Private Subtitle Generator: How to Check It Yourself
Most online subtitle tools upload your file to a server. This one does not. Here is how the AI runs on your device, and how you can confirm it with your own eyes.
The AI model comes to you
The first time you generate subtitles, your browser downloads an open speech-recognition model once. It is stored in your browser, so later runs do not download it again.
Your file is read locally
Your browser reads the audio from the file on your device. The file itself is never sent to a server.
The model runs in your browser
Speech recognition runs on your device’s processor in a background process of the page. That is why long files take as long as your device needs.
Verify it yourself
Open your browser’s developer tools, choose the Network tab, then generate subtitles. You will see the model download the first time, but no request that carries your video or audio.
Why privacy matters for subtitles
The recordings people subtitle are often personal or sensitive: a job interview, a lesson with students, a client call, a family video, a product that has not launched yet. When a tool uploads that file to a server, you are trusting a company with something you might not want anyone else to hear, and you rarely know how long it is kept or who can access it.
A subtitle generator that runs in your browser changes the equation. The audio is read on your device, the AI works on your device and the text appears on your device. There is no copy of your recording sitting somewhere else.
What actually happens on your device
- You choose a file. The browser opens it directly from your disk and never sends it anywhere.
- The page loads an AI model the first time, from a public model host, and stores it in your browser’s cache.
- Your audio is decoded and processed in a background worker inside the page, so the interface stays responsive while it works.
- The subtitles appear in the editor. When you click download, the file is created in your browser and saved to your computer.
The only thing that travels over the internet is the model itself, and that happens once.
How to check it yourself in two minutes
- Open the tool and press F12 (or right-click and choose Inspect), then open the Network tab.
- Clear the list so you start from a clean view, then drop in a short video and press generate.
- Watch the requests: you will see the model files download the first time, and nothing that carries your video.
- Run it a second time. Now the model is cached, so almost nothing new appears at all.
Look at the size of each request too: the model files are large, while nothing close to the size of your video is ever sent out.
What this means for your projects
For public videos, privacy is a nice extra. For anything else, it can be the deciding factor: you can subtitle an interview before it is released, caption a lecture with student voices, or prepare client work without sending it to a third party.
It also helps with speed, because there is no upload to wait for. If you are comparing tools, privacy is one of the checks in our guide on choosing the best free subtitle generator, and you can read the full policy on our privacy page.
Quick tips
- Clear this site’s data in your browser settings to delete the downloaded model.
- Close the tab and the page forgets the file; only the subtitles you downloaded remain.
- Read the privacy policy for the full list of services involved.
Ready to try it? Drop a video or audio file into the free subtitle generator and have subtitles in minutes. Open the generator →