XMind

Open Source

FreeMind

Java-based desktop app
Features:
main : a hierarchical editor that emphasizes folding
Distraction free writing
Mind Map view
Simple installation
Brainstorming
Hierarchical structure
Knowledge Management
Minimap
Works Offline
Shortcut keys

Freeplane

Extensible, multi-platform mind mapping creation, analysis and presentation software.
Features:
Conditional stylesKnowledge ManagementSupport for LaTeXPortableScriptingShared NodesSummary Nodes

TreeSheets

A “hierarchical spreadsheet” that is a great replacement for spreadsheets, mind mappers, outliners, PIMs, text editors and small databases.

rejected

Lucidchart

cloud based
community versus professional

Mindomo

Freemium
TabletiPadChromeSafariSoftware as a Service (SaaS)Firefox
a simple yet powerful mindmapping tool that supports brainstorming, presentation and collaboration .
Features:
Built-in Note TakerBackup to Google DriveBrainstormingCloud syncCustom templatesGantt-chartsGoogle Drive integrationGroup chatHierarchical structureIcon setsOnline collaborationOutlinerPassword encryptionReal time collaborationExport to PDFSorting by folderTask ManagementVisual-thinkingYoutube integration