ByteScope

Batch Image Converter

Batch convert entire folders of images between formats — locally, with zero uploads.

The folder is opened locally by your browser. Images are converted and saved directly to your disk — nothing is uploaded, and your files never leave this tab.

Folder

Choose a folder containing images to convert in batch.

folder
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files
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Which files

File types in this folder

  • Nothing to show yet.

Target format

Output mode

JPEG cannot store transparency. Transparent pixels are filled with white before encoding — without that they come out black.

Converting re-encodes the pixels, so EXIF, GPS and camera notes in the original do not carry into the converted file. JPEG and PNG output is additionally passed through the same stripper /remove-exif uses; the colour profile is kept so the picture still looks right.

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Browser support

Renaming and deleting files where they sit needs the File System Access API, which only Chromium browsers ship. Everything below happens on your machine either way — nothing is ever uploaded.

capabilityChromeEdgeFirefoxSafari
Open a folder from diskwindow.showDirectoryPicker — Chrome/Edge 86 and later, desktop only✓supported✓supported✗not supported✗not supported
Rename a file in placeFileSystemFileHandle.move — Chrome/Edge 111 and later✓supported✓supported✗not supported✗not supported
Delete a file in placeFileSystemDirectoryHandle.removeEntry✓supported✓supported✗not supported✗not supported
Remember the folder for next timethe handle is kept in IndexedDB on this device; permission is asked again✓supported✓supported✗not supported✗not supported

detected in this browser

  • window.showDirectoryPicker …
  • FileSystemFileHandle.move …
  • indexedDB …

On Firefox or Safari, or on any phone or tablet, this page can explain the job but cannot do it. Open it on desktop Chrome or Edge.

About this tool

Batch Image Converter lets you select an entire folder of images on your computer and convert them all between JPG, PNG, WebP, and AVIF in one go. Using the browser's native File System Access API, images are read and written directly on your local disk without uploading a single byte to any remote server.

Choose target formats, tune compression quality or specify a target file size, and optionally fill transparent backgrounds with white when converting to JPG. Re-encoding does not preserve metadata such as EXIF, which is explicitly stripped. You can save converted images alongside the originals, output them to a dedicated subfolder, or replace the original files after explicit confirmation. Subfolder recursion is supported with real-time progress and per-file error reporting.

Frequently asked questions

Are my images uploaded to any server?

No. All conversions run entirely inside your browser using WebAssembly codecs. Your images never leave your computer.

Which image formats are supported?

The tool supports reading and converting between JPG/JPEG, PNG, WebP, and AVIF images.

What output options are available?

You can save converted files alongside original images, output them into a newly created subfolder, or overwrite the original files after a confirmation warning.

Can it process subfolders recursively?

Yes. When subfolder recursion is enabled, all nested folders are traversed and images are processed while preserving relative folder structures.

What happens if a single image fails to convert?

The batch continues processing remaining images without interruption. A detailed failure summary table lists any skipped or failed files along with the error reason.