Readability

Export your Readability data

On the tools (https://www.readability.com/tools/) page, click on "Export your data" in the "Data Export" section. You will receive an email to download a json (which does not end with .json in fact).

Import your data into wallabag

Click on Import link in the menu, on Import contents in Readability section and then select your json file and upload it.

Your data will be imported. Data import can be a demanding process for your server.