Introduction

When participating in a workshop at iPRES (International Conference on Digital Preservation), the hex editor “HxD” was used for hands-on exercises in digital preservation. It is an essential tool in digital archive practice for tasks such as analyzing binary file structures and verifying file formats.

However, HxD is Windows-only and cannot be used on Mac. After the workshop, I searched for alternative tools to perform similar work in a Mac environment and found a web-based hex editor.

In this article, I introduce how to use the web-based hex editor “HexEd.it” in detail for Mac users. This guide enables you to practice what you learned with HxD at the iPRES workshop using HexEd.it.

What Is HxD? Why Can’t It Be Used on Mac?

HxD Hex Editor is a feature-rich hex editor for Windows. It is free and lightweight, making it popular among many developers and security researchers.

Key Features of HxD

  • Fast performance
  • Large file support
  • RAM editing capability
  • Disk editor functionality
  • Checksum calculation

However, HxD was developed as a Windows-only application and does not support macOS. While it is possible to run it using a virtual environment or Wine, this requires extra effort.

HexEd.it - A Browser-Based Alternative

As an alternative tool that works on Mac, there is HexEd.it (https://hexed.it/).

Features of HexEd.it

Cross-platform support

  • Works on any OS – Windows, Mac, Linux – as long as you have a browser
  • No installation required, ready to use immediately

Privacy-focused

  • Files are processed in the browser and are not uploaded to a server
  • Can also work offline

Rich features

  • Simultaneous Hex/ASCII display
  • Byte editing
  • Search and replace
  • File comparison
  • Data type conversion (int, float, etc.)
  • Export functionality

Free to use

  • Basic features are completely free

How to Use HexEd.it

1. Opening a File

  1. Access https://hexed.it/ in your browser
  2. Click the “Open file” button
  3. Select the file you want to edit

Alternatively, you can drag and drop a file onto the screen.

2. Understanding the Interface

The HexEd.it screen is divided into three main areas:

┌│├│││└────O─000──f─000──f─000──s─000──e─000──t─000───012───000─────────────┬│┼│││┴─────50E───08F──H───e─400──x─B01─────D─002──i─303──s───p─004──l─405──a───y─126───417──A───r─008──e─009──a────0AA───0BB──────0CC───0DD───────┬│┼│││┴─────P──A─K.──S─.#──C─..E──I─.!g──I─...───...──V─...──i─...──e─...──w─...───...───│││─┐│┤┘

Offset (left)

  • Displays position within the file in hexadecimal
  • Starts from 00000000

Hex Display Area (center)

  • Displays byte data in hexadecimal
  • Shows 16 bytes per line (default setting)

ASCII Display Area (right)

  • Displays bytes as characters
  • Printable characters are shown as-is; others are shown as “.”

3. Editing Data

Editing Bytes

  1. Click on the byte you want to edit
  2. Enter the new value in hexadecimal (e.g., FF, 00, 5A)
  3. Press Enter to confirm

Editing Multiple Bytes

  1. Drag to select the range you want to edit
  2. Select “Edit” from the right-click menu
  3. Enter the new values

4. Search Function

You can search for specific byte patterns or text.

Hex Search

  1. Select “Search” then “Find” from the top menu
  2. Select the “Hex” tab
  3. Enter the byte sequence to search for (e.g., FF D8 FF)
  4. Click “Find”

Text Search

  1. Select “Search” then “Find”
  2. Select the “Text” tab
  3. Enter the string to search for
  4. Select the encoding (UTF-8, ASCII, etc.)
  5. Click “Find”

5. Data Type Conversion

You can interpret selected bytes as various data types.

  1. Select bytes (e.g., 4 bytes)
  2. Check the “Inspector” panel at the bottom
  3. It displays in the following formats:
    • Int8 / Uint8 (1-byte integer)
    • Int16 / Uint16 (2-byte integer)
    • Int32 / Uint32 (4-byte integer)
    • Float (floating point)
    • Double (double precision floating point)

This is useful when analyzing the data structure of binary files.

6. File Comparison

You can check the differences between two files.

  1. Open the first file
  2. Select “Tools” then “Compare files”
  3. Select the second file to compare
  4. Differences are highlighted in red

7. Saving Files

Save the file after editing.

Overwrite Save

  • Select “File” then “Save”
  • The edited file is downloaded

Save As

  • Select “File” then “Export”
  • Specify a filename and save

Save Selection Only

  1. Select the range you want to save
  2. Right-click then “Export selection”
  3. Only the selected portion is saved as a file

Practical Use Cases

Example 1: Checking Image File Headers

When opening a JPEG file, the first bytes always start with FF D8 FF.

O0f0f0s0e0t000HFeFxD8FFE000104A464946ASCII.JFIF

This allows you to confirm whether a file is actually a JPEG.

Example 2: Checking Text File Encoding

You can determine the encoding from the leading bytes of a text file.

UTF-8 with BOM

EFBBBF

UTF-16 LE with BOM

FFFE

Example 3: Binary File Corruption Check

You can check for unnatural patterns in the middle of a file. For example, a ZIP file should start with:

504B0304←ZIPfilemagicnumber

Example 4: Simple File Modifications

This can be used when you want to change specific values in game save data or configuration files.

  1. Open the file
  2. Search for the position of the value you want to change
  3. Rewrite with the new value
  4. Save

Limitations of HexEd.it

HexEd.it has some limitations:

File Size Limitation

  • Depends on browser memory
  • Very large files (several GB) may not open
  • Less capable with large files compared to HxD

Offline Use

  • Internet connection required (for initial access)
  • Can be used offline if saved as a PWA (Progressive Web App)

Advanced Features

  • No RAM editor or disk editor functionality
  • Some advanced HxD features are not supported

Other Mac-Compatible Hex Editors

Besides HexEd.it, there are other hex editors available for Mac:

Desktop Applications

Hex Fiend (Free)

Synalyze It! (Paid/Free version available)

0xED (Free)

  • Open source
  • Basic hex editing features

Editor Extensions

Visual Studio Code + Hex Editor Extension

  • Easy to set up if you already use VS Code
  • Install the “Hex Editor” extension

Summary

HxD is Windows-only, but HexEd.it allows you to perform equivalent work on Mac.

Use cases for HexEd.it:

  • Mac users
  • When you want to use it without installation
  • When working across multiple OS environments
  • When privacy is important
  • When handling small to medium-sized files

Use cases for desktop applications:

  • When handling very large files
  • When working in an offline environment
  • When more advanced features are needed

Choose between HexEd.it, Hex Fiend, and other tools depending on your use case.

Reference links: