Base32 Decoder

Base32 decoder reads the RFC alphabet and returns UTF-8 text. JBSWY3DP becomes Hello. The same code in lowercase also becomes Hello.

JBSWY3DP is Hello

The alphabet is A through Z and the digits 2 through 7. Padding equals signs are stripped before the bits are read. JBSWY3DP and the same text with trailing equals both return Hello. Lowercase is uppercased first, so jbsy returns He, which is the text those bits can fill. Characters outside the alphabet are deleted rather than rejected. A string of only exclamation marks therefore returns an empty result, with no error. A box of only spaces throws Base32 is required. The label is Process. There is no checksum. There is no download. The result is text you copy. A second press on Hello the code reprints Hello.

What the bits do not check

There is no Crockford alphabet and no check symbol. A character that is not in A to Z or 2 to 7 is dropped, including 0, 1, 8, and 9. Leftover bits that do not fill a byte are discarded, which is why a short group can return a shorter string instead of an error. The decoder does not verify padding length. It only removes equals from the end. This page does not encode. The encoder is a separate control. An empty result after stripping is not the same as the required-text error. The required-text error appears only when the box is empty or spaces. Digits 8 and 9 leave with 0 and 1.

How to check Hello

Paste JBSWY3DP and press Process. The result should be Hello. Paste the same code in lowercase and expect Hello. Add equals at the end and expect Hello again. Paste jbsy and expect He. Paste only exclamation marks and expect an empty result, not an error. Clear the box and expect Base32 is required. If the result is still the code you pasted, Process did not run. Digits 0 and 1 are not in the alphabet, so they are removed before the bits are grouped. The page will not tell you that a checksum matched, because it does not compute one. Padding equals are removed before the alphabet is read, so they do not change Hello.

The code stays in this tab

The decode runs in this browser. The code is not uploaded. Paste a string, press Process, and copy the text. Closing the tab drops both boxes. There is no saved copy. JBSWY3DP is Hello. Lowercase is accepted. Equals padding is ignored. Exclamation marks alone return an empty result. A blank box throws Base32 is required. Process is the label. There is no file name. No checksum is checked. The encoder is not this page. JBSWY3DP with trailing equals is still Hello. The short group jbsy is He, because leftover bits that do not fill a byte are dropped. Digits 0 and 1 are deleted before the bits are grouped. A string of only exclamation marks returns an empty result rather than an error. The required-text error appears only when the box is empty or spaces.