The Web IDE uses the [Monaco editor](https://microsoft.github.io/monaco-editor/) which uses the [Monarch library](https://microsoft.github.io/monaco-editor/monarch.html) for syntax highlighting.
The Web IDE currently supports all languages defined in the [monaco-languages](https://github.com/microsoft/monaco-languages/tree/master/src) repository.
You'll find a list of [unsupported languages in this epic](https://gitlab.com/groups/gitlab-org/-/epics/1474), which is the right place to add more if needed.
Should you be willing to help us and add support to GitLab for any missing languages, here are the steps to do so:
1. Create a new issue and add it to [this epic](https://gitlab.com/groups/gitlab-org/-/epics/1474), if it doesn't already exist.
2. Create a new file in this folder called `{languageName}.js`, where `{languageName}` is the name of the language you want to add support for.