How to use the Base64 encoder
Pick a direction with the tabs. Encoding converts text — or a dropped file — into Base64 as you type; decoding turns Base64 back into text, accepting both the standard and URL-safe alphabets, with or without padding. If a decoded payload turns out to be binary rather than text, you can download the raw bytes as a file instead.
What Base64 actually is
Base64 represents arbitrary bytes using 64 printable characters, so binary data can travel through channels that only speak text — JSON payloads, data URIs, email attachments, JWT segments. Two things worth knowing: it grows data by about 33% (every 3 bytes become 4 characters), and it is not encryption — anyone can decode it instantly. If you need secrecy, you need actual cryptography; Base64 only provides safe transport.
Standard vs URL-safe
Standard Base64 uses + and /, which collide with reserved characters in URLs and filenames. The URL-safe variant (RFC 4648 §5) swaps them for - and _ and usually drops the = padding. JWTs, web push keys and many APIs expect the URL-safe form — the checkbox switches the output, and the decoder accepts either automatically.
Frequently asked questions
Is my text or file uploaded anywhere?
No. Encoding and decoding run entirely in your browser — files are read locally and never leave your device. Safe for tokens, configs, and private documents.
Is Base64 a form of encryption?
No — it's an encoding, not encryption. It has no key and no secrecy; anyone can reverse it. Never rely on Base64 to protect sensitive data.
Why is the output bigger than my input?
Base64 spends 4 characters for every 3 bytes of input, so output is about a third larger — the size-change stat shows the exact overhead. That cost buys you data that survives any text-only channel.