How to install SubSyncAI

What you need

• A computer with Windows 10 or Windows 11.
• Google Chrome or Microsoft Edge (the desktop versions). Other browsers are not supported.
• An internet connection during installation (Python, if it is missing, and the language packages are downloaded from the internet).
• About 10 minutes. You do not need administrator rights.
• Your license key from the email you received after purchase (you enter it in step 4).

1. Install the app

1. Download the installer

   Download SubSyncAI-Setup.exe from this website and save it, for example, in your Downloads folder.

2. Start the installer

   Double-click SubSyncAI-Setup.exe. If Windows shows a blue window “Windows protected your PC” (SmartScreen), click More info and then Run anyway. If your antivirus program asks, allow the file to run.

3. Follow the installation wizard

   The wizard speaks English or Slovenian (it follows your Windows language). Click Next. Leave the installation folder as it is: %LOCALAPPDATA%\Programs\SubSync AI. This is a folder of your own user account, which is why no administrator rights are needed.

4. Finish and start the first-time setup

   Click Install and wait. On the last page keep the box “Run the first-time setup now” ticked and click Finish. (If you unticked it by mistake: Start menu → SubSync AI → Repeat setup (Python environment).)

2. First-time setup (Python)

A small window appears with the text “Installing components (Python environment and packages)”. This takes one to two minutes. Please wait and do not close it.

1. If Python is missing: click “Yes”

   SubSyncAI needs the Python software package (version 3.9 or newer) in order to run. If Python is not on your computer, a question appears: “Do you want to download and install Python now?” Click Yes. The setup downloads the official installer from python.org (about 25 MB), checks its digital signature and installs Python only for your user account. “Add to PATH” is switched on automatically. Everything runs by itself — you do not need to click anything in the Python installer.

2. If you click “No”: install Python by hand

   Open https://www.python.org/downloads/, download Python and start its installer. In the first installer window tick “Add python.exe to PATH” at the bottom, and only then click Install Now. When it finishes, open the Start menu → SubSync AI → Repeat setup (Python environment).

3. Follow the setup wizard

   When the installation is done, the setup wizard opens: six short windows with Back and Next buttons that lead you through steps 3, 4 and 5 of this guide (pictures below). At that moment the browser (on its extensions page) and a Windows Explorer window (with the extension folder) have already opened by themselves — they are meant for the wizard’s windows 2 and 3. Simply follow the wizard; this page shows the same steps in more detail.

The setup wizard, window by window

This is what the six windows look like. The text in the windows is in English (in Slovenian if your Windows is Slovenian).

3. Add the browser extension (Chrome or Edge)

Where is the extension folder?

The folder is called extension and lies inside the SubSyncAI program folder. Its full path is:

%LOCALAPPDATA%\Programs\SubSync AI\extensionCopy

Easiest way to open it: press the Windows + R keys together, paste the path above into the small window and press Enter. The folder opens. It must contain manifest.json, background.js, content.js and a folder named adapters (see the picture). In the full form the path reads C:\Users\YOUR-USER-NAME\AppData\Local\Programs\SubSync AI\extension. AppData is a hidden folder — that is normal.

Folder not found? Right-click the Start SubSync AI icon on your desktop → Properties → Open File Location. A folder opens — the SubSyncAI program folder — and the extension folder is inside it. (An older installation may use a different program-folder name; the shortcut always leads to the right one.) At the end of the first-time setup, Windows Explorer also opens this folder by itself.

Note: in this picture the program folder still has an older name. Yours is called “SubSync AI”. What matters is the end of the path: …\extension.

Google Chrome

1. Open the extensions page

   Open Chrome. Click into the address bar at the very top of the window (where web addresses go), type the address below and press Enter. In the picture the address bar is framed in green.

   chrome://extensionsCopy

   Chrome did not open the extensions page?

   This happens often, and it is not your fault: websites are not allowed to open chrome:// pages with a link (Chrome blocks this for safety), so this guide cannot offer a clickable link — and the setup’s own attempt to open the page can fail, for example when another browser is your default or Chrome runs with a different profile. Do it by hand with one of these ways:

   • Type it yourself: click the address bar at the top of Chrome and type chrome://extensions (two slashes!), then Enter. Or use the Copy button above and paste with Ctrl + V.
   • Through the menu: click the three dots ⋮ at the top right of Chrome → Extensions → Manage extensions.
   • Through the puzzle icon: click the puzzle-piece icon next to the address bar → Manage extensions (at the bottom of the list).
   • It searched Google instead? Then you typed it into the page’s search box and not into the address bar. Click the very top bar of the window and try again.

