethingchrome.storage.session (cleared when the browser closes)
Characters you import or downloadShow the charactersThe extension's own IndexedDB (this device)
With “auto-match characters” on: the part of the Petdex list the match table uses (names and asset URLs), auto-downloaded characters and when they were last usedFind and keep matched characterschrome.storage.local and IndexedDB (this device)
API keys, subscription sign-in tokens (OAuth), custom model endpoints and the chosen modelOptional AI taggingchrome.storage.local (this device, not synced)

The extension does not read page text, forms, cookies or your browsing history, and never sends full page URLs to anyone.

When it goes online, and to whom

Network requests happen only in these cases, and always straight from your browser:

  1. AI tagging (off by default). Only if you connect your own model provider on the “AI” page (API key, subscription sign-in or custom endpoint) and turn it on. What's playing is recognised by a small model built into the extension, on your device, and nothing is sent. Only for a new item the built-in model is unsure about are its title, artist and site domain sent to the provider you chose (for example OpenAI, Anthropic, DeepSeek, OpenRouter, or your own Ollama server) to work out the type and genre. That provider's privacy policy applies. Results are cached on your device, so the same item is never sent twice.
    • When connecting: subscription sign-in opens the provider's sign-in page and exchanges tokens with its authorisation server; expired tokens are refreshed with that provider automatically.
  2. Remote character library. Every 12 hours (30 minutes after a failure) the extension downloads characters from the libraries you subscribe to (by default the project's GitHub repository library/ folder on raw.githubusercontent.com). A library's pack.json may point to assets on other https addresses, which are then fetched too. No personal data is sent, but those servers see your IP address, as with any website.
  3. Petdex import. Only when you search or import on the settings page: the extension fetches the pet list from assets.petdex.dev, then downloads the assets of the pet you picked from the https addresses in that list.
  4. Cover art. The control bar shows the cover image provided by the site that is playing (https only). Your browser loads it from that image's server, without a Referer.
  5. Auto-match characters (off by default). Only when you turn it on. The extension checks the title and artist against a built-in rule table on your device; titles and artists are never sent anywhere. On a match with a character that hasn't been downloaded yet, it fetches the pet list from assets.petdex.dev (at most once a day) and that one character's assets. No personal data is sent, but Petdex's servers see your IP address and which character was downloaded, from which they could roughly infer that you're playing something related to it. Characters already downloaded don't trigger any request.

The built-in characters and the emoji used in bubbles ship inside the extension; showing them doesn't go online.

Sharing a character you drew sends nothing by itself: the extension saves a zip to your Downloads folder and, if you click, opens a GitHub page or your email app. You decide whether to send the file. If it's accepted, its name, your credit name and the sprite sheet are published in the project's GitHub repository under CC BY 4.0.

Permissions

Deleting your data

Removing the extension at chrome://extensions deletes everything it stored. You can also clear the tag cache and delete imported characters from the settings pages.

Contact

Questions and suggestions are welcome as GitHub issues: github.com/xingaobio/kobutai