What does the Base64 do?
Base64 represents binary data as ASCII. This tool encodes UTF-8 text to Base64 and decodes it back, which is useful for data URLs, HTTP basic auth blobs and inspecting encoded payloads.
Base64 Encode / Decode
Convert text to Base64 and back without uploading. Nothing is uploaded.
The Base64 tool encodes UTF-8 text per RFC 4648 at exactly 4 output characters per 3 input bytes — a +33.3% size overhead before padding — entirely in the browser.
How does the Base64 work?
Encoding uses TextEncoder then btoa. Decoding reverses that with atob and TextDecoder. Both steps run in JavaScript in this tab.
Does this upload my data?
No. This page never sends your input to a server — formatting, decoding and hashing all run in this tab, on this device.How that works.
Frequently asked questions
Does this handle UTF-8?
Yes. Plain btoa fails on emoji and non-Latin text; this tool encodes UTF-8 bytes first so those characters survive a round trip.
Can I decode JWT segments here?
You can, but JWT uses Base64URL (different alphabet, no padding). Use the JWT decoder for tokens.
Is whitespace allowed?
Decode strips whitespace before parsing, so wrapped Base64 from emails still works.
Is data uploaded?
No. Encoding never leaves the browser.
Do one job
Guides
Related tools
JWT DecoderInspect header and payload of a JSON Web Token locally.URL EncodePercent-encode query strings, paths and fragments.HTML EntitiesEscape text for HTML and decode entities back to text.Query ↔ JSONTurn URL query strings into JSON and back.
Browse allencoding toolsor thefull tool directory.