2. Turn on “Developer mode”

   At the top right of the extensions page switch Developer mode on, so that the switch turns blue (right arrow in the picture). Three buttons then appear at the top left: Load unpacked, Pack extension and Update. If you do not see them, Developer mode is still off.

3. Click “Load unpacked”

   Click the button Load unpacked at the top left (left arrow in the picture). It loads an extension straight from a folder. A Windows window for selecting a folder opens.

4. Select the “extension” folder

   In that window click into the address bar at the top, paste the folder path (use the Copy button in “Where is the extension folder?” above) and press Enter. You are now inside the folder. Click Select Folder at the bottom right. Important: select the folder extension itself — the one that contains manifest.json — not the folder above it and not the adapters folder.

5. Check that it worked

   A card named SubSync AI (with a version number such as 0.3.2) appears in the list and its switch on the right is blue (turned on) — as in the picture. That is all: the extension is installed.

6. Pin the icon (recommended)

   Click the puzzle-piece icon next to the address bar and then the pin icon next to SubSync AI. The icon then always stays visible in the toolbar. Clicking it opens the subtitle appearance settings (font size and colors).

4. License and language settings

In the setup wizard, when you confirm the extension on its window 4 and click Next, the SubSyncAI tray app starts. Its icon appears near the clock at the bottom right of the screen (if you do not see it, click the small arrow ^ to show hidden icons), and the windows for the first settings open.

1. Enter your license key

   If no key is entered yet, the License window opens first. Copy the license key from the email you received after purchase, paste it into the field and click Activate. You should see “License activated successfully.”. This step needs an internet connection. Later you can reopen it: right-click the tray icon → License….

2. Open the Settings window

   The Settings window opens next (if it does not: right-click the tray icon → Settings (language, AI provider, model, key)...). The picture shows it in Slovenian; yours uses English or Slovenian, depending on your Windows.

3. Choose the two languages

   Translate from (source language) is the language of the original subtitles (for example English). Translate to (target language) is the language you want to read (for example Slovenian). The two languages must be different.

   Important: set the player’s subtitles to the “Translate from” language

   If you translate from English to Slovenian, the subtitles on Netflix or HBO Max must be set to English (not Slovenian and not Off). SubSyncAI translates the subtitles that the player is showing, so they must be in the same language as “Translate from”. The same applies to every other pair of languages.

4. Choose the translator

   Under AI provider choose Local translator (offline, free - no API key) to translate on your own computer for free — no API key needed and the subtitle text is not sent anywhere. Or choose an AI provider (OpenAI, Anthropic, Google Gemini or your own endpoint) and enter its API key; the costs of AI usage are then paid to that provider.

5. Download the language packages (local translator)

   Under the languages you see, for example, “Language packages: not downloaded yet (about 80 MB, 1 package(s))”. Click Download language packages (arrow in the picture). A confirmation window “Download language packages?” appears: read it, tick the check box and click Download. If you cannot see the window, look at the taskbar for a flashing icon or press Alt + Tab — the download starts only after you confirm. Wait until “Language packages downloaded.” appears (about 80 MB per package, downloaded only once). Translating between two languages that are not English goes through English, so two packages are needed.

6. Click “Save”

   Click Save. You should see “Settings saved.”. If you have not downloaded the language packages yet, the app warns you that translation will not work until you do. At the bottom of the window you can also choose the interface language (it applies after a restart).

5. Watch with translated subtitles

1. Check the tray icon

   The SubSyncAI icon near the clock shows the state: green = connected and ready, orange = translating right now, red = backend not reachable. Hold the mouse over it to read the status. If the icon is not there, start the app with the Start SubSync AI icon on your desktop or in the Start menu.

2. Open Netflix or HBO Max

   In the Chrome or Edge where you added the extension, open Netflix (page address netflix.com/watch/…) or HBO Max (play.hbomax.com/video/watch/…) and start a video. If the video page was already open before you added the extension, press F5 once to reload it.

3. Turn the subtitles on in the player

   In the player’s own subtitle menu turn the subtitles on and pick the language you set as “Translate from” (for example English). SubSyncAI then shows the translated subtitles over the picture.

   Important: set the player’s subtitles to the “Translate from” language

   If you translate from English to Slovenian, the subtitles on Netflix or HBO Max must be set to English (not Slovenian and not Off). SubSyncAI translates the subtitles that the player is showing, so they must be in the same language as “Translate from”. The same applies to every other pair of languages.

4. Change things later

   Languages, translator, API key: right-click the tray icon → Settings (language, AI provider, model, key).... Subtitle size and colors: click the SubSync AI icon in the browser toolbar. Closing the app: right-click the tray icon → Exit.

Problems? Troubleshooting

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