Question: app to do picture collage?
Answer: Canva. This free app is perfect for people who want to create professional-looking collages but aren't good at graphic design. ... 
Diptic. Tired of the usual borders in your photo collages? ... 
Moldiv. ... 
PicStitch. ... 
Layout. ... 
Photo Grid. ... 
Pic Collage. ... 
Photo Blend & Shape Collage Maker.