The main tool is a configuration parser. Instead of using Notepad or other text editors, it's purpose-built for networking.
There's also an access-list evalulator to test packets against access-lists.
Just start typing and it goes right to work.
JavaScript that's run right in your browser—IE 11+, Firefox, Chrome, any common OS on any device with a large-enough screen—parses it and gives its opinion.
Your configuration workspace is saved to your device—not to a cloud service. You stay in control of your data and your passwords.
It supports configurations from Cisco IOS/IOS XE devices, for common features, especially those used in enterprise/corporate networks.
Tell me what you're looking for. Or, if you're willing to write code, go to the repository and submit a pull request.
Your browser's privacy settings or the use of private browsing mode may prevent saving of configurations. To save configurations, disable these privacy settings or don't use private browsing.