Short answer: yes it is
Long answer: there are quite a few ways to achieve that. You can create a custom plugin with a custom element type to create a list just like the normal entries in craft filled with your data. You can then - during the saving process - update the data with your api to sync it with whatever you want.
If you are kind of lazy you could just create a normal section for your entries with all the required fields from your api and create a cronjob/task/function to download/fetch all entries with your api and hook into a
onBeforeSaveEntry to validate the data and upload it to your api.
So all in all yes. It's relative easy and can be done in quite a few hours/days once you get used to Craft because the CMS does many things for you. It renders all lists/forms and manages the entire saving, sorting, filtering and searching processes for you. You just have to import the data (easy thing) and export the data. If you require some special sort validations you can include those rules too and Craft displays all errors