Input
Preparing your workspace…
How to use
- Paste hexadecimal data, with optional spaces and one leading 0x.
- Choose byte order or digit reversal; select a word size for byte order.
- Copy the result or use it as input to reverse again.
Byte order is different from digit order
A byte is written as two hexadecimal digits. Reversing 12 34 by bytes gives 34 12; reversing individual digits gives 43 21, which describes different bytes.
The default operation reverses byte order. A separate digit mode is available for string-manipulation tasks, so the two meanings of “reverse hex” remain explicit.
Representations and workflow
Whole input reverses every byte in the sequence. With 2-, 4- or 8-byte groups, each complete group is reversed independently while the group order remains unchanged.
12 34 56 7878 56 34 12Whole-input byte reversal preserves each two-digit byte. Digit reversal would give 87654321.
Precision and validation
Byte mode requires an even count of hex digits and a byte count divisible by the selected word size. Incomplete bytes are rejected; no zero padding is guessed.
Interpreting and reusing the result
The operation preserves all accepted byte values, including leading 00 bytes. It does not detect a source CPU, infer a target endianness or interpret a numeric sign.
Numbers: up to 500 lines / 1 MiB, at most 4,096 characters per numeral. Fraction output: 1–128 digits. Text and byte data: 64 KiB. Bitwise operations: 8–256 bits. Workers stop after 30 seconds; inputs are not uploaded.
Frequently asked questions
Does this convert big-endian to little-endian?
It reverses the byte order you choose. Whole-input reversal works for a single value; choose a word size when a buffer contains several independent values.
What happens to an odd number of hex digits?
Byte mode reports an incomplete-byte error. Digit mode can reverse an odd-length string because it is a different operation.
Are leading zero bytes preserved?
Yes. Each byte stays two hex digits, including 00. This is byte manipulation rather than a numeric conversion that removes leading zeros.
Is my input sent to a server?
No. Computation runs in a browser worker. DevToolsy does not upload or store your input.
What does Copy include?
Copy exports the selected displayed value. Download JSON preserves strings and diagnostic codes; it does not turn large numbers into floating-point values.