ApproveIt for Slack - Get approvals in minutes, not days. Right from Slack!
LucidChart - LucidChart is the missing link in online productivity suites. LucidChart allows users to create, collaborate on, and publish attractive flowcharts and other diagrams from a web browser.
AccessOwl - Discover Shadow IT, Automate Access Reviews and Auto-Provisioning — No Enterprise-Subscriptions required.
draw.io - Online diagramming application
Approve app for Zendesk - Any enforceable and auditable approval workflow for Zendesk tickets you can imagine can be easily created using the Approve app.
yEd - yEd is a free desktop application to quickly create, import, edit, and automatically arrange diagrams. It runs on Windows, Mac OS X, and Unix/Linux.