~/.config/karabiner/assets/complex_modifications/

customed.json

{
  "title": "Customed",
  "rules": [
    {
      "description": "Post caps_lock if fn is pressed alone",
      "manipulators": [
        {
          "type": "basic",
          "from": {
            "key_code": "fn",
            "modifiers": {
              "optional": ["any"]
            }
          },
          "to": [
            {
              "key_code": "fn"
            }
          ],
          "to_if_alone": [
            {
              "key_code": "caps_lock"
            }
          ]
        }
      ]
    },
    {
      "description": "Post escape if left_control is pressed alone",
      "manipulators": [
        {
          "type": "basic",
          "from": {
            "key_code": "left_control",
            "modifiers": {
              "optional": ["any"]
            }
          },
          "to": [
            {
              "key_code": "left_control"
            }
          ],
          "to_if_alone": [
            {
              "key_code": "escape"
            }
          ]
        }
      ]
    },
    {
      "description": "Post up_arrow if right_shift is pressed alone",
      "manipulators": [
        {
          "type": "basic",
          "from": {
            "key_code": "right_shift",
            "modifiers": {
              "optional": ["any"]
            }
          },
          "to": [
            {
              "key_code": "right_shift"
            }
          ],
          "to_if_alone": [
            {
              "key_code": "up_arrow"
            }
          ],
          "to_if_held_down": [
            {
              "key_code": "up_arrow"
            }
          ],
          "parameters": {
            "basic.to_if_held_down_threshold_milliseconds": 150
          }
        }
      ]
    },
    {
      "description": "Control+Command+Delete to start Screen Saver",
      "manipulators": [
        {
          "type": "basic",
          "from": {
            "key_code": "delete_forward",
            "modifiers": {
              "mandatory": ["control", "command"]
            }
          },
          "to": [
            {
              "shell_command": "open -a ScreenSaverEngine.app"
            }
          ]
        }
      ]
    },
    {
      "description": "Left ctrl + hjkl to arrow keys Vim",
      "manipulators": [
        {
          "consitions": [
            {
              "type": "frontmost_application_unless",
              "bundle_identifiers": ["^com\\.googlecode\\.iterm2$"]
            }
          ],
          "from": {
            "key_code": "h",
            "modifiers": {
              "mandatory": ["left_control"],
              "optional": ["any"]
            }
          },
          "to": [
            {
              "key_code": "left_arrow"
            }
          ],
          "type": "basic"
        },
        {
          "from": {
            "key_code": "j",
            "modifiers": {
              "mandatory": ["left_control"],
              "optional": ["any"]
            }
          },
          "to": [
            {
              "key_code": "down_arrow"
            }
          ],
          "type": "basic"
        },
        {
          "from": {
            "key_code": "k",
            "modifiers": {
              "mandatory": ["left_control"],
              "optional": ["any"]
            }
          },
          "to": [
            {
              "key_code": "up_arrow"
            }
          ],
          "type": "basic"
        },
        {
          "consitions": [
            {
              "type": "frontmost_application_unless",
              "bundle_identifiers": ["^com\\.googlecode\\.iterm2$"]
            }
          ],
          "from": {
            "key_code": "l",
            "modifiers": {
              "mandatory": ["left_control"],
              "optional": ["any"]
            }
          },
          "to": [
            {
              "key_code": "right_arrow"
            }
          ],
          "type": "basic"
        }
      ]
    },
    {
      "description": "Tab to HYPER (SHIFT+COMMAND+OPTION+CONTROL) or Tab (If Alone)",
      "manipulators": [
        {
          "from": {
            "key_code": "tab",
            "modifiers": {}
          },
          "to": [
            {
              "key_code": "left_shift",
              "modifiers": ["left_command", "left_control", "left_option"]
            }
          ],
          "to_if_alone": [
            {
              "key_code": "tab"
            }
          ],
          "type": "basic"
        }
      ]
    }
  ]
}