Privacy Policy

StemStudio ("the Service") is a web application that processes files entirely inside your browser — audio separation among them. This privacy policy describes how privacy is handled when you use the Service.

The Service never sends the files you choose to any server. That applies to every file type its tools handle — audio, images, video, PDFs, text. All processing happens in your browser, results are generated in-browser, and they are saved to your device only when you explicitly choose to download them. Neither the contents nor the filenames are transmitted.

The Service may use your browser’s localStorage to remember preferences and stability information (such as whether WebGPU finished cleanly last time). Once an AI model has been downloaded, it is also stored in your browser’s Cache Storage so that later runs do not have to download it again. Each model is roughly 20–260 MB, and using several of them can add up to more than 1 GB. All of this is kept only on your own device and is never transmitted anywhere. You can see how much is stored and delete it from the "Data stored on your device" panel at the bottom of this page, or by clearing this site’s data in your browser settings.

The Service carries advertising from third-party vendors, including Google AdSense. Third-party vendors, Google included, use cookies to serve ads based on your prior visits to this Service and to other websites. No personally identifiable information is collected in the process. You may opt out of personalised advertising from Google through Google Ads Settings, and out of personalised advertising from other third-party vendors through aboutads.info. Opting out does not remove advertising — the ads simply stop being based on your browsing history.

• Google Ads Settings (turn off personalised ads)
• aboutads.info (third-party vendor opt-out)
• Google Privacy Policy

For visitors in the European Economic Area, the United Kingdom and Switzerland, cookies for advertising and analytics are not used until you consent. A consent dialogue appears on your first visit and the Service behaves according to the choice you make there. You can change or withdraw consent at any time. The dialogue is provided by a Google-certified consent management platform.

• How Google uses cookies in advertising

The Service may include affiliate links to third-party products and services. If you buy or sign up through such a link, the operator of the Service may receive a referral commission from the vendor. These links are always shown with a clear sponsorship label, and using them never increases the price you pay. Inclusion reflects the operator’s own judgement and is not a warranty of quality or safety. Terms of sale and handling of personal data on the linked site are governed by that provider’s own terms and privacy policy.

The Service uses Google Analytics 4 to understand how the site is used. Via cookies provided by Google, statistical information is collected and sent to Google: which pages were viewed, where visitors came from, and which features were used (which model a separation started or finished with, whether a download happened, and so on). It never includes your audio file, its filename, or anything derived from the audio itself — your audio does not leave the Service. Even track length is recorded only as a bucket such as "1-3m" rather than an exact duration. If you would rather not allow these cookies, you can disable them in your browser settings or with Google’s opt-out add-on. Separately, Vercel Web Analytics — provided by the host this site runs on — records the page URL, the referrer, a coarse region and the device type. It sets no cookies and stores no identifier that could single you out. For details, see:

• Google Privacy Policy
• Google Analytics opt-out browser add-on

A few tools need to talk to the outside world to do their job. DNS Lookup sends the domain you type to Cloudflare’s public DNS (cloudflare-dns.com). The speed test exchanges filler data with Cloudflare (speed.cloudflare.com). The weather and earthquake tools read open data from the Japan Meteorological Agency (www.jma.go.jp / www.data.jma.go.jp); only which region or list you viewed is sent. The IP address check uses an endpoint on this site’s own domain (/api/ip), and the address it receives is used to build the response and not stored. Device-to-device transfer passes only the information needed to open a connection (SDP and ICE candidates) through this site’s signalling server — the file itself goes straight between the two devices. Separately, AI separation models may be fetched from Hugging Face and fonts from Google Fonts. None of these requests carries a file you gave a tool, or its name. The full list of destinations, and what triggers each one, is on the data handling page.

• Data handling — every destination we contact

The Service may link to external websites. Please review the privacy policies of those sites individually. We are not responsible for the content or privacy practices of external sites.

This privacy policy may change without prior notice as the Service improves or as laws change. The revised policy takes effect once posted on the Service.

You are responsible for using the Service only with audio you own the rights to, or are permitted to use. You are responsible for complying with applicable laws and treaties regarding the separation and redistribution of copyrighted audio.

For questions about this privacy policy, please contact us at the address below.

Email: privacy@stemstudio.jp