https://github.com/nrc/rustw (there are some screenshots in the README and a link to a demo (although it is very slow and lacks some functionality)).

Rustw is an experiment I’ve been working on recently, it is still very early days, but I’d love to get some early feedback. It is a frontend for the Rust compiler (or Cargo) and is primarily designed to be a better way to present errors to the user. It runs cargo build or whatever build command you specify, but instead of displaying the results in the console, it displays them in the browser. This is prettier, but also more usable since you can control the level of detail displayed (e.g., hiding notes or source snippets), jump to a source view, easily make edits to the code, or show explanations about error codes, etc. To rebuild, just hit F5.

In the future, I would like to leverage the graphical interface to show better information about borrows, interact with macro expansion, etc. I’d like rustw to be an easy way to use multiple toolchains, effectively being a UI for multirust/rustup.rs. I’d also like to use this as a platform for code exploration - implementing some of the features from DXR such as ‘jump to definition’, ‘find uses’, and ‘identifier search’.

As I said, it is very rough at the moment, but please have a play around and let me know what you think. If anyone is interested on hacking on rustw, let me know!