Image Format Converter (JPG/PNG/WebP/AVIF + Base64)

Image Format Converter: Format Conversion and Two-Way Base64 Conversion

Different platforms have different image format requirements. Some accept only JPG, some prefer WebP for smaller file sizes, some require PNG to preserve transparency, and frontend development often requires images to be converted to Base64 for direct inclusion in code. This tool combines format conversion and two-way Base64 conversion in two tabs on the same page. All processing happens locally in the browser, and images are never uploaded to a server.

Supported Input and Output Formats

Input supports six common formats: JPG, PNG, WebP, AVIF, GIF, and BMP. Output supports JPG, PNG, WebP, and AVIF. Common conversion directions are covered, including JPG and PNG conversion, JPG and WebP conversion, PNG and WebP conversion, and WebP and AVIF conversion. You can also use Auto (preserve original format) to re-encode an image. GIF and BMP are input-only because browsers cannot directly export them in all cases. In Auto mode, they are output as PNG. Animated GIFs use only the first frame; use a specialized tool when animation needs to be preserved.

Output Quality and Transparent Backgrounds

When outputting JPG, WebP, or AVIF, the quality slider controls compression strength. Lower values produce smaller files, and image-quality loss is generally difficult to notice between 75 and 90. When outputting PNG, the quality option is automatically disabled because PNG is lossless. Transparency can be handled in two ways: select Preserve transparency to retain transparent areas in PNG, WebP, and AVIF, or select Use background color to fill them with a chosen color. Because JPG does not support transparency, JPG output automatically uses background-color filling, with white as the default, preventing transparent areas from becoming black.

Batch Conversion and ZIP Downloads

You can drop multiple images at once. The list shows filenames, original formats, file sizes, and pixel dimensions, with individual removal supported. After clicking Convert, images are processed sequentially. A progress bar shows the current progress, and processing can be cancelled. With one image, the page displays a before-and-after comparison and percentage size change. With multiple images, it switches to a table showing filename, original size, converted size, change percentage, and download buttons. Download All (ZIP) packages the results at once. Filenames are preserved while extensions are automatically replaced according to the output format.

Image to Base64

On the Image to Base64 tab, select an image and choose between Data URL, which includes the data:image/png;base64 prefix and can be used directly as the src of an img tag or as a CSS background-image, and raw Base64, which contains only the encoded content and is suitable for API parameters or configuration files. The result displays character count, original file size, and detected format, with one-click copying and text-file export. For very long content, only the beginning is displayed on the page, while copying and exporting always use the complete content to avoid slowing down the page.

Base64 to Image

On the Base64 to Image tab, paste a Data URL or raw Base64 string to restore an image. The tool automatically detects the prefix, handles line breaks and URL-safe characters (converting hyphens and underscores back to plus signs and slashes), and adds missing padding when needed. If there is no Data URL prefix, the tool inspects the decoded bytes to determine the actual format, so raw Base64 can still be correctly identified as PNG or JPG. After restoration, it provides a preview, detected format, and file size, and the image can be downloaded with the appropriate extension. Clear errors are shown when the content is not an image, contains invalid characters, or exceeds the size limit.

Frequently Asked Questions and Error Handling

Can WebP be converted back to JPG?Yes. Use WebP as the input and select JPG as the output. However, each lossy conversion accumulates quality loss, so converting from the original image is recommended.
What happens to transparent backgrounds when PNG is converted to JPG?They are filled with white by default. You can also select Use background color and specify any color before conversion.
Does Base64 increase file size?Yes. Base64-encoded text is approximately 1.37 times the size of the original file. It is suitable for embedding small icons but is not recommended for large images.
What happens to duplicate or non-image files?Duplicate files are skipped with a notification, while non-image or unsupported files receive a specific explanation.
What if the browser does not support an output format?For example, some browsers cannot export AVIF. In that case, the option is automatically disabled and the page explains the reason.

Privacy and Data Security

There is no upload interface. Format conversion, quality adjustment, and Base64 encoding and decoding are all performed in the browser. Images are not sent to a server or saved, and they are released from memory after the page is refreshed or closed. To control memory usage, batch conversion processes images sequentially and releases each bitmap resource immediately after processing. Base64 encoding and decoding have size limits, and oversized content is rejected with a clear message instead of causing the page to freeze.