Chris Nanney

Dev Toolbox

April 3, 2022

Dev Toolbox is a cross-browser extension that provides quick offline access to various development tools.

Dev Toolbox

For Microsoft Edge, extensions can be installed as-is from the Chrome Web Store.



  • Future changelog will be published on GitHub

v1.0.10May 16, 2022

  • Add button to pop out extension into a new window
  • Remember setting of GitHub Only emoji toggle
  • Improve build process for easier publishing

v1.0.5Apr 7, 2022

  • Updates for Firefox compatibility

v1.0.2Apr 4, 2022

  • Use Roboto Mono for consistent cross-platform sizing in tool output
  • Fix input select resize with delayed font loading

v1.0.0Apr 2, 2022

  • Initial release


Handy access to various tools
Calculate hashes; encode and decode HTML, URI, Base64; convert numbers between different bases; parse and manipulate various time formats; format and inspect IPv4/CIDR addresses; search all v13.1 emoji with quick copying in various formats.
No extra permissions required
It runs entirely offline, making no external requests (even emoji PNG files are bundled), and only uses local storage to remember your last tab and input.


Simple offline tools.
Simple offline tools.
Dark mode.
Dark mode.
Instant emoji search.
Instant emoji search.
Emoji details and quick copy.
Emoji details and quick copy.


This was inspired by an old extension called Hasher (no longer on the Chrome Store) that provided a simple interface to similar utilities. This was an opportunity to get back into making extensions, try out SvelteKit, and expand upon the original idea.

Please report any problems or suggestions here at GitHub.