Support
One developer, one address, and answers to the questions that come up most.
Contact:
One person reads it. Expect a reply within two business days. The button opens a draft in your own mail app; nothing is sent from this page.
Common questions
A crate will not compile
Crabrix compiles to wasm32-wasip1 with a bundled compiler that has no
linker for native code. Crates that need C code, procedural macros, or a build
script generally cannot build on device. Checks flag known incompatibilities
before compilation. Some compiler backend gaps can still cause build errors.
The Packages screen says which of your dependencies
are verified, expected to work, or blocked, and why.
A build is slow
The first compile of a project is genuinely doing the work — a real compiler, running in a WebAssembly interpreter, on a phone. Identical repeat runs come from a local artifact cache and are much faster. Large dependency trees take longer on first fetch; after that they rebuild offline.
Can I practise whenever I want?
Yes. Lessons, Quick Practice, Term Train, and Code Recall have no Health or Energy limit. Your progress and achievements stay on your device.
Where are the Rust Examples?
Open Learn → Code Examples. On a new installation, confirm the displayed size to download the separate signed Examples pack. Opening an example makes an editable copy in My Projects; updating or deleting the course does not remove your copy.
Where are my projects stored?
In the app's own container on your device. Save a project to Files or iCloud Drive from the Projects screen if you want a copy you control, or use Archive & Share for a plain ZIP. Deleting the app deletes everything that was only inside it.
Does it work offline?
The bundled compiler, installed courses, and local projects work offline. A course can be read without network access after installation; its crate exercises also need their dependencies prepared. Pin for Offline keeps exact verified crate archives durable after cache eviction. First-time course and package downloads, and GitHub imports need a connection.
A course download was interrupted
Open Learn and check that course's row. A partial download never becomes the active course; any previous installed version remains readable. Tap Resume after reconnecting. If the course says the app is incompatible, install a compatible app version rather than downloading a compiler or plugin from a course. Your separate projects and learning progress are not part of the course archive.
Do I need an account?
No. There is no sign-up, no password, and no email address to give. Crabrix has no Crabrix account or online profile. Your rating stays on your device unless you choose to share it through Apple's optional Game Center switch in Profile.
Bugs and feature requests
The shortest route is inside the app: Settings → Help & problