Gantt diagram (Mermaid)

A Gantt chart is only worth drawing when it has dependencies. This one uses after to chain tasks, marks the critical work, and puts a zero-length milestone at the cutover.

#What this example shows

after, which makes a task start when another finishes.
crit, done and active, which mark status without a separate legend.
A milestone, which is a task with zero duration.

#A worked example

Open it, edit it, or copy the source below.

The source, which you can paste into a new diagram and edit:

gantt
  title Platform migration
  dateFormat YYYY-MM-DD
  axisFormat %d %b
  excludes weekends

  section Preparation
  Inventory current system   :done, inv, 2026-09-01, 10d
  Agree target architecture  :active, arch, after inv, 7d
  Provision environment      :prov, after arch, 5d

  section Migration
  Migrate reference data     :crit, ref, after prov, 5d
  Migrate transactional data :crit, data, after ref, 14d
  Parallel run               :par, after data, 10d

  section Cutover
  Freeze and switch          :milestone, cut, after par, 0d
  Monitor                    :mon, after cut, 5d
  Decommission old system    :dec, after mon, 5d

#Making it your own

excludes weekends keeps the dates honest for work that does not happen at weekends.
Mark the critical path with crit, or every bar looks equally important.
Keep it coarse. Sixty rows is a project plan nobody will read.

Pie chart (Mermaid)

Three slices, which is where a pie still works.

Mindmap (Mermaid)

A map generated purely from indentation.

Mermaid examples

Back to the rest of these examples.

Copy it. Change one line. See what happens.