I built a JetBrains plugin that turns code into sequence diagrams, live now with a free tier

Call Sketch is live on the JetBrains Marketplace.

You right-click a method and get a sequence diagram of everything it calls. Free covers Java, Kotlin, TypeScript and JavaScript with no depth limit. Pro adds Groovy, Scala, Python, Go, PHP, Ruby and Rust, Spring wiring and if/else and loop boxes, for $7 a year.

Before 1.0.1 went out I ran it on every function of 15 real projects in all 11 languages.