Top Free Diagramming Tools Every Engineer Should Know

1. Excalidraw

Excalidraw is an open‑source virtual whiteboard web application that lets you draw flowcharts, sketches, and other diagrams. It supports multiple languages (including Chinese), offers a hand‑drawn style, allows importing third‑party graphics, provides multi‑user collaboration, keyboard shortcuts, and can paste tables from Excel. Features include a clean interface, no registration required, end‑to‑end encryption, and sharing via a web link.

URL: https://excalidraw.com/

2. Zen Flowchart

Zen Flowchart is an English‑language online tool that is easy to use thanks to browser translation features. After a quick email registration you can log in and start creating diagrams. Its product features include online flowcharts, mind maps, low‑fidelity wireframes, a collaborative whiteboard, task management, and note‑taking.

URL: https://www.zenflowchart.com/

3. Visual Paradigm Online

Visual Paradigm Online provides a wide range of diagram templates that can be selected and used directly. It is a multifunctional design and drawing platform offering infographic editors, e‑book editors, chart editors, collage editors, and online creation of visual effects, UML, BPMN, and ArchiMate diagrams.

URL: https://online.visual-paradigm.com/cn/

4. draw.io (diagrams.net)

draw.io is a widely‑used online diagramming site that works across platforms (Windows, macOS, and browsers). It supports creating flowcharts, mind maps, network topologies, and many other diagram types.

URL: https://www.draw.io/ or https://www.diagrams.net/

draw.io can also be used to draw attractive network topology diagrams.

5. Liuchengtu (迅捷画图)

Liuchengtu offers many templates and a simple creation process, making it a strong domestic alternative. However, many templates require payment.

URL: https://www.liuchengtu.com/

6. ProcessOn

ProcessOn is an online collaborative drawing platform that provides powerful, easy‑to‑use tools for creating flowcharts, mind maps, org charts, network topologies, BPMN, UML diagrams, UI prototypes, and iOS prototypes. It enables real‑time collaboration and sharing over the internet.

URL: https://www.processon.com/

Which tool do you currently use, and do you have other recommendations?