Run compilers interactively from your web browser and interact with the assembly
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![Compiler Explorer](views/resources/site-logo.svg)

# Compiler Explorer

**Compiler Explorer** is an interactive compiler exploration website. Edit code in C, C++, C#, F#, Rust, Go, D, Haskell,
Swift, Pascal, [ispc](https://ispc.github.io/), Python, Java or in any of the other
[30+ supported languages](https://godbolt.org/api/languages), and see how that code looks after being compiled in real
time. Multiple compilers are supported for each language, many different tools and visualisations are available, and the
UI layout is configurable (thanks to [GoldenLayout](https://www.golden-layout.com/)).

Try out at [godbolt.org](https://godbolt.org), or [run your own local instance](#running-a-local-instance).

**Compiler Explorer** follows a [Code of Conduct](CODE_OF_CONDUCT.md) which aims to foster an open and welcoming
environment.

**Compiler Explorer** was started in 2012 to show how C++ constructs translated to assembly code. It started out as a
`tmux` session with `vi` running in one pane and `watch gcc -S foo.cc -o -` running in the other.

Since then, it has become a public website serving around
[3,000,000 compilations per week](https://www.stathat.com/cards/Tk5csAWI0O7x).

You can financially support [this project on Patreon](https://patreon.com/mattgodbolt),
[GitHub](https://github.com/sponsors/mattgodbolt/),
[Paypal](https://www.paypal.com/cgi-bin/webscr?cmd=_donations&business=KQWQZ7GPY2GZ6&item_name=Compiler+Explorer+development&currency_code=USD&source=url),
or by buying cool gear on the [Compiler Explorer store](https://shop.spreadshirt.com/compiler-explorer/).

## Using Compiler Explorer

### FAQ

There is now a FAQ section [in the repository wiki](https://github.com/compiler-explorer/compiler-explorer/wiki/FAQ). If
your question is not present, please contact us as described below, so we can help you. If you find that the FAQ is
lacking some important point, please free to contribute to it and/or ask us to clarify it.

### Videos

There are a number of videos that showcase some features of Compiler Explorer:

- [Presentation for CppCon 2019 about the project](https://www.youtube.com/watch?v=kIoZDUd5DKw)
- [Older 2 part series of videos](https://www.youtube.com/watch?v=4_HL3PH4wDg) which go into a bit more detail into the
  more obscure features.
- [Just Enough Assembly for Compiler Explorer](https://youtu.be/QLolzolunJ4): Practical introduction to Assembly with a
  focus on usage on Compiler Explorer, from CppCon 2021.
- [Playlist: Compiler Explorer](https://www.youtube.com/playlist?list=PL2HVqYf7If8dNYVN6ayjB06FPyhHCcnhG): A collection
  of videos discussing Compiler Explorer; using it, installing it, what it's for, etc.

A [Road map](docs/Roadmap.md) is available which gives a little insight into the future plans for **Compiler Explorer**.

## Developing

**Compiler Explorer** is written in [Node.js](https://nodejs.org/).

Assuming you have a compatible version of `node` installed, on Linux simply running `make` ought to get you up and
running with an Explorer running on port 10240 on your local machine:
[http://localhost:10240/](http://localhost:10240/). If this doesn't work for you, please contact us, as we consider it
important you can quickly and easily get running. Currently, **Compiler Explorer** requires
[`node` 16 _(LTS version)_](CONTRIBUTING.md#node-version) installed, either on the path or at `NODE_DIR` (an environment
variable or `make` parameter).

Running with `make EXTRA_ARGS='--language LANG'` will allow you to load `LANG` exclusively, where `LANG` is one for the
language ids/aliases defined in `lib/languages.ts`. For example, to only run **Compiler Explorer** with C++ support,
you'd run `make EXTRA_ARGS='--language c++'`. The `Makefile` will automatically install all the third party libraries
needed to run; using `npm` to install server-side and client side components.

For development, we suggest using `make dev` to enable some useful features, such as automatic reloading on file changes
and shorter startup times.

You can also use `npm run dev` to run if `make dev` doesn't work on your machine.

Some languages need extra tools to demangle them, e.g. `rust`, `d`, or `haskell`. Such tools are kept separately in the
[tools repo](https://github.com/compiler-explorer/compiler-explorer-tools).

Configuring compiler explorer is achieved via configuration files in the `etc/config` directory. Values are `key=value`.
Options in a `{type}.local.properties` file (where `{type}` is `c++` or similar) override anything in the
`{type}.defaults.properties` file. There is a `.gitignore` file to ignore `*.local.*` files, so these won't be checked
into git, and you won't find yourself fighting with updated versions when you `git pull`. For more information see
[Adding a Compiler](docs/AddingACompiler.md).

Check [CONTRIBUTING.md](./CONTRIBUTING.md) for detailed information about how you can contribute to **Compiler
Explorer**, and the [docs](./docs) folder for specific details regarding various things you might want to do, such as
how to add new compilers or languages to the site.

### Running a local instance

If you want to point it at your own GCC or similar binaries, either edit the `etc/config/LANG.defaults.properties` or
else make a new one with the name `LANG.local.properties`, substituting `LANG` as needed. `*.local.properties` files
have the highest priority when loading properties.

When running in a corporate setting the URL shortening service can be replaced by an internal one if the default storage
driver isn't appropriate for your environment. To do this, add a new module in `lib/shortener/myservice.js` and set the
`urlShortenService` variable in configuration. This module should export a single function, see the
[tinyurl module](lib/shortener/tinyurl.js) for an example.

### RESTful API

There's a simple restful API that can be used to do compiles to asm and to list compilers.

You can find the API documentation [here](docs/API.md).

## Contact us

We run a [Compiler Explorer Discord](https://discord.gg/B5WacA7), which is a place to discuss using or developing
Compiler Explorer. We also have a presence on the [cpplang](https://cppalliance.org/slack/) Slack channel
`#compiler_explorer` and we have
[a public mailing list](https://groups.google.com/forum/#!forum/compiler-explorer-discussion).

There's a development channel on the discord, and also a
[development mailing list](https://groups.google.com/forum/#!forum/compiler-explorer-development).

Feel free to raise an issue on [github](https://github.com/compiler-explorer/compiler-explorer/issues) or
[email Matt directly](mailto:matt@godbolt.org) for more help.

## Credits

**Compiler Explorer** is maintained by the awesome people listed in the [AUTHORS](AUTHORS.md) file.

We would like to thank the contributors listed in the [CONTRIBUTORS](CONTRIBUTORS.md) file, who have helped shape
**Compiler Explorer**.

We would also like to specially thank these people for their contributions to **Compiler Explorer**:

- [Gabriel Devillers](https://github.com/voxelf) (_while working for [Kalray](http://www.kalrayinc.com/)_)
- [Johan Engelen](https://github.com/JohanEngelen)
- [Joshua Sheard](https://github.com/jsheard)
- [Andrew Pardoe](https://github.com/AndrewPardoe)

A number of [amazing sponsors](https://godbolt.org/#sponsors), both individuals and companies, have helped fund and
promote Compiler Explorer.
