Full Karabiner-Elements setup with command+control+option+shift app switching. As featured on https://medium.com/p/85837748fc.

karabiner.json

{
    "global": {
        "check_for_updates_on_startup": true,
        "show_in_menu_bar": false,
        "show_profile_name_in_menu_bar": false
    },
    "profiles": [
        {
            "complex_modifications": {
                "parameters": {
                    "basic.simultaneous_threshold_milliseconds": 50,
                    "basic.to_delayed_action_delay_milliseconds": 500,
                    "basic.to_if_alone_timeout_milliseconds": 1000,
                    "basic.to_if_held_down_threshold_milliseconds": 500,
                    "mouse_motion_to_scroll.speed": 100
                },
                "rules": [
                    {
                        "description": "Change caps_lock to command+control+option+shift.",
                        "manipulators": [
                            {
                                "from": {
                                    "key_code": "caps_lock",
                                    "modifiers": {
                                        "optional": [
                                            "any"
                                        ]
                                    }
                                },
                                "to": [
                                    {
                                        "key_code": "left_shift",
                                        "modifiers": [
                                            "left_command",
                                            "left_control",
                                            "left_option"
                                        ]
                                    }
                                ],
                                "type": "basic"
                            }
                        ]
                    },
                    {
                        "description": "ccos + s to open Slack.",
                        "manipulators": [
                            {
                                "from": {
                                    "key_code": "s",
                                    "modifiers": {
                                        "mandatory": [
                                            "shift",
                                            "control",
                                            "command",
                                            "option"
                                        ]
                                    }
                                },
                                "to": [
                                    {
                                        "shell_command": "open -a /Applications/Slack.app"
                                    }
                                ],
                                "type": "basic"
                            }
                        ]
                    },
                    {
                        "description": "ccos + v to open VSCode.",
                        "manipulators": [
                            {
                                "from": {
                                    "key_code": "v",
                                    "modifiers": {
                                        "mandatory": [
                                            "shift",
                                            "control",
                                            "command",
                                            "option"
                                        ]
                                    }
                                },
                                "to": [
                                    {
                                        "shell_command": "open -a '/Applications/Visual Studio Code.app'"
                                    }
                                ],
                                "type": "basic"
                            }
                        ]
                    },
                    {
                        "description": "ccos + l to open Linear.",
                        "manipulators": [
                            {
                                "from": {
                                    "key_code": "l",
                                    "modifiers": {
                                        "mandatory": [
                                            "shift",
                                            "control",
                                            "command",
                                            "option"
                                        ]
                                    }
                                },
                                "to": [
                                    {
                                        "shell_command": "open -a '/Users/theo/Applications/Brave Browser Apps.localized/Linear.app'"
                                    }
                                ],
                                "type": "basic"
                            }
                        ]
                    },
                    {
                        "description": "ccos + 2 to open WhatsApp.",
                        "manipulators": [
                            {
                                "from": {
                                    "key_code": "2",
                                    "modifiers": {
                                        "mandatory": [
                                            "shift",
                                            "control",
                                            "command",
                                            "option"
                                        ]
                                    }
                                },
                                "to": [
                                    {
                                        "shell_command": "open -a /Applications/WhatsApp.app"
                                    }
                                ],
                                "type": "basic"
                            }
                        ]
                    },
                    {
                        "description": "ccos + c to open Cron.",
                        "manipulators": [
                            {
                                "from": {
                                    "key_code": "c",
                                    "modifiers": {
                                        "mandatory": [
                                            "shift",
                                            "control",
                                            "command",
                                            "option"
                                        ]
                                    }
                                },
                                "to": [
                                    {
                                        "shell_command": "open -a /Applications/Cron.app"
                                    }
                                ],
                                "type": "basic"
                            }
                        ]
                    },
                    {
                        "description": "ccos + r to open Reminders.",
                        "manipulators": [
                            {
                                "from": {
                                    "key_code": "r",
                                    "modifiers": {
                                        "mandatory": [
                                            "shift",
                                            "control",
                                            "command",
                                            "option"
                                        ]
                                    }
                                },
                                "to": [
                                    {
                                        "shell_command": "open -a \"/System/Applications/Reminders.app\""
                                    }
                                ],
                                "type": "basic"
                            }
                        ]
                    },
                    {
                        "description": "ccos + w to open Brave.",
                        "manipulators": [
                            {
                                "from": {
                                    "key_code": "w",
                                    "modifiers": {
                                        "mandatory": [
                                            "shift",
                                            "control",
                                            "command",
                                            "option"
                                        ]
                                    }
                                },
                                "to": [
                                    {
                                        "shell_command": "open -a '/Applications/Brave Browser.app'"
                                    }
                                ],
                                "type": "basic"
                            }
                        ]
                    },
                    {
                        "description": "ccos + f to open Finder.",
                        "manipulators": [
                            {
                                "from": {
                                    "key_code": "f",
                                    "modifiers": {
                                        "mandatory": [
                                            "shift",
                                            "control",
                                            "command",
                                            "option"
                                        ]
                                    }
                                },
                                "to": [
                                    {
                                        "shell_command": "open -a '/System/Library/CoreServices/Finder.app'"
                                    }
                                ],
                                "type": "basic"
                            }
                        ]
                    },
                    {
                        "description": "ccos + t to open Alacrityy.",
                        "manipulators": [
                            {
                                "from": {
                                    "key_code": "t",
                                    "modifiers": {
                                        "mandatory": [
                                            "shift",
                                            "control",
                                            "command",
                                            "option"
                                        ]
                                    }
                                },
                                "to": [
                                    {
                                        "shell_command": "open -a '/Applications/Alacritty.app'"
                                    }
                                ],
                                "type": "basic"
                            }
                        ]
                    },
                    {
                        "description": "ccos + e to open Spark.",
                        "manipulators": [
                            {
                                "from": {
                                    "key_code": "e",
                                    "modifiers": {
                                        "mandatory": [
                                            "shift",
                                            "control",
                                            "command",
                                            "option"
                                        ]
                                    }
                                },
                                "to": [
                                    {
                                        "shell_command": "open -a '/Applications/Spark.app'"
                                    }
                                ],
                                "type": "basic"
                            }
                        ]
                    },
                    {
                        "description": "ccos + m to open Spotify.",
                        "manipulators": [
                            {
                                "from": {
                                    "key_code": "m",
                                    "modifiers": {
                                        "mandatory": [
                                            "shift",
                                            "control",
                                            "command",
                                            "option"
                                        ]
                                    }
                                },
                                "to": [
                                    {
                                        "shell_command": "open -a '/Applications/Spotify.app'"
                                    }
                                ],
                                "type": "basic"
                            }
                        ]
                    },
                    {
                        "description": "ccos + n to open Craft.",
                        "manipulators": [
                            {
                                "from": {
                                    "key_code": "n",
                                    "modifiers": {
                                        "mandatory": [
                                            "shift",
                                            "control",
                                            "command",
                                            "option"
                                        ]
                                    }
                                },
                                "to": [
                                    {
                                        "shell_command": "open -a /Applications/Craft.app"
                                    }
                                ],
                                "type": "basic"
                            }
                        ]
                    },
                    {
                        "description": "ccos + d to open Figma.",
                        "manipulators": [
                            {
                                "from": {
                                    "key_code": "d",
                                    "modifiers": {
                                        "mandatory": [
                                            "shift",
                                            "control",
                                            "command",
                                            "option"
                                        ]
                                    }
                                },
                                "to": [
                                    {
                                        "shell_command": "open -a '/Applications/Figma.app'"
                                    }
                                ],
                                "type": "basic"
                            }
                        ]
                    },
                    {
                        "description": "ccos + p to open PGAdmin.",
                        "manipulators": [
                            {
                                "from": {
                                    "key_code": "p",
                                    "modifiers": {
                                        "mandatory": [
                                            "shift",
                                            "control",
                                            "command",
                                            "option"
                                        ]
                                    }
                                },
                                "to": [
                                    {
                                        "shell_command": "open -a '/Applications/pgAdmin 4.app'"
                                    }
                                ],
                                "type": "basic"
                            }
                        ]
                    }
                ]
            },
            "devices": [],
            "fn_function_keys": [
                {
                    "from": {
                        "key_code": "f1"
                    },
                    "to": [
                        {
                            "consumer_key_code": "display_brightness_decrement"
                        }
                    ]
                },
                {
                    "from": {
                        "key_code": "f2"
                    },
                    "to": [
                        {
                            "consumer_key_code": "display_brightness_increment"
                        }
                    ]
                },
                {
                    "from": {
                        "key_code": "f3"
                    },
                    "to": [
                        {
                            "key_code": "mission_control"
                        }
                    ]
                },
                {
                    "from": {
                        "key_code": "f4"
                    },
                    "to": [
                        {
                            "key_code": "launchpad"
                        }
                    ]
                },
                {
                    "from": {
                        "key_code": "f5"
                    },
                    "to": [
                        {
                            "key_code": "illumination_decrement"
                        }
                    ]
                },
                {
                    "from": {
                        "key_code": "f6"
                    },
                    "to": [
                        {
                            "key_code": "illumination_increment"
                        }
                    ]
                },
                {
                    "from": {
                        "key_code": "f7"
                    },
                    "to": [
                        {
                            "consumer_key_code": "rewind"
                        }
                    ]
                },
                {
                    "from": {
                        "key_code": "f8"
                    },
                    "to": [
                        {
                            "consumer_key_code": "play_or_pause"
                        }
                    ]
                },
                {
                    "from": {
                        "key_code": "f9"
                    },
                    "to": [
                        {
                            "consumer_key_code": "fast_forward"
                        }
                    ]
                },
                {
                    "from": {
                        "key_code": "f10"
                    },
                    "to": [
                        {
                            "consumer_key_code": "mute"
                        }
                    ]
                },
                {
                    "from": {
                        "key_code": "f11"
                    },
                    "to": [
                        {
                            "consumer_key_code": "volume_decrement"
                        }
                    ]
                },
                {
                    "from": {
                        "key_code": "f12"
                    },
                    "to": [
                        {
                            "consumer_key_code": "volume_increment"
                        }
                    ]
                }
            ],
            "name": "Default profile",
            "parameters": {
                "delay_milliseconds_before_open_device": 1000
            },
            "selected": true,
            "simple_modifications": [
                {
                    "from": {
                        "key_code": "non_us_backslash"
                    },
                    "to": [
                        {
                            "key_code": "escape"
                        }
                    ]
                }
            ],
            "virtual_hid_keyboard": {
                "country_code": 0,
                "indicate_sticky_modifier_keys_state": true,
                "mouse_key_xy_scale": 100
            }
        }
    ]
}