When comparing Prototyping on Paper vs Noodl, the Slant community recommends Noodl for most people. In the question“What are the best tools for prototyping mobile interactions/animations?” Noodl is ranked 11th while Prototyping on Paper is ranked 20th. The most important reason people chose Noodl is:
You can use REST API to get data to your prototype.
Ranked in these QuestionsQuestion Ranking
Pros
Pro Multiple device support
Prototyping on Paper supports both Android and iOS.
Pro Based on sketched wireframes
Prototypes made on PoP are based on sketches made on paper or a whiteboard, which are later photographed or scanned and uploaded into the app. Once that's done, hotspots can then be added, which register tapping or several gestures.

Pro Use external data
You can use REST API to get data to your prototype.

Pro Free

Pro Cross-platform
It is a Chrome app and you can test prototypes on any device that supports WebGL or Canvas.

Pro Prototype two-device (master — companion) apps
You can setup communication between two devices.

Pro Components
You can build one interactive component and then reuse it with different input values (like images, txt, width, speed — any value you can imagine).
Cons
Con Not well suited for complex prototypes
PoP is built to be a tool for quick prototyping, especially in participatory design sessions. For complex prototypes with a lot of screens it would require a large number of images to be used and this can make any project hard to maintain.
