Hex Converter

Hexadecimal is the way software talks about bytes: base-16, where each pair of digits (00 to ff) represents exactly one byte. It appears everywhere in technical work — color codes, memory dumps, MAC addresses, binary file headers, hash outputs, escape sequences — and converting between hex and human-readable forms is a daily micro-task this tool makes instant.

Two modes cover the two different questions people mean by "hex conversion." Text mode converts a string to its UTF-8 bytes as hex pairs and back — paste "Hello", get 48 65 6c 6c 6f; paste a hex dump, recover the text. Decoding is deliberately tolerant: spaces, newlines and 0x prefixes are all ignored, so hex copied from any source just works. Number mode converts between decimal and hexadecimal in both directions, live, as you edit either field.

The number mode has one property worth calling out: it uses big-integer arithmetic, so conversion is exact at any size. Most online converters silently corrupt numbers above 9,007,199,254,740,991 (JavaScript's float precision limit) — a real problem when converting database IDs, timestamps in nanoseconds, or cryptographic values. Here, a 40-digit number converts as precisely as a 4-digit one. Entirely in your browser, both directions, no limits.