JavaScript to Base64 Converter
Encode plain text or Unicode strings to Base64 with UTF-8 handling, URL-safe option, and instant copy.
What is JavaScript to Base64 Converter?
The JavaScript to Base64 Converter encodes arbitrary Unicode text to Base64 using UTF-8 bytes first—so emoji and non-Latin scripts work—
with an optional URL-safe alphabet that replaces + and / and strips padding, matching RFC 4648 section 5.
Why not raw btoa?
Browser btoa is defined on single-byte Latin-1 style strings. Feeding it UTF-8 text throws on many characters. This tool uses
TextEncoder first, then btoa on the byte sequence, which matches what APIs expect for modern text.
How to use
- Paste or type text on the left.
- Toggle URL-safe Base64 if you need filenames, query strings, or JWT-like segments.
- Copy the Base64 string from the output panel.
Frequently Asked Questions
When should I use URL-safe Base64?
Use it when the result will be embedded in URLs or tokens where +, /, or = would need extra escaping.
Remember that consumers must decode with the matching alphabet and padding rules.
Is encoding lossy?
No. Base64 is a reversible representation of the same UTF-8 bytes; decoding with the correct settings returns identical text.
Can I encode huge documents?
Very large strings can slow the tab or hit memory limits. For big files, prefer streaming encoding in a backend or dedicated binary pipeline.
Does this sign or encrypt data?
No. Base64 is not encryption. Anyone can decode it. Do not use it as a security control—use proper encryption and signatures instead.
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