Reverse Hex String — Endianness Swap, Byte Order, Free
Reverse hex strings: byte order, nibble order, or full string. Endianness conversion. Browser-only.
About Reverse Hex Digits
Reversing hex can mean three different things: reverse the entire string ("ABCD" → "DCBA"), swap byte order ("12 34 56 78" → "78 56 34 12" — endianness conversion), or swap nibbles within each byte ("AB" → "BA"). Each has different uses. The ZTools Reverse Hex tool offers all three modes. Most common use: byte-order swap, when converting between little-endian (Intel) and big-endian (network protocols) representations.
Use cases
- Convert between little-endian and big-endian. Network protocols use big-endian; x86/ARM use little-endian. A 32-bit value 0x12345678 is stored as 78 56 34 12 in memory but transmitted as 12 34 56 78. Tool swaps in either direction.
- Match a checksum / hash. Some tools display CRC / hash bytes in reverse order. Reverse to match the canonical representation.
- Debug endian-confusion bugs. A C struct serialised differently than expected — reverse the bytes to confirm endianness mismatch.
- Generate test vectors with reversed input. Test that your code handles both endiannesses correctly by feeding it both forms.
How it works
- Paste hex. With or without spaces / 0x prefixes. Whitespace stripped.
- Pick mode. Reverse string (full reversal char-by-char), swap bytes (reverse byte order), or swap nibbles (within each byte).
- Compute. String reversal is straight; byte swap chunks 2 chars at a time; nibble swap flips within each pair.
- Output. Result hex string in the same format (spaces preserved or removed per input).
Examples
Input: "12 34 56 78", swap bytes
Output: "78 56 34 12" — little-endian → big-endian (or vice versa).
Input: Same input, reverse string
Output: "87 65 43 21" — full string reversal, also swaps nibbles within each byte.
Input: "AB CD", swap nibbles
Output: "BA DC" — within each byte the high and low nibbles flip.
Frequently asked questions
Which mode for endianness?
Swap bytes. The byte order changes; the bits within each byte stay the same. This is the typical little-endian ↔ big-endian conversion.
When would I want full string reversal?
Rarely — full reversal is mathematically a different operation. Mostly useful for puzzle / curiosity work.
How big a hex string?
Megabytes work fine. The reversal is O(n).
Privacy?
All in browser.
Pro tips
- For endianness, almost always pick "swap bytes" — preserves byte values, changes order.
- For network-order (big-endian) data on x86 (little-endian), htonl / ntohl in C does this; tool does it in browser.
- Don't confuse with reversing bit order — that's a separate operation (use Invert Binary Bits with caution).
Reviewed by Ahsan Mahmood · Last updated 2026-05-06 · Part of ZTools.
For the full,
formatted version of this page, please enable JavaScript and reload
https://ztools.zaions.com/reverse-hex.