Web Serial Terminal

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hex serial terminal online

Hex serial terminal online

Switch the display to Hex and each line shows the raw bytes, terminator included, with the ASCII characters beside them. When sending, change the format to Hex and type the bytes. For data with no line breaks, use As it arrives in the port options.

Bytes, text and the three ways to send

In binary protocols, a byte such as 0x00 or 0xFF is not text. The Hex view shows each byte as two uppercase digits separated by a space, and the column beside it replaces anything not printable with a dot, the classic dump format. The line ends where the device sent LF, CRLF or CR, and the tool shows the terminator in the hex: 48 69 0D 0A is the word Hi followed by CRLF.
There are three ways to send. In Text mode, the input goes out as UTF-8, so ç sends C3 A7. With the escapes option on, \n, \r, \t and \0 become their bytes and \xNN sends an arbitrary byte: caf\xE9 sends 63 61 66 E9, with a byte that is not UTF-8. In Hex mode, the input accepts 48 65 6C, 0x48,0x65,0x6C, 48:65:6C or 48656C, and warns if a digit is missing or an invalid character appears.
The chosen line ending is added after the bytes in any mode: LF adds 0A, CR adds 0D, CRLF adds 0D 0A. For binary protocols, choose No line ending. Each send shows in the log as TX with the exact bytes, and the exported CSV carries a column with the raw hex of each entry, handy for pasting into another analyzer or a test.

Bytes and how they go in

Hex with spaces

Input: 48 65 6C 6C 6F
Expected output: Hello

Five bytes, no line ending.

Hex with 0x and commas

Input: 0x41,0x42
Expected output: 41 42 (AB)

The prefix and comma are ignored.

Text with an accent

Input: ç
Expected output: C3 A7

UTF-8 uses two bytes for this character.

Single-byte escape

Input: caf\xE9
Expected output: 63 61 66 E9

The \xE9 goes out as one byte, E9.

Hex with CRLF

Input: 41 + CRLF
Expected output: 41 0D 0A

The line ending goes after the typed bytes.

Full tool FAQ

What is Web Serial and which browsers have it?

It is an API that lets a page access serial ports with your permission. Per caniuse on 2026-11-02, it works in Chrome and Edge 89 or newer, Opera 76 or newer, Firefox on desktop from version 151 and Chrome for Android from 156. It does not work in Safari, on iPhone, in Firefox for Android or in Samsung Internet.

How do I connect an Arduino or an ESP board?

Which baud rate should I use?

What does 8N1 mean?

Why does it not work on iPhone, Safari or older Firefox?

Which line ending should I choose when sending?

How do I send bytes in hexadecimal?

Does the log grow without limit?

What if I pull the cable mid-session?

Is it safe? Does my data go to a server?

Frequently asked questions

Why does my hex have one digit too few?

Each byte needs two digits. A lone 4 is ambiguous, so type 04. The tool warns when the digit total is odd instead of guessing.

How do I view packets with no line breaks?

In Port options, switch Split incoming data to As it arrives, before connecting. Each browser read becomes one entry, without waiting for a terminator, and the Hex view shows those blocks as they came.

What is the byte order for numbers larger than one byte?

The tool does not interpret: it shows and sends bytes in the order they pass through the port. If the protocol uses little-endian, the number 0x1234 appears as 34 12. To convert values, use the base converter.

Next steps

Bytes, text and the three ways to send

In binary protocols, a byte such as 0x00 or 0xFF is not text. The Hex view shows each byte as two uppercase digits separated by a space, and the column beside it replaces anything not printable with a dot, the classic dump format. The line ends where the device sent LF, CRLF or CR, and the tool shows the terminator in the hex: 48 69 0D 0A is the word Hi followed by CRLF.

There are three ways to send. In Text mode, the input goes out as UTF-8, so ç sends C3 A7. With the escapes option on, \n, \r, \t and \0 become their bytes and \xNN sends an arbitrary byte: caf\xE9 sends 63 61 66 E9, with a byte that is not UTF-8. In Hex mode, the input accepts 48 65 6C, 0x48,0x65,0x6C, 48:65:6C or 48656C, and warns if a digit is missing or an invalid character appears.

The chosen line ending is added after the bytes in any mode: LF adds 0A, CR adds 0D, CRLF adds 0D 0A. For binary protocols, choose No line ending. Each send shows in the log as TX with the exact bytes, and the exported CSV carries a column with the raw hex of each entry, handy for pasting into another analyzer or a test.

Bytes and how they go in

Hex with spaces

Input: 48 65 6C 6C 6F
Expected output: Hello

Five bytes, no line ending.

Hex with 0x and commas

Input: 0x41,0x42
Expected output: 41 42 (AB)

The prefix and comma are ignored.

Text with an accent

Input: ç
Expected output: C3 A7

UTF-8 uses two bytes for this character.

Single-byte escape

Input: caf\xE9
Expected output: 63 61 66 E9

The \xE9 goes out as one byte, E9.

Hex with CRLF

Input: 41 + CRLF
Expected output: 41 0D 0A

The line ending goes after the typed bytes.

Full tool FAQ

What is Web Serial and which browsers have it?

How do I connect an Arduino or an ESP board?

Which baud rate should I use?

What does 8N1 mean?

Why does it not work on iPhone, Safari or older Firefox?

Which line ending should I choose when sending?

How do I send bytes in hexadecimal?

Does the log grow without limit?

What if I pull the cable mid-session?

Is it safe? Does my data go to a server?

Frequently asked questions

Why does my hex have one digit too few?

Each byte needs two digits. A lone 4 is ambiguous, so type 04. The tool warns when the digit total is odd instead of guessing.