How much can it reduce the size?

Typical savings are 30–70% depending on the original quality and chosen settings. The tool uses the browser's Canvas with good JPEG and WebP encoders.

Does it support transparency?

Yes for PNG and WebP output. For JPEG output the background is filled with white because the JPEG format does not support transparency.

Is my image data private?

Everything is processed locally in your browser using the Canvas API. No data is uploaded or stored.

Can I paste just the raw base64 without a data URI prefix?

Yes. The tool auto-detects the image format from the magic bytes in the decoded data. Both raw base64 and full data URIs are accepted.

Why is my Base64 image so large?

Base64 encoding adds about 33% overhead to the binary size, and PNG screenshots are often already large. Converting to WebP or JPEG and reducing the dimensions is usually the fastest way to shrink the string.

Is Base64 a good way to embed images in HTML?

Only for very small images. Base64 bloats the HTML, prevents separate caching, and blocks rendering until the CSS or HTML finishes loading. Use it for one-off icons and tiny assets — for everything else, use a real image file with proper caching headers.

Base64 Image Optimizer

Paste or upload a Base64 image and get back a smaller one. Control output format, maximum width and height, and quality — the tool re-encodes the image through the Canvas API. Handy for shrinking inline data URIs in HTML, CSS or JSON payloads.

How to use

Paste or upload the Base64 image

Paste a data URI or raw Base64, or upload a file.

Set output options

Choose format, max width, max height and quality.

Click Optimize

The tool re-encodes the image with the chosen settings.

Copy the result

Copy the optimized Base64 or data URI to your clipboard.

Output format

Max width

Max height

Quality80%

Everything runs in your browser. Your image data never leaves your device.

Base64 input

Upload file

Optimized base64

Features

Format conversion

Convert between PNG, JPEG, WebP, GIF, BMP and AVIF (output limited by browser support).

Resize and compress

Control max width, max height and quality to shrink the encoded string.

Size comparison

See original and optimized size side by side.

Auto-format detection

Detects the input format from the data URI or magic bytes.

Common use cases

Shrink a Base64 image embedded in HTML
Compress a data URI before adding it to a CSS file
Resize an inline base64 image for an email template
Convert a large Base64 PNG to a smaller WebP

Frequently Asked Questions

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