Why is folder export missing in my browser?
Direct folder writing depends on the File System Access API, which BatchMint expects mainly in Chromium desktop browsers. Use ZIP export in Firefox, Safari or restricted environments.
Last reviewed: July 23, 2026
Browser compatibility
BatchMint targets current Chrome, Edge, Firefox and Safari with local Worker, Canvas and WebAssembly processing. Direct folder export is mainly a Chromium desktop feature; ZIP is the fallback. Mobile uses one worker to reduce memory pressure.
The compatibility baseline
BatchMint needs a current browser with JavaScript, Web Workers, Canvas APIs, WebAssembly and Blob downloads. These capabilities are available in current Chrome, Edge, Firefox and Safari, but optional features such as direct folder export and PWA installation differ by browser and operating system. A page loading successfully is not enough: the selected codec and export route must also work on the actual device.
Browser and platform behavior
| Environment | Local processing | Folder export | ZIP download | Important note |
|---|---|---|---|---|
| Chrome desktop | Supported | Available after user permission | Supported | Best match for File System Access |
| Edge desktop | Supported | Available after user permission | Supported | Uses the same Chromium file-system path |
| Firefox desktop | Supported when required codec APIs are available | Not expected | Supported | Use ZIP when direct folder writing is unavailable |
| Safari desktop | Supported when required codec APIs are available | Not expected | Supported | Test large batches because memory behavior differs by device |
| Mobile browsers | Supported with one worker | Not relied upon | Supported subject to download behavior | Use small batches and keep the app in the foreground |
Why folder export is not shown everywhere
Direct folder export depends on the File System Access API and an explicit user permission. Chromium desktop browsers provide the intended route; Firefox and Safari use ZIP download instead. This is a planned fallback, not a processing failure. Browser privacy settings, private mode or administrator policy can also prevent a permission prompt even in a normally compatible browser.
Worker count and memory pressure
Desktop devices use no more than four local workers. Mobile uses one worker because a decoded image can occupy far more memory than its compressed file size. Several high-resolution photos in parallel can exhaust a phone or an older laptop even when the original files look small in a folder. The 20-image batch limit is a queue limit, not a promise that every device can hold twenty very large decoded images comfortably.
- Process one representative image before adding a large batch.
- Close other memory-heavy tabs if the browser reloads or cancels work.
- Avoid enlarging small sources and choose a useful maximum width.
- Split unusually large originals into smaller batches when the device becomes unstable.
PWA and offline use
The service worker caches the static application shell and codec assets after they have been requested. Installation prompts and home-screen behavior vary across browser and operating-system combinations. Offline processing is therefore a second-use capability: open the app online, use the required output format once so its codec is available, then test offline before depending on it during travel or field work.
Codec and format checks
JPEG, PNG and static WebP are accepted inputs in the current build. JPEG, PNG, WebP and AVIF are available as outputs, with AVIF loaded on demand. A browser may run the interface but still fail to initialize a codec because of an outdated WebAssembly implementation, restrictive content policy or corrupted cache. Refreshing the application and updating the browser are better first steps than repeatedly retrying the same batch.
A useful preflight test
- Choose one normal JPEG and one transparent PNG or WebP relevant to the job.
- Run the intended resize, watermark and output format.
- Open the result and check transparency, orientation, dimensions and filename.
- Test folder export if it is required; otherwise confirm ZIP download and extraction.
- Only after that test should the same recipe be applied to the rest of the batch.
Related compatibility references
- Supported image formats
Current input, output, transparency and format limitations.
- Privacy model
Which data stays local and which application assets still use the network.
- Open the BatchMint workspace
Run the preflight test on the device and browser that will process the batch.
FAQ
Why does mobile use only one worker?
Decoded image pixels consume much more memory than compressed files. One mobile worker reduces parallel memory pressure and the chance that the browser terminates the tab.
Will offline mode work the first time I open BatchMint?
Not reliably. The application shell and required codec assets need to be cached first. Test the intended output format online before relying on offline processing.