What do you mean by LiquidPlanner Classic and LiquidPlanner New?
LiquidPlanner Classic (app.liquidplanner.com) is the legacy online project management solution that launched in 2008. This documentation center supports the API for LiquidPlanner Classic.
LiquidPlanner New (next.liquidplanner.com) is the next generation, built on an ultra fast architecture that updates in real time as things change. LiquidPlanner New came out in April 2021 and its API was released in August 2022. Visit the API Guide for LiquidPlanner New to see what it offers.