Sure, Lucidchart is awesome.

But have you considered these open source alternatives?

They are free, self-hostable and community-driven.

Check by yourself: Excalidraw , D2 , tldraw , Draw.io , Mermaid Live Editor .

So is Excalidraw

Доска для рисования диаграмм от руки
★ 130K Diagram Whiteboard License: MIT
Виртуальная доска с рукописным стилем с открытым исходным кодом. Совместная работа и сквозное шифрование.

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So is D2

Turn text into diagrams
★ 25K Diagram License: MPL-2.0
A modern diagram scripting language that turns text to diagrams.

Read more about D2
So is tldraw

Digital whiteboard with infinite canvas
★ 49.9K Diagram License: MIT
Tldraw is a library for creating infinite canvas experiences in React. It's the software behind the digital whiteboard tldraw.com.

Read more about tldraw
So is Draw.io

JavaScript, client-side editor for general diagramming
★ 62.7K Diagram License: Apache-2.0
Browser-based diagramming components and applications.

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So is Mermaid Live Editor

Редактируйте, просматривайте и делитесь диаграммами/схемами mermaid
★ 6.8K Diagram License: MIT
Редактируйте, просматривайте и делитесь диаграммами/схемами mermaid.

Read more about Mermaid Live Editor