A module which allows addition of number of fields to the frontend checkout step. Module configuration can be found under the "Sales" section of the system configuration once installed and is labeled as "Checkout Fields".

Installation

Add this to your project dependecies list composer require extroniks/magento2-checkout-fields
Run bin/magento setup:upgrade
Run bin/magento setup:di:compile
Configure module in system configuration
Run bin/magneto cache:flush

Compatibility/Tested on:

Magento 2.2

Todos

Support for fields in billing section
Better styling/theme
Finish sorting implementation
Add validation support
More input types

For more information about the module take a look at the documentation