Binary Notepad Developer
A hex editor in the browser: open any file, see it as hex, binary or decimal next to the text, edit bytes, insert and delete, search and save.
Binary Notepad is a free online tool that a hex editor in the browser: open any file, see it as hex, binary or decimal next to the text, edit bytes, insert and delete, search and save. It runs entirely in your web browser using plain JavaScript, so files are processed on your own device and never uploaded to a server. There is no sign-up, no file size limit imposed by the site, no watermark and no paid tier.
- Price
- Free: no account, no quota, no watermark
- Category
- Developer
- Where it runs
- In your browser, on your device
- Files uploaded
- None
- Technology
- plain JavaScript
- Settings
- 5
- Works offline
- Yes, after the first visit
About Binary Notepad
Every file is just bytes, and this shows them: an offset column, the bytes in hex (or binary, or decimal), and the same bytes as text on the right. Click a byte and type to overwrite it, switch to insert mode to add or remove bytes, and the changes are colored until you save. A data inspector reads the bytes at the cursor as signed and unsigned integers, 32-bit and 64-bit floats and a UTF-8 character, which is how you make sense of a file header. Only the rows on screen are rendered, so a file of many megabytes scrolls smoothly. Start from an empty buffer to write a file from scratch, paste text or hex to add many bytes at once, and save the result as a download.
How to use it
- Press "Open" to load a file, or "New" for an empty buffer. Drop a file anywhere on the page too.
- Click a byte in the hex column or the text column and type. Arrow keys move, Tab switches columns, Insert toggles insert and overwrite mode.
- Search for text or hex bytes, jump to an offset, and read the values at the cursor in the inspector below.
- Press "Save" (or Ctrl+S) to download the edited bytes under the name you set.
The 5 settings
| Setting | What it does | Default |
|---|---|---|
| Insert or Overwrite | Insert adds bytes as you type and lets Backspace and Delete remove them; Overwrite replaces bytes in place. | Insert for a new buffer, Overwrite for an opened file |
| Show | Hex, Binary or Decimal for the byte column. | Hex |
| Bytes per row | 8, 16, 24 or 32. | 16 |
| Name | The file name used when saving. | untitled.bin |
| Search as hex | On or off. On treats the search box as hex bytes; off searches for UTF-8 text. | Off |
Under the hood
| Runs on | plain JavaScript: a typed array holds the bytes, DataView reads them for the inspector, and only the visible rows are rendered |
| Controls | Insert or Overwrite, Show, Bytes per row, Name, Search as hex |
Questions
How do I edit in binary?
Switch "Show" to Binary. Each byte is shown as eight bits, and typing 0 or 1 sets the bits from left to right. Hex is faster for most edits; binary is there for flag fields.
What does the inspector show?
The bytes starting at the cursor read as int8, uint8, int16, uint16, int32 and uint32 (little-endian, with big-endian variants for the signed 16 and 32-bit values), float32, float64 and the UTF-8 character. Little-endian is what x86 and ARM files use; big-endian is common in network protocols and older formats.
How large a file can it open?
The file is held in memory as a typed array, so anything your device can spare, typically hundreds of megabytes on a laptop. Only the visible rows are drawn, so scrolling and searching stay quick.
Can I search for a hex pattern?
Yes. Tick "Hex" next to the search box and type bytes such as 4D 5A or 0x89504E47; spaces and 0x prefixes are ignored. Untick it to search for text, which is matched as UTF-8 bytes.
Will it change my file in ways I did not type?
No. Every byte you did not touch is written back exactly as it was read, including line endings and anything after a null byte. Changed bytes are highlighted until you save.
Is anything uploaded?
No. The file is read by your browser into memory and never sent anywhere; saving is a download of that memory.
Can I use it full screen, or keep a copy offline?
Yes to both. "Full screen" above the tool fills the whole screen (Esc leaves it). "Save as HTML" writes this one tool to a single self-contained file that opens from your own disk without a connection. For everything at once there is a desktop app for Windows, macOS and Linux with all 312 tools inside it.