Base64 Encode

What this tool does

Base64 encoding turns arbitrary text (or binary data) into a string made up only of letters, digits, and a few symbols — an alphabet safe to put inside places that only reliably handle plain ASCII text, like email bodies, URLs, JSON strings, and HTTP headers. This tool encodes UTF-8 text to Base64 entirely in your browser, with an option for the URL-safe variant.

When you need it

• Embedding binary-ish or special-character data inside a JSON field, a URL, or a config file without worrying about escaping.
• Building the Authorization: Basic header for HTTP Basic Auth, which requires username:password to be Base64-encoded.
• Preparing a value to paste into a system (some webhook payloads, some legacy APIs) that expects Base64 rather than raw text.
• Understanding what a Base64 string you're about to send actually contains, by encoding a known value and comparing.

Rules the encoder applies

1. Text is encoded as UTF-8 bytes first, then those bytes are mapped to Base64 characters three bytes at a time. This matters because a character count and a byte count aren't the same thing once accented letters, emoji or other non-ASCII characters are involved — those take two to four bytes each in UTF-8.
2. Standard Base64 uses +, / and = padding. This is the default and the form most systems (email, most APIs) expect.
3. URL-safe Base64 replaces + with - and / with _, and omits the = padding. This is the form used inside JWTs and in URL query parameters, where +, / and = would otherwise need percent-encoding to be safe.
4. The output length is always a multiple of 4 characters in standard mode (using padding to reach that), and 0–2 characters shorter in URL-safe mode, where the padding is dropped.

Why the output is longer than the input

Base64 represents every 3 bytes of input as 4 characters of output, so encoded text is roughly 33% larger than the original. This is an expected, unavoidable property of the encoding — it's not evidence of anything going wrong, and it's the trade-off for making binary-safe data usable as plain ASCII text.

Things to check after encoding

• If you need the result inside a URL, use the URL-safe option rather than percent-encoding a standard Base64 string afterward — it produces a cleaner, shorter result.
• Base64 is not encryption or compression. Anyone who sees the encoded string can decode it back to the original text in one step; never use Base64 alone to protect a secret or password.
• If you're building an HTTP Basic Auth header, remember the input format is username:password (with a literal colon) before encoding, not just the password.

Limits

Input is capped at 2 MB of text. This tool encodes text input, not raw binary files — for encoding an image or other binary file to Base64, you need a file-reading tool rather than a text box.