When you open the app, the previous JSON you used is still there and the cursor is focussed inside the editor. However, I often find myself pasting the JSON i'd like to format before the JSON that was already there, because the JSON isn't selected yet.
Right now, the flow of formatting a JSON structure is:
Open json.pizza
Select all (CMD+A)
Delete (backspace)
Paste new JSON (CMD+V)
Hit format (CMD+Enter)
I'd argue that the flow should be
Open json.pizza
Paste new JSON (CMD+V)
Hit format (CMD+Enter)
We can achieve this while maintaining the persistance feature by pre-selecting all the JSON in the editor when opening the app
rijkvanzanten
commented
4 years ago 
When you open the app, the previous JSON you used is still there and the cursor is focussed inside the editor. However, I often find myself pasting the JSON i'd like to format before the JSON that was already there, because the JSON isn't selected yet.
Right now, the flow of formatting a JSON structure is:
I'd argue that the flow should be
We can achieve this while maintaining the persistance feature by pre-selecting all the JSON in the editor when opening the app