InfraNodus - Generates research insights using text network visualization and analysis.
draw.io - Online diagramming application
arXiv - arXiv is a free distribution service and an open-access archive for scholarly articles.
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.
Unpaywall - Legally read research papers behind paywalls.
PlantUML - PlantUML is an open-source tool that uses simple textual descriptions to draw UML diagrams.