What is Base64 encoding?

Base64 converts binary data into an ASCII string format using 64 characters (A-Z, a-z, 0-9, +, /). It's commonly used to embed images in CSS/HTML or send data via APIs.

Does this tool upload my files?

No. All encoding and decoding happens in your browser. Your data never leaves your device.

Why is the Base64 string larger than the original?

Base64 encoding increases data size by roughly 33% because it represents 3 bytes as 4 ASCII characters.

Can I encode large files?

Yes, but very large files (50MB+) may be slow since processing is local. For images, most use cases are small icons or thumbnails.

What image formats are supported?

Any format your browser can read, PNG, JPG, GIF, WebP, SVG, and more.

How do I convert an image to Base64 in HTML?

Upload your image in our Image tab, then copy the generated data URI. Paste it directly into an img tag's src attribute, no server needed.

Can I use Base64 in CSS backgrounds?

Yes, use the CSS url(data:...) format. Encode your image here and wrap the output in url() for use as a background-image value.

A data URI embeds file data directly in a URL string using the format data:[mime];base64,[data]. It lets you include images and files inline without separate HTTP requests.

Base64 Encoder / Decoder

Encode text to Base64, decode Base64 to text, or convert images to data URIs. All processing runs in your browser.

EncodeDecode

Input

Output

What Is Base64?

Base64 is a binary-to-text encoding scheme that converts data into an ASCII string using 64 printable characters. It's widely used for embedding images in HTML/CSS, transmitting data in APIs, and encoding email attachments.

How to Use

Choose Text mode to encode/decode strings, or Image mode for files.
In Text mode, paste your input and click Encode or Decode. Use Auto-Detect to let the tool guess the direction.
In Image mode, drop or upload a file to generate a Base64 string, data URI, and img tag.
Copy any output with one click.

Last updated: March 2026

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Base64 Encoder / Decoder

What Is Base64?

How to Use

Frequently Asked Questions

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Base64 Encoder / Decoder

What Is Base64?

How to Use

Frequently Asked Questions

What is Base64 encoding?

Does this tool upload my files?

Why is the Base64 string larger than the original?

Can I encode large files?

What image formats are supported?

How do I convert an image to Base64 in HTML?

Can I use Base64 in CSS backgrounds?

What is a data URI?

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HTML CSS JS Minifier

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Need Something Custom?

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