Privacy Policy

Kitsumi browser extension Last updated: 24 September 2026

Kitsumi has no accounts, no servers, and no analytics. Everything it stores, it stores in your own browser. It makes network requests only when you use a feature that needs one, and every one of those is listed below.

On a fresh install, nothing you type, hover, watch or listen to is sent anywhere. The features that would send something are off until you turn them on.

The Chrome Web Store asks every developer to tick which categories of user data their extension handles. Google defines handling as "collecting, transmitting, using, or sharing", and requires the declaration "even when data is processed or stored locally on a user's device and is not transmitted to external servers or third parties".

That is a much wider word than most people read into it. Reading the subtitle line on your screen in order to draw it back with a dictionary attached is handling, even though the line never goes anywhere. Kitsumi ticks the categories honestly rather than picking the flattering reading, so here is what each one actually is:

• Website content. The subtitle text on the page, read so the overlay can be drawn and so you can hover a word. That reading happens on your device. Two optional features then send a piece of it onward, and only the piece you asked about: online dictionary lookups send the single word you hovered to the dictionary service, and the AI features send the subtitle line, or the audio of the video, to the provider whose key you entered. Both are off until you switch them on, and both go to those services rather than to anything of Kitsumi's.
• Authentication information. The API keys you choose to type in, for Jimaku, OpenSubtitles, SubDL, Groq or WaveSpeed. They sit in your browser and go only to the service that issued them.
• Web browsing activity. The title and address of the tab you are watching, used to work out which show it is, and remembered per show so the next episode finds its subtitles. It is sent to a subtitle provider only on the sites you have put on your list, and only after you have accepted the providers notice inside the extension (see below).

None of it reaches the developer, because there is nowhere for it to go. Kitsumi has no server, no account, no analytics and no telemetry. Those categories describe what the software touches on your machine, not what anybody collects about you. Everything below sets out exactly where each thing goes.

All of the following is kept locally in your browser, using extension storage and IndexedDB. None of it is transmitted anywhere.

• Your settings: subtitle appearance, position, timing offsets, per-show sync offsets, interface preferences, allowlisted sites.
• Your study data: words you have looked up, words marked as known, study time, streaks, active days, ranks and achievements, per-language statistics.
• Dictionaries you install, stored as local databases.
• Subtitle files you load, for the duration of playback.
• Recognition data for any OCR language you have used, cached after its first download.
• API keys you choose to enter for optional third-party services.

You can delete all of it at any time by removing the extension, or by using the reset controls in the extension's settings.

Kitsumi does not contact any server operated by the developer, because none exists. It contacts third-party services only in response to an action you take:

Online dictionary lookups are off on a fresh install. Until you switch them on, every lookup is answered from the dictionaries stored on your device, with no network request at all. You can turn them on in the popup, from the Dict tab or the switch on its main screen; the first time, Kitsumi shows a short notice saying exactly what is sent and to whom, and nothing is sent before you accept it. Turning every source off again switches them back off.

Subtitle providers need a key of your own. Kitsumi ships no shared key. Jimaku, OpenSubtitles and SubDL each stay dormant until you enter one, so none of them is contacted until you decide to set it up.

Subtitle providers are asked only on sites you list. The automatic search (in the background, and the one that runs when you open Kitsumi) is built from the page's title and address, so it runs only on the sites you have added to your list in the extension. On every other site nothing is sent to any provider. The first time you enable a provider, turn on the background search, or search by hand, Kitsumi shows a short notice saying exactly this and asks you to accept it; nothing is sent to a provider before you do. Declining switches the providers off again. Your list stays empty until you accept the notice, and YouTube is never on it: there Kitsumi uses YouTube's own subtitle tracks and asks no provider. Kitsumi never reads anything you type into a page - no passwords, no forms, no messages - on any site, listed or not.

The AI features are off by default and stay dormant until you enter your own API key. With no key present, no request is made to Groq or WaveSpeed at any time.

About the OCR download. Japanese vertical recognition works entirely offline; its data ships inside the extension. Any other language downloads its recognition data once, from tessdata.projectnaptha.com, and keeps it on your device afterwards. The only thing sent is the name of the language. In the Opera version of Kitsumi this also applies to Japanese, because Opera's store does not accept that file type in a package. What is downloaded is recognition data, not program code, and none of your images or text is uploaded for it.

Each third-party service handles the data it receives under its own privacy policy. If you enable one of these features, you are choosing to send that content to that provider, under your own account where a key is involved.

Kitsumi requests access to all sites because subtitles have to be rendered over video players it cannot know about in advance, including players inside embedded frames. It reads the page only to find the video player and its subtitle track, the word under your cursor on a site where you turned the article reader on (it runs only on sites you add yourself), and any image you point the OCR at.

Reading the page is how the overlay gets drawn, and it is why the store listing declares website content. What Kitsumi does not do is keep any of it or send it away. Page content is read, used to render the thing you are looking at, and discarded; nothing about the pages you visit is stored beyond the show title Kitsumi remembers so the next episode finds its subtitles.

There are two exceptions, both entirely in your hands and both off until you switch them on:

• Online dictionary lookups send the single word you hovered to the dictionary service you picked, because that is the only way it can look the word up.
• The AI features send the subtitle line, or the audio of the video you asked to transcribe, to the provider whose API key you entered.

Nothing else from the page is ever transmitted, and none of it is ever stored outside your browser.

If you would rather narrow this, both browsers let you restrict an extension to specific sites:

• Chrome: right-click the extension icon, "This can read and change site data", "On specific sites".
• Firefox: Add-ons Manager, Kitsumi, Permissions.

All features continue to work on the sites you allow.

• No user accounts, sign-in, or registration.
• No analytics, telemetry, crash reporting, or usage tracking.
• No advertising and no advertising identifiers.
• No cookies. Kitsumi neither sets nor reads any.
• No selling or sharing of data.
• No transmission of your study history, vocabulary, or statistics anywhere.
• No sending of your API keys to anyone but the service that issued them.
• No reading of what you type into pages: passwords, forms and messages are never read, on any site.
• No contacting a subtitle provider on a site you have not listed, or before you have accepted the providers notice.

Kitsumi is a general-purpose study tool and does not knowingly collect data from anyone, including children.

Material changes to this policy will be published at kitsumi.org/privacy and in the project's repository, and its "last updated" date will change. The version history is public in the repository.

Questions about this policy: olexifyyy@gmail.com Or ask in the Discord.