Keymap Editor
http://www.tmk-kbd.com/tmk_keyboard/editor/
With Keymap Editor you can edit your keymap and download Unimap firmware. Unimap firmware is comprised of execution code part and keymap data. Execution code part is specific to device while keymap data is universal can be used with all devices supported by TMK. Keymap Editor keeps excution code part untouched.
The keymap data is placed at the end of available flash memory region. Unimap firmware of ATMega32U4 with 32KB flash looks like below for example.
+------------+ 0x0000
| |
| |
| | > Execution code region
| |
| |
|------------| 0x6800
| .keymap | > Keymap region(2KB)
+------------+ 0x7000
You can select Editor template which suits for your keyboard.
Use 'Raw URL' or 'URL Shortener' button to get URL of keymap editor and bookmark it. Short URL would be useful to share with others.
Just download and put aside your firmware HEX file for later use.
You can edit keymap of your own firmware file on Editor. You can supply firmware file by URL or uploading HEX file from local storage.
Click 'Load Keymap from firmware' button to load keymap on Editor from your firmware. You can start editting from your stored keymap instead of default.
https://www.youtube.com/watch?v=TYmAb8zOPWU&feature=youtu.be&t=10m59s
https://www.youtube.com/watch?v=TYmAb8zOPWU&feature=youtu.be&t=14m0s