When I was looking into gathering some information on my posts, I found Ghost has a ready-to-go JSON REST API readily available. To use it, you must first enable it in settings:
Then it is as simple as requesting this URL
https://YOUR_DOMAIN/ghost/api/v0.1/posts/?client_id=ghost-frontend&client_secret=xxxxxxxxxx. The domain and the client secret will change from installation to installation. The 'client secret' is publically available on all Ghost pages. You can find it by viewing the source of any Ghost generated page or by looking in the database of your Ghost installation.
Below, I've included a quick example using Axios and React using this URL. I've also included the limit option as Ghost by default only returns the first page of results.