Online Base64 Encoder & Decoder
Online Base64 encoder/decoder supporting any Unicode text and a URL-safe variant. Runs entirely in the browser — input is never uploaded.
Usage
Base64 encodes binary data as printable ASCII — commonly used in URLs, email attachments, Data URLs and cookies.
Uses the browser's btoa / atob with extra UTF-8 handling so non-ASCII text (CJK, emoji) round-trips correctly. The "URL safe" option replaces +// with -/_ and strips trailing =.
Use cases
FAQ
Why does Base64 make the data larger?
Base64 expands every 3 bytes to 4 characters — about 33% overhead.
What is URL-safe mode?
Replaces + with -, / with _ and strips trailing =. The result can be embedded in URLs without further percent-encoding.
Does it handle CJK and emoji?
Yes. The tool first encodes the string as UTF-8, then Base64s the bytes — any Unicode round-trips correctly.
Is Base64 encryption?
No. It's encoding, not encryption — anyone can decode it. Never use it to protect sensitive data.