Binary Decoder

Formats the binary decoder reads

A binary decoder turns encoded bytes back into readable text. Bytes can be written in several number systems, and this decoder reads all the common ones. Here is the same text, “Hi!”, in each format:

Binary, octal, decimal and hex all write one number per byte; they only differ in the base. Hex is the most compact of the four, two digits per byte. Base64 works differently: it packs every three bytes into four characters, which makes it shorter still and safe to paste into email, URLs and JSON.

How auto-detect works

With Read as set to Auto-detect, the decoder looks at what you pasted and picks the first format that fits, in this order:

1. Binary if every group contains only 0s and 1s.
2. Hex if the groups use hex digits and also have a 0x prefix, a letter A–F, exactly two digits each, or form one long even-length run.
3. Decimal if every group is a number from 0 to 255.
4. Base64 if the input uses only Base64 characters and its length fits Base64, or it ends in =.

The line above the input tells you which format was chosen. Some inputs are genuinely ambiguous: 48 69 is valid hex and valid decimal. Auto-detect picks hex, because hex bytes are always two digits. If that’s wrong, pick the format yourself in Read as. Octal is never auto-detected, since octal bytes also look like decimal, so choose Octal manually.

Where you’ll find encoded text

• Puzzles and CTF challenges often layer encodings, for example Base64 that decodes to hex that decodes to text. Decode, swap, and decode again.
• Network and file dumps show bytes in hex. Paste a run of hex to see whether it contains readable text.
• Email, URLs and APIs carry text and attachments as Base64, including the URL-safe variant with - and _, which the decoder accepts.
• Source code writes bytes as 0x48 or 0b01001000. Both prefixes are understood.

Decoding tips

• If the result is unreadable or shows �, the bytes may not be text: they could be an image, compressed data or encrypted.
• Use the swap button to re-encode a result and compare it with your input. It keeps the same base; Base64 input is re-encoded as binary.
• Only have binary? The binary to text translator is tuned for that, including 7-bit groups.

Frequently asked questions