CSS Scan - Instantly check or copy computed CSS from any element for only ~95$
MIT License - A license from the Massachusetts Institute of Technology.
CodePen - A front end web development playground.
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CodeOcean - Code Ocean is a research collaboration platform. Create, collaborate on, share, execute, and publish computational code and data from anywhere, with anyone.
AGPL - GNU Affero General Public License. Strong license for applications designed to guarentee user freedoms to access, modify, and redistribute server-side code.