iZap - piZap Photo Editor is fun and easy to learn online photo editor & collage maker. Tons of effects, fonts, stickers, collage layouts, borders, frames, and editing tools.
SocialSizes - Sketch templates for sharing images & videos on social media
Bazaart - Create. Discover. Love. Social photo collage editor
Invision - Prototyping and collaboration for design teams
PhotoRoom - Create studio-quality product pictures in seconds.
Craftwork - A collection of User Interface resources made by Craftwork