act vs CodeNav: What are the differences?
Developers describe act as "Run your GitHub Actions locally". Rather than having to commit/push every time you want test out the changes you are making to your .github/workflows/ files (or for any changes to embedded GitHub actions), you can use this tool to run the actions locally. The environment variables and filesystem are all configured to match what GitHub provides. On the other hand, CodeNav is detailed as "A browser extension that improves code navigation on Github". CodeNav is a Chrome extension and Firefox addon that makes navigating code on Github easier and more intuitive. It borrows features from popular IDEs for more seamless movement around code. Hover over a variable to highlight other references and visualize them on your scrollbar. Click a variable or object to search for other instances in the same project.
act and CodeNav can be categorized as "Tools for GitHub" tools.
CodeNav is an open source tool with 126 GitHub stars and 19 GitHub forks. Here's a link to CodeNav's open source repository on GitHub.