The web-based editor introduces a new, lightweight editing experience that runs entirely in your browser. With the web editor, you can navigate files and source code repositories from GitHub, and make and commit code changes. You can open any repository, fork, or pull request in the editor.
The web-based editor is available to everyone for free on GitHub.com.
Source: Web-based editor - GitHub Docs
This is much better than Codespaces for simple tasks.