ASCII to Hexadecimal Converter Free Online Tool
Convert ASCII to hexadecimal - code points or UTF-8 bytes, uppercase, 0x-prefix, JSON-array output. Free, client-side, instant, offline.
Convert text to hexadecimal base-16 numbers β pick code points (one token per visible character, emoji-safe) or UTF-8 bytes, plus separator, case, padding, and prefix controls.
How to Use ASCII to Hexadecimal Converter Free Online Tool
- Paste your text into the input - ASCII, Latin characters, CJK, and emoji are all accepted. The output recomputes within 150 ms of every keystroke.
- Pick an encoding mode. Code points (default) gives one token per visible character (π β
1F600). UTF-8 bytes emits the actual on-the-wire sequence (π βF0 9F 98 80, δΈ βE4 B8 AD) - this is what you want for hex dumps, wire-format debugging, or constructinguint8_t[]. - Pick a separator: space (default, readable), comma (CSV-style), newline (one token per line), "None" for a continuous hex dump, or JSON array for a copy-paste-ready literal.
- Toggle UPPERCASE - on by default for this variant because hexadecimal literals are traditionally written uppercase in programming contexts (
0xFF). Disable forxxd-style lowercase dumps. - Toggle zero-pad to force fixed-width tokens (
01 08 0Finstead of1 8 F). On by default so every output has consistent alignment. - Add a per-token prefix like
0xto produce C/JS/Go/Rust-ready integer literals directly from the output. - Check the stats line for mode, character count, token count, min/max value (in
0xFFform), and any skipped-count. Copy, Download, orCtrl+Enter(β+Enteron Mac) to run and copy in one shortcut.
Frequently asked questions
What is hexadecimal?
A base-16 number system using the digits 0-9 plus the letters A-F (or a-f in lowercase). Each hex digit represents 4 bits, so one byte (8 bits) fits cleanly in exactly two hex digits – which is why hex is the standard way to write raw bytes.
Why convert text to hex?
For debugging (protocol dumps, serial output, binary diffs), building firmware literals, memory inspection, defining CSS/HTML color codes, or generating test fixtures. It is the clearest way to see exactly which bytes a string produces.
What is the output format?
Depends on your picks. The default is space-separated 2-character uppercase pairs (48 65 6C 6C 6F), but you can also get comma/newline-separated, a continuous dump, or a JSON array literal – each token optionally prefixed with 0x.
Is my text secure?
Yes. Conversion runs entirely in your browser – nothing is uploaded, cached, or tracked. After the page loads you can disconnect the network and keep encoding indefinitely.
Uppercase or lowercase hex?
Convention varies. Programming literals (C, Go, JSON, JavaScript) usually put letters uppercase after 0x; xxd-style hex dumps and Unix tools tend toward lowercase. Flip the UPPERCASE toggle to match whatever consumer expects.
Does it work offline?
Yes. HTML, CSS, and JavaScript are self-contained. Once the page has loaded, you can turn off Wi-Fi and keep encoding – useful on air-gapped machines.
Is it free?
Yes, 100% free with no cap on input length or number of conversions. No sign-up, no premium tier, no watermark.
Does it handle Unicode properly?
Yes. The default Code points mode uses codePointAt so emoji like π render as a single token (1F600), not two surrogate halves. Switch to UTF-8 bytes when you need the actual byte sequence – π then becomes four bytes F0 9F 98 80, and δΈ becomes E4 B8 AD.
What is the difference from a plain “ASCII to Hex” tool?
Just the name – “hexadecimal” is the full form of “hex”, and some contexts prefer one over the other. The output is identical to the sibling tool, and both round-trip cleanly with the corresponding decoder.
How do I convert hex back to text?
Use the sibling Hexadecimal to ASCII converter. Both tools share the same mode selector so any output here pastes back cleanly there, emoji and all.