Base64 Encoder and Decoder

Base64 represents bytes using letters, digits, +, / and padding with =. This tool uses the standard Base64 alphabet defined in RFC 4648.

Base64 is an encoding, not encryption. Anyone can decode it; it does not protect passwords or other secrets.

Every three bytes become four characters. The exact output length is 4 × ceil(byte count ÷ 3), so large inputs grow by about 33%. Short inputs can grow by much more because of padding.

Choose Encode and enter UTF-8 text. For example, Hello, world! becomes SGVsbG8sIHdvcmxkIQ==. Choose Decode to reverse the conversion, or use the result-transfer button to switch with your result already filled in.

Accented letters and emoji are supported. A leading BOM (U+FEFF) is preserved. Invalid UTF-8 is reported as an error instead of being replaced with garbled text.

The decoder accepts omitted trailing padding and ASCII wrapping whitespace: spaces, tabs, line feeds, carriage returns and form feeds. It rejects invalid padding and non-zero unused trailing bits. Base64URL uses a different alphabet; - and _ are not accepted here.

In Decode mode, choose Load an image file to create a Base64 data URL from a PNG, JPEG, GIF, WebP or static SVG. You can also paste a supported image data URL or raw Base64 image data to preview it.

The tool detects the format from the actual bytes and checks any declared MIME type against them. Copying an image data URL becomes available only after the browser can display the image. A failed file replacement keeps your previous valid result.

SVGs are limited to 20,000 markup fragments, 64 KiB of CSS and 256 nesting levels. Scripts, event handlers, animation, external references and embedded resources are rejected. This is a restricted static SVG workflow, not a general-purpose SVG sanitizer.

UTF-8 input, image files and decoded data are limited to 2 MiB (2,097,152 bytes, shown as 2.0 MB in the tool). Base64 data can contain at most 2,796,204 non-whitespace characters plus 131,072 ASCII whitespace characters. Input and output sizes use binary units.

Conversion and image validation run locally in your browser; the tool does not upload your text or images. Site analytics and advertising may make separate network requests. Avoid entering sensitive information on a shared device.

Typical uses include small images in HTML or CSS data URLs, API fields, MIME attachments and PEM files. Check the receiving application's format and size limits. HTTP Basic authentication also uses Base64, but transport security depends on HTTPS. Standard Base64 is not automatically safe to insert into a URL; check whether the destination requires percent encoding or Base64URL.

If a clipboard write remains pending, the tool prevents a second write from starting even after you leave and return to this page. Select the output to copy manually, or retry after the pending write finishes.