Hex Editor

In overwrite mode, editing a byte replaces the existing byte at that position without changing the file size. This is the standard mode for most hex editing tasks like changing values, patching configurations, or fixing individual bytes. In insert mode, editing a byte inserts a new byte at that position and shifts all subsequent bytes one position to the right, increasing the file size by one byte. Insert mode is useful for adding data to a file, such as padding bytes, new header fields, or reconstructed data. You can also delete bytes in insert mode, which shifts remaining bytes left and decreases the file size.

You can edit absolutely any file type with this hex editor, including executables (.exe, .elf), images (.png, .jpg, .gif, .bmp), documents (.pdf, .docx), archives (.zip, .tar, .gz), audio/video files (.mp3, .mp4, .wav), firmware images, configuration files, and raw binary data. Since a hex editor operates at the byte level, it does not care about the file format - it simply shows you the raw bytes. However, editing certain file types without understanding their structure can corrupt the file, so always keep a backup.

Absolutely. All file processing is performed entirely within your browser using the FileReader API. Your files are never uploaded to any server, transmitted over the network, or stored in the cloud. You can verify this by checking your browser developer tools network tab - no requests are made when editing files. This makes the hex editor safe for editing proprietary binaries, personal documents, or any sensitive data that must remain private.

The hex editor currently does not have a multi-step undo history. However, you can click the Reset button at any time to restore the file to its original unmodified state as long as you have not cleared the editor. The original bytes are preserved in memory until you upload a new file or click Clear. For safety, always keep a backup copy of your original file before making edits, especially when working with important files.

Use the search bar in the toolbar to search for hex patterns or ASCII text. Type hex values without spaces (e.g., "FFD8FFE0" for a JPEG header) to find that byte sequence. You can also type plain text (e.g., "JFIF") to search for ASCII strings within the file. The search shows the number of matches and lets you navigate between them using the arrow buttons. Matched positions are highlighted in yellow in the hex dump.

The hex editor can handle files up to your browser available memory limit. Since the entire file is loaded into memory for editing, very large files (500MB+) may cause performance degradation or memory issues on devices with limited RAM. For most use cases - software binaries, documents, images, and configuration files - the hex editor handles files smoothly. The file size is displayed after upload so you can evaluate whether your device can handle it.

Modified bytes appear in red bold text to highlight your changes at a glance. The currently selected byte has a blue highlight ring. The byte being actively edited shows a blue background with a text input. Search results are highlighted in yellow. The color coding makes it easy to track what you have changed and navigate the file efficiently. The ASCII panel on the right also shows modified characters in red.

The hex editor supports full keyboard navigation for fast editing. Use the arrow keys (↑ ↓ ← →) to move between bytes. Press Tab to advance to the next byte and Shift+Tab to go back. Press Delete to zero out the current byte in overwrite mode, or delete it in insert mode. Press Escape to cancel an edit in progress. When editing, simply type two hex characters (0-9, A-F) and the byte is automatically applied. This keyboard-driven workflow makes the hex editor efficient for bulk editing tasks.