Google App Engine - A powerful platform to build web and mobile apps that scale automatically.
draw.io - Online diagramming application
Dokku - Docker powered mini-Heroku in around 100 lines of Bash
LucidChart - LucidChart is the missing link in online productivity suites. LucidChart allows users to create, collaborate on, and publish attractive flowcharts and other diagrams from a web browser.
Google Cloud Functions - A serverless platform for building event-based microservices.
PlantUML - PlantUML is an open-source tool that uses simple textual descriptions to draw UML diagrams.