Base64 Encoder & Decoder
Paste text or Base64 and get both forms at once. Runs entirely in your browser — nothing is uploaded.
Type or paste anything below. You get the Base64 encoding and the decoding of the same input side by side, so you don't have to know which direction you needed.
Paste either. Both directions are shown below.
Encoded to Base64
Whatever is in the box, written in Base64. The sample IS Base64, so this encodes it a second time.
U0dWc2JHOHNJSGR2Y214a0lRPT0=
Decoded from Base64
Empty if what you pasted isn't valid Base64 — that is how you can tell.
Hello, world!
URL-safe Base64
The base64url variant used in JWTs and query strings: + becomes -, / becomes _, and padding is dropped.
U0dWc2JHOHNJSGR2Y214a0lRPT0
About this tool
What Base64 Actually Is (And What It Isn't)Base64 turns any data into 64 safe characters so it survives text-only channels. Here's how it works, why it's 33% bigger, and why it is not encryption.
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Base64 & Encoding Cheat SheetThe rules worth remembering, and the ones people get wrong most often. Same figures this tool uses.
Free, no email required — print it or save it as a PDF.
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Base64 Encoder & Decoder infographicThe key numbers as one image — free to save, share, or embed on your own site with credit.
How this works
Base64 rewrites data using only 64 safe characters — A-Z, a-z, 0-9, + and / — so it survives places that would mangle raw bytes, like email headers, JSON strings and data URLs. Every 3 bytes of input become 4 Base64 characters, which is why encoded text is about 33% longer than what you started with. When the input doesn't divide evenly into 3, the result is padded with = signs. Text is treated as UTF-8, so accented characters and emoji encode and decode correctly. If the decoded box is empty, the input wasn't valid Base64. Everything runs in your browser. Nothing you paste is sent anywhere.
Common questions
- Is Base64 encryption?
- No. Anyone can decode it — this page does it in one step. Base64 makes data safe to transport, it does not make it secret. Never use it to hide a password.
- Why is my encoded text longer than the original?
- Base64 turns every 3 bytes into 4 characters, so the result is roughly 33% bigger. That is the cost of using only characters that survive text-only channels.
- What are the = signs at the end?
- Padding. Base64 works in blocks of 3 bytes, so when the input doesn't divide evenly, one or two = are added to fill the last block.
- Is anything I paste sent to your server?
- No. The encoding and decoding happen in your browser. Nothing leaves your machine.
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Part of a bigger job
Encoding Tools Every Developer NeedsBase64, URL encoding, JSON and slugs — four everyday conversions, why each shows both directions at once, and the encoding choice that actually matters.
Walks through all 4 encoding & developer tools in order.