Is my image uploaded to a server?

No. Encoding uses FileReader.readAsDataURL and decoding uses atob and Blob, all in your browser. No network requests are made.

Should I include the data URL prefix?

It depends. For embedding directly into `background-image: url(...)` in CSS or an ` ` in HTML, keep it on (with `data:image/png;base64,`). For putting just the Base64 into an API body or JSON, turn it off to get the raw Base64.

Which image formats are supported?

Encoding works for any image file regardless of format (PNG / JPEG / WebP / GIF / SVG / AVIF / HEIC / BMP / TIFF, etc.) — it simply stringifies the raw bytes, so animated GIFs keep all their frames. Some formats like HEIC can't be previewed by the browser, and the generated data URL may not render directly in an img or CSS (the Base64 itself is still correct). For display use, convert to PNG / JPEG first with the HEIC → JPEG / AVIF convert tools, then run it through this tool.

Can I decode raw Base64 without a data URL prefix?

Yes. Without a prefix, the format is auto-detected from the leading magic-number bytes (PNG / JPEG / GIF / WebP / BMP / AVIF / SVG). If it can't be determined you'll get an error, so paste with the `data:image/ ;base64,` prefix when possible.

How does Base64 affect the size?

Base64 encodes 3 bytes as 4 characters, so the result is about 33% larger than the original image (plus a few dozen characters for the data URL prefix). It saves HTTP requests but is harder to cache, so it suits small icons and inline embedding.

Can it read URL-safe Base64 (- _)?

Yes. On decode, `-` and `_` are converted back to standard `+` and `/` and padding is restored, so URL-safe Base64 can be pasted as-is.

Back to Image

Image ⇄ Base64 — encode to data URL or decode back

Encode an image file into a Base64 string (data URL) or decode a Base64 / data URL back into an image. Handy for embedding in CSS / HTML, stringifying for API payloads, or inspecting a Base64 you received. Toggle the data URL prefix, and decoding auto-detects the image format for preview and download. Your image never leaves the browser — everything runs locally.

imageencodedecodeconversion

How to use

Pick 'Image → Base64' or 'Base64 → Image' at the top. In 'Image → Base64', drop or pick an image and the Base64 string is generated automatically. Turn on 'Include data URL prefix' to get the `data:image/png;base64,...` form (ready to paste into a CSS background or HTML img src), or turn it off for the raw Base64. Use 'Copy' or 'Download' (.txt) to take it. In 'Base64 → Image', paste a Base64 string or data URL and the image is restored with auto-detected format and previewed; 'Download' saves it as an image file in its original format. Images and text never leave the browser — everything runs locally with FileReader / atob / Blob.

FAQ

Is my image uploaded to a server?: No. Encoding uses FileReader.readAsDataURL and decoding uses atob and Blob, all in your browser. No network requests are made.
Should I include the data URL prefix?: It depends. For embedding directly into `background-image: url(...)` in CSS or an `<img src=...>` in HTML, keep it on (with `data:image/png;base64,`). For putting just the Base64 into an API body or JSON, turn it off to get the raw Base64.
Which image formats are supported?: Encoding works for any image file regardless of format (PNG / JPEG / WebP / GIF / SVG / AVIF / HEIC / BMP / TIFF, etc.) — it simply stringifies the raw bytes, so animated GIFs keep all their frames. Some formats like HEIC can't be previewed by the browser, and the generated data URL may not render directly in an img or CSS (the Base64 itself is still correct). For display use, convert to PNG / JPEG first with the HEIC → JPEG / AVIF convert tools, then run it through this tool.
Can I decode raw Base64 without a data URL prefix?: Yes. Without a prefix, the format is auto-detected from the leading magic-number bytes (PNG / JPEG / GIF / WebP / BMP / AVIF / SVG). If it can't be determined you'll get an error, so paste with the `data:image/<type>;base64,` prefix when possible.
How does Base64 affect the size?: Base64 encodes 3 bytes as 4 characters, so the result is about 33% larger than the original image (plus a few dozen characters for the data URL prefix). It saves HTTP requests but is harder to cache, so it suits small icons and inline embedding.
Can it read URL-safe Base64 (- _)?: Yes. On decode, `-` and `_` are converted back to standard `+` and `/` and padding is restored, so URL-safe Base64 can be pasted as-is.

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