DYNO Mapper - Create Sitemaps with the DYNO Mapper Visual Sitemap Generator.
draw.io - Online diagramming application
A1 Sitemap Generator - A1 Sitemap Generator has been in active development and sold since 2005.
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.
Site Visualizer Professional - Crawl website, visualize pages and links, analyze the structure of a website, build SEO reports with SQL
PlantUML - PlantUML is an open-source tool that uses simple textual descriptions to draw UML diagrams.