Base64 Encode/Decode

Base64 turns arbitrary bytes into a string made only of A–Z, a–z, 0–9, +, /, and a trailing = for padding — a character set safe to drop into places that were only ever designed for plain text, like JSON fields, email bodies, URLs, or a Basic Auth header. It isn't encryption and isn't compression; encoded text is actually about 33% larger than the original, since every 3 bytes of input become 4 Base64 characters. Anyone can decode it instantly, so never use Base64 as a way to hide secrets — use it purely as a text-safe transport format.

The most common mistake is handling non-ASCII text with the browser's built-in btoa()/atob() directly — they operate on UTF-16 code units, not bytes, and throw or corrupt data on anything outside Latin1 (accented letters, CJK text, emoji). This tool encodes through TextEncoder first, so café, 日本語, and 🚀 all round-trip correctly, matching how Base64 is actually used in modern JSON APIs and JavaScript code.

• •Never treat Base64 as encryption — it's a reversible text encoding with no key, decodable by anyone in one line of code.
• •For binary files (images, PDFs), use a data URI (data:image/png;base64,...) rather than a bare Base64 string, so the receiving context knows how to interpret the bytes.
• •Base64url (using - and _ instead of + and /, and usually no = padding) is a different variant used in JWTs and URLs — a value copied from one context may need those characters swapped before it decodes elsewhere.
• •Whitespace and line breaks inside a Base64 string are usually safe to strip before decoding — this tool does that automatically — but don't assume every decoder is that forgiving.