Base64 is an encoding scheme that converts binary data into ASCII text using 64 printable characters. It is widely used in email (MIME), data URIs, JWTs, and API authentication. One Base64 character represents 6 bits, so the output is approximately 33% larger than the input. Runs entirely in your browser.
Base64 encodes binary data as 64 printable ASCII characters (A–Z, a–z, 0–9, +, /) so it can be safely embedded in contexts that only support text — email bodies, JSON fields, XML attributes, and HTTP headers. This encoder works entirely client-side: no data is sent to any server.
Email clients use Base64 (via MIME) to attach binary files. JWTs (JSON Web Tokens) encode their header and payload in URL-safe Base64. Basic Auth headers send credentials as Base64(username:password). Data URIs (data:image/png;base64,...) embed binary images directly in HTML or CSS. Understanding when Base64 is appropriate — and when it isn't — helps you avoid bloating payloads unnecessarily.
+// with -/_)= padding on all outputStandard Base64 uses + and /, which have special meaning in URLs. URL-safe Base64 replaces them with - and _, making the string safe in query parameters and path segments without percent-encoding.
No — it expands it. Every 3 bytes become 4 characters (a 33% increase). Base64 is a text representation, not a compression format. Compress first if needed, then encode.
No. Base64 is trivially reversible — anyone can decode it. It is encoding, not encryption. If you need to protect content, use AES encryption, not Base64.
= or ==?Base64 works in 3-byte groups. When the input length is not a multiple of 3, padding equals signs are added to complete the last group: one = for 2 remaining bytes, == for 1 remaining byte.
See also the File to Base64 converter for encoding binary files, and the Base32 / Base58 tools for other formats.