Flowchart and diagram software

If you mean “best overall for most people,” I’d pick lucid.co.

But the right choice depends heavily on what you’re diagramming:

• lucid.co — Best overall: polished, easy to learn, strong flowcharts/process maps, collaboration, data-driven diagrams, UML, and AI-assisted diagramming.Lucid Software+1
• miro.com — Best for teams/brainstorming: excellent if diagrams are part of workshops, product planning, mind maps, user journeys, or collaborative whiteboarding. It also supports UML, ERDs, BPMN, cloud architecture, and AI-generated diagrams.Miro+1
• microsoft.com — Best for Microsoft-heavy organizations: particularly strong for formal business/process diagrams and Microsoft 365/SharePoint environments, with both web and desktop apps.Microsoft Learn+1
• diagrams.net (draw.io) — Best free option: great if you want capable diagramming without paying for a full collaboration platform.
• Mermaid — Best for diagrams-as-code: excellent for software architecture, documentation, GitHub/Markdown workflows, and diagrams you want to generate from text.

My quick recommendation

If you tell me what kind of diagrams you make (software architecture, flowcharts, org charts, ERDs, network diagrams, business processes, presentations, etc.), I can narrow it down to the best 2–3 options for your use case.