Kitsumi browser extension
Last updated: 28 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 word you hovered to the
  dictionary service (and, when you click the star to explain a line, that
  line and each of its words), 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.
• Fonts you download or add for subtitles, and word packs you download for
  Advanced scanning, also 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.

Subtitles you save from the subtitle timeline (the 📥 button, as .srt or plain
text) are handed to your browser as an ordinary download: a file on your
computer, which Kitsumi does not keep a copy of or send anywhere.


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:

Network access and data use

Kitsumi only contacts the services described below when you use the corresponding feature.

• Searching for subtitles on a listed site - Kitsumi contacts Jimaku, OpenSubtitles or SubDL, whichever service you have configured with your own API key. It sends the show title and page address, or the search terms you entered.
• Searching with a custom provider you added yourself - Kitsumi contacts only the site you added. Kitsumi does not choose, check or vouch for custom providers. It sends the title you search for, the language code, the ID of a result you open, and the key you provided for that site. It sends nothing else: no cookies, page address or referrer.
• Downloading a dictionary - Kitsumi contacts GitHub Releases, Hugging Face and the other hosts named in the dictionary catalog. Only a file request is made; no personal data is sent.
• Downloading a font in the Subs tab - Kitsumi contacts raw.githubusercontent.com, the Google Fonts repository on GitHub. It requests the selected font and its licence. No personal data is sent.
• Downloading a word pack for Advanced scanning in the Dict tab - Kitsumi contacts raw.githubusercontent.com, Kitsumi's own public repository on GitHub (Olexify/KitsumiOPS). It requests the selected pack. While a pack is installed, Kitsumi also requests the list of available pack versions (index.json) at most once a week when you open the Dict tab. No personal data is sent. Subtitle lines are split on your device and are never sent anywhere.
• Looking up a word online - This feature is off until you turn it on. Kitsumi contacts the dictionary services you select: Jisho, Jotoba, KRDict (with your own key), Wiktionary, freedictionaryapi.com, dictionaryapi.dev or MyMemory. It sends the word you looked up and forms of that word that Kitsumi works out in order to find its dictionary entry. These may include its dictionary form (食べていた → 食べる, 먹었어요 → 먹다), the word named by a “form of” definition, the spelling a Wiktionary page points to (准备 → 準備), words inside a compound for which no whole-word entry exists (楽園歴 → 楽園, 歴), words inside a stretch of kana read as one piece (はいもう → はい, もう), and a part of a word you hover in the popup (曇りなく → なく).
• Explaining a subtitle line - This feature is off until you turn online dictionaries on. Kitsumi contacts the dictionary services you selected, and MyMemory if you have selected it. Each word in the subtitle line is looked up as described above. The subtitle line itself, limited to 500 characters, is also sent to MyMemory when it is used for translation.
• Playing a word's pronunciation - Kitsumi contacts assets.languagepod101.com. It sends the word and its reading. Kitsumi fetches the recording once to check that a recording exists before playing it.
• Reading text from an image - For Japanese vertical text, Kitsumi does not contact any external service. For other languages, it contacts tessdata.projectnaptha.com and sends only the name of the language. The picture itself is recognised on your device and never leaves it.
• Generating subtitles with AI (optional) - Kitsumi contacts Groq. It sends the audio of the video or file you selected, together with your own Groq API key.
• AI definitions (optional) - Kitsumi contacts Groq. It sends the word and the subtitle line being processed, together with your own Groq API key.
• AI imagery (optional) - Kitsumi contacts WaveSpeed. It sends the prompt text, together with your own WaveSpeed API key.
• Mining a card to Anki - Kitsumi communicates with AnkiConnect at http://localhost:8765. It sends the card contents, including a screenshot or clip if you enabled those options. This request is made to AnkiConnect on your computer and never leaves your computer.

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.

Custom subtitle providers are yours, not Kitsumi's. In Settings, Subtitle
providers, you can add a subtitle site Kitsumi does not support (advanced). Kitsumi
shows three warnings first and adds nothing until you pass all three; it records on
your device when you accepted them. A custom provider only ever talks to the one
site you confirmed, and only over https; your key goes to that site and nowhere
else, and a request carrying it is never followed to another address. What comes
back is limited to titles, ids and file names as plain text, and subtitle files that
really are subtitles (anything else is refused, and web code in them is removed).
Everything that site receives or does is between you and it; see the licence.

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 word you hovered to the dictionary
  service you picked, because that is the only way it can look the word up.
  When you click the star on a subtitle to explain the whole line, each word of
  that line is looked up the same way, and the line itself goes to MyMemory for
  a translation - only if MyMemory is one of your online dictionaries.
• 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. When it loads a caption file or
  an image from the site you are on, your browser sends that site's own cookies
  with the request, as it does for the page itself.
• 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.