Excalidraw
Virtual whiteboard for hand-drawn diagrams
Free124.9K
PA11Y
accessibility testing tool to find issues with your web pages. It runs HTML CodeSniffer from the command line for programmatic accessibility reporting. It's an accessibility developer tool.  
Alternatives to PA11Y
MarkText
Next generation markdown editor, running on platforms of MacOS Windows and Linux. [![Open-Source Software][OSS Icon]](https://github.com/marktext/marktext) ![Freeware][Freeware Icon]
Open Source57.1K
Penpot
Open-source design and prototyping platform
Open Source49.4K
tldraw
Infinite canvas drawing tool
Free47.6K