Mulitsite Installations?

The free version can be used on multisites: Their limited features has no effects on this.
With the PRO-Version you can store Templates in the database for using it on multiple pages / blogentries. As these Templates are stored site by site multisite Management comes into the game. PRO-Versions prior to 2.0.9 do not support multisite. Versions after 2.0.9 are multisite ready.

Thanks to Rod from Canada and Layth from Australia!

Version 3.4.10 (December 4 2018), see in detail here:

bugfix 1: shortcode in widget-text of sidebar only if PHP < 7.2
bugfix 2: Improved fixing invalid JSON (shortcode parameter trytohealjson=yes together with parser=twig) - use this when an API delivers invalid JSON

Version 3.4.9 (August 31 2018), see in detail here:

pro plugin is ok with wordpress 3.4.9
pro plugin is ok with gutenberg plugin 3.6.2
added Information on General Data Protection Regulation (GDPR): see Plugin-Options Tab "GDPR"
added links to HowTo-Videos: https://json-content-importer.com/support/videos-on-json-content-importer/
creating custom post types: uniquekey can be placed in cpt-parameters as "key" - instead of custom fiel value ("jci_uniquekey_createpost")
new shortcode-parameter displayapireturn: put api-return as string into JSON and access via {{data}} (e.g. if api delivers raw encoded image-data). displayapireturn=1 (pass directly), displayapireturn=2 (pass base64_encoded), displayapireturn=4 (remove linefeeds)
if shortcode-parameter addpostdata2json=y then the array "jcipageparam" is added to the API-JSON to get access to the WP_Post OBJECT (get_post) like ID, post_date...
improved debugmode