How do I read the three columns of a hex dump?

Read it left to right. The first column is the offset, an 8 digit hex address telling you how many bytes precede this row, so the first row starts at 00000000 and a 16 byte row puts the next at 00000010. The middle column is the raw bytes, two hex digits each, grouped so you can count them. The right column is the ASCII preview. So the line 00000000 48 65 6c 6c 6f |Hello| reads as offset 0, the bytes 48 65 6c 6c 6f, spelling Hello.

What does the offset column mean and why is it hex?

The offset is the byte position where each row begins, counted from the start of the data. It is shown in hexadecimal because byte addresses are naturally base 16: 00000010 is decimal 16, 00000020 is decimal 32. With 16 bytes per row each new row adds 0x10 to the offset, so 00000000, 00000010, 00000020 and so on. This matches how xxd, hexdump and every hex editor number their rows, which makes it easy to jump to a known position.

What is the dot in the ASCII column?

Each dot stands for one byte that is not a printable ASCII character. Bytes 0x20 through 0x7e (space through tilde) print as themselves, everything else, control characters like 0x00 or a newline 0x0a, and every byte of a multibyte UTF-8 sequence, shows as a dot so the column stays one character wide per byte. So a tab and a null byte both look like a dot here even though their hex values differ, which is exactly what xxd does.

How many bytes does a Chinese character take in the dump?

Three bytes in UTF-8. This viewer runs your text through TextEncoder, so 中 becomes e4 b8 ad, three separate bytes that each get their own hex pair and their own dot in the ASCII column. A two character word like 你好 is six bytes, e4 bd a0 e5 a5 bd. An emoji is usually four bytes. That is the real on disk size, the same count a server or a file would report, not the single character you typed.

Is this the same output as the xxd command?

The layout matches xxd and hexdump -C closely: 8 digit offset, space grouped hex, and a piped ASCII column |like this|. The main difference is the source, this tool dumps the UTF-8 bytes of the text you paste, while xxd dumps a file, so byte for byte the bytes are identical for the same content. Set 16 bytes per row to mirror the classic default. Use it to preview what xxd would show before you reach a terminal, or to share a dump as a link.

Inspect exactly what bytes a string contains

You suspect a config value has a stray byte, maybe a non breaking space or a hidden BOM. Paste the string and the dump shows every byte by offset. A normal space is 20, a non breaking space is c2 a0, and a BOM is ef bb bf, all of which jump out in the hex column the moment you look, where the rendered text hid them.

Teach or learn how UTF-8 encoding works

Type one ASCII letter, one accented letter, one CJK character and one emoji on the same line and watch the byte counts: 1, 2, 3 and 4 bytes. The offset column makes the growth concrete and the ASCII column shows dots for every continuation byte, which is the clearest way to see why string length and byte length differ.

Preview an xxd dump before opening a terminal

You want to know what xxd would print for a short snippet but you are in a browser, not a shell. Paste the text, set 16 bytes per row, and you get the same offset, hex and ASCII layout you would see from xxd, ready to copy into a bug report or a chat message.

Share a byte level view as a link

Debugging an encoding issue with a teammate over chat? Build the dump here, the input and your row width and case live in the URL, and send the link. They open it and see the identical three column dump without you having to paste a wall of pre formatted text.

Hex Dump Viewer, Offset + Hex + ASCII

Offset, hex bytes and ASCII side by side, the classic xxd / hexdump -C layout, fully in your browser

Runs locally
Category Developer & DevOps
Best for Formatting, validating, shrinking, or inspecting code-adjacent text.

Bytes / row

Case

Input text

Hex dump

The hex dump appears here.

What this tool does

Free online hex dump viewer that turns any text into the classic three column layout you know from xxd and hexdump -C: an 8 digit offset on the left, the raw bytes in the middle grouped two digits at a time, and an ASCII preview on the right. It encodes your input as UTF-8 first, so a Chinese character such as 中 shows up as its real three bytes e4 b8 ad and an emoji shows as four bytes, exactly the way a file, a socket or a hex editor would store them. Printable characters appear in the ASCII column unchanged; control bytes and anything non printable collapse to a single dot so the column stays aligned. Pick 8, 16 or 32 bytes per row, flip the digits between lower and upper case, and copy the whole dump with one click. Everything runs locally in the page, nothing is uploaded, and the input plus your options round trip through the URL so a shared link reopens the exact same dump.

Tool details

Input: Text + Numbers; The page exposes text boxes, numeric controls, file pickers, or structured inputs depending on the tool.
Output: Live result + Copy + Preview; The result area focuses on usable output, with copy, download, or preview actions when supported.
Privacy: Browser-side processing; The main tool logic does not call an external API, so inputs normally stay in the current tab.
Save / share: Shareable URL state; Key settings are encoded in the URL so another person can reopen the same setup.
Performance budget: Initial JS <= 9 KB; No WASM budget is declared, keeping the tool quick to open on mobile.
Best fit: Developer & DevOps · Developer; Category and role tags drive related tools, internal links, and quick fit checks.

How to use

1. Input

Paste or drop your content into the tool panel.
2. Process

Click the button. All processing is local in your browser.
3. Copy / Download

Copy the result or download to disk in one click.

How Hex Dump Viewer fits into your work

Use it in the small gaps between coding, reviewing, debugging, and shipping.

Developer jobs

Formatting, validating, shrinking, or inspecting code-adjacent text.
Preparing snippets for documentation, tickets, commits, or handoff.
Checking a small payload quickly without switching tools.

Developer checks

Run irreversible transforms like minify or obfuscate on a copy.
Keep secrets out of pasted snippets unless the tool explicitly stays local.
Use your normal tests or linter before shipping transformed code.

Good next steps

These links move the current task into a more complete workflow.

Real-world use cases

Inspect exactly what bytes a string contains
You suspect a config value has a stray byte, maybe a non breaking space or a hidden BOM. Paste the string and the dump shows every byte by offset. A normal space is 20, a non breaking space is c2 a0, and a BOM is ef bb bf, all of which jump out in the hex column the moment you look, where the rendered text hid them.
Teach or learn how UTF-8 encoding works
Type one ASCII letter, one accented letter, one CJK character and one emoji on the same line and watch the byte counts: 1, 2, 3 and 4 bytes. The offset column makes the growth concrete and the ASCII column shows dots for every continuation byte, which is the clearest way to see why string length and byte length differ.
Preview an xxd dump before opening a terminal
You want to know what xxd would print for a short snippet but you are in a browser, not a shell. Paste the text, set 16 bytes per row, and you get the same offset, hex and ASCII layout you would see from xxd, ready to copy into a bug report or a chat message.
Share a byte level view as a link
Debugging an encoding issue with a teammate over chat? Build the dump here, the input and your row width and case live in the URL, and send the link. They open it and see the identical three column dump without you having to paste a wall of pre formatted text.

Common pitfalls

Counting a Chinese character or emoji as one byte. In UTF-8 a CJK character is three bytes and most emoji are four, so the byte length is larger than the visible character count. The dump shows the true byte count per row, which is what matters for buffer sizes and file lengths.
Reading the offset as decimal. The offset column is hexadecimal, so 00000010 is byte 16, not byte 10. If you need a decimal position, convert the hex offset first, or the row math will be off by the base.
Expecting the ASCII dots to be meaningful characters. A dot is just a placeholder for any non printable byte, it does not mean the byte is a period (which would be 2e). Two different control bytes both show as a dot, so always read the value from the hex column, not the ASCII preview.

Privacy

The whole dump, the UTF-8 encoding, the offset math and the ASCII preview, is plain JavaScript that runs inside your browser tab. The text you paste never leaves the page and nothing is logged. The one thing to know: the input and your options are stored in the page URL so a shared link can reopen the same dump, which means a link pasted into chat will record your text in the recipient server access log. For anything sensitive, use the copy button and paste the dump text rather than sharing the URL.

FAQ

Tool combos

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Developer

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Hex Dump Viewer, Offset + Hex + ASCII

What this tool does

Tool details

How to use

1. Input

2. Process

3. Copy / Download

How Hex Dump Viewer fits into your work

Developer jobs

Developer checks

Good next steps

Real-world use cases

Inspect exactly what bytes a string contains

Teach or learn how UTF-8 encoding works

Preview an xxd dump before opening a terminal

Share a byte level view as a link

Common pitfalls

Privacy

FAQ

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