Scrawlspace › Developer Utilities

Base64 Encode & Decode

Encode text as Base64, Base64URL, percent-encoded URL, HTML entities, Unicode escapes or hex, or paste encoded text to decode it. Text is encoded as UTF-8 first, so emoji and non-English text work. Everything runs in your browser, with no size limits or sign-up. Base64 is an encoding, not encryption: anyone can decode it.

How to use Encode / Decode

1. Pick the Encoding: Base64, URL, HTML entities, Unicode escape or Hex.
2. Choose Encode or Decode as the Direction, and tick any options, such as URL-safe (no padding) for Base64URL.
3. Type or paste your text, or click Sample. The output updates as you type, with the character and byte count of each side.
4. Click Use as input to move the output to the input and flip the direction, or Copy it.

Frequently asked questions

How do I decode a Base64 string?

Choose Base64, set the direction to Decode and paste the string. The decoded text appears immediately, including non-English characters and emoji. If the bytes aren't UTF-8 text, they're shown as hex instead.

Is Base64 encryption?

No. Base64 is an encoding: anyone can turn it back into the original without a key. Never use it to hide passwords or secrets. To check that data hasn't changed, use a hash; to keep it private, use real encryption.

What is the difference between Base64 and Base64URL?

Base64URL (RFC 4648 section 5) replaces + and / with - and _ and usually drops the = padding, so the result is safe in URLs and file names. Tick URL-safe (no padding) to encode with it. The decoder accepts both forms, with or without padding. JWTs use Base64URL; to read one, use the JWT decoder.

Why is my Base64 longer than the original?

Every 3 bytes become 4 characters, so Base64 output is about 33% larger than the input, plus up to two = signs of padding to make the length a multiple of 4.

Why does my Base64 fail to decode?

Usually one of these: it has a data:image/png;base64, prefix (remove it, or decode the image with Base64 to Image); it was cut short, so the length is wrong; or it contains characters outside A–Z, a–z, 0–9, +, /, - and _. Whitespace, line breaks and missing padding are ignored.

How do I URL encode a string?

Choose URL and Encode. Spaces and special characters become percent codes such as %20. Tick Whole URL to keep :/?&= so a full address stays usable, or Spaces as + for form-style query strings.

How do I convert an image to Base64?

This page encodes text. For images, use Image to Base64, which gives a data URI you can paste into HTML or CSS.

Is my text sent to a server?

No. Encoding and decoding run in your browser.

How Base64 works

Base64 (RFC 4648) writes binary data using 64 safe characters: A–Z, a–z, 0–9, + and /. Each group of 3 bytes (24 bits) is split into four 6-bit values, and each value becomes one character. That is why the output is about 4/3 the size of the input, roughly 33% bigger. When the input isn't a multiple of 3 bytes, = signs pad the end.

For example, "Hello, Scrawlspace! 👋" encodes to SGVsbG8sIFNjcmF3bHNwYWNlISDwn5GL. The browser's own btoa() throws an error on emoji because it only takes Latin-1; this tool encodes the text as UTF-8 first, so it doesn't.

What each encoding is for

Encode a value vs a whole URL

By default URL mode works like JavaScript's encodeURIComponent: it escapes every reserved character, including / ? & =, which is right for a single query value. Whole URL works like encodeURI and keeps those characters, which is right for a complete address that only needs its spaces and non-ASCII characters escaped.