Mermaid where it fits, native Gantt where it does not

People search for “Mermaid Gantt” because they already have a gantt block in a repo. DiagramTool can open that file and convert it. The live Gantt tab still edits a native diagram: gantt document — dates, groups, assignees, and FS/SS/FF/SF dependencies — not a Mermaid live-preview of the original text.

Mermaid support, stated precisely

• Sequence: Mermaid sequenceDiagram is the editor format. See sequence from text.
• Flow: Mermaid flowchart / graph imports (and can be copied back out as Mermaid). The Flow tab’s everyday authoring language is the native DSL. See flowcharts from text.
• Gantt: File → Open detects a leading gantt line, converts sections/tasks into native DSL, then opens a Gantt board. Pasting Mermaid gantt into the Gantt editor is not the supported path — use diagram: gantt there, or import the file.
• Not opened: erDiagram, classDiagram, mindmap, state diagrams, pie, gitGraph, journey, quadrant, timeline, and Mermaid C4. Architecture C4 in this app is the native level: / parent: model, not those Mermaid diagrams.

Native Gantt you type in the editor

diagram: gantt
title: Launch plan
start: 2026-09-01

group "Build" {
  task Design {
    start: 2026-09-01
    end: 2026-09-05
    assignee: Design
    progress: 40
  }
  task Implement {
    start: 2026-09-05
    end: 2026-09-12
    depends: Design
  }
}

Tasks can declare depends: OtherTask:FS+2d (and SS/FF/SF). Groups nest visually. The Gantt surface includes a timeline and a board view, filters, resources, baselines, delay impact, and print/export helpers. Starter plans cover software delivery and a few other project shapes — they are templates, not a required methodology.

Mermaid gantt on disk

gantt
title Sprint Plan
dateFormat YYYY-MM-DD
section Build
Design :a1, 2026-08-01, 4d
Implement :after a1, 5d

Opening that file produces native tasks (and a group from the section name) so the rest of the Gantt UI can schedule and export. After import, what you edit is the native document. If you need to keep the original Mermaid in git, keep the .mmd as a source file and treat the workspace board as the working copy.

Export

Gantt export can write the chart from the Gantt SVG when the React Flow canvas is not on screen. PNG, SVG, and PDF are available without an export watermark on the free path. Architecture and flow boards share the same export family plus JSON backup and CSV.