Google Tag Manager - Google Tag Manager helps make tag management simple, easy and reliable by allowing marketers and webmasters to deploy website tags all in one place.
draw.io - Online diagramming application
Segment - We make customer data simple.
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.
RudderStack - Open-Source Customer Data Platform
PlantUML - PlantUML is an open-source tool that uses simple textual descriptions to draw UML diagrams.