Antconc - The website of Laurence Anthony. Professor at Waseda University Japan, developer of AntConc, a freeware concordancer software program for Windows, Linux, and Macintosh OS X
draw.io - Online diagramming application
Voyant Tools - Voyant Tools is a web-based reading and analysis environment for digital texts.
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.
TextSTAT - TextSTAT is a simple programme for the analysis of texts.
PlantUML - PlantUML is an open-source tool that uses simple textual descriptions to draw UML diagrams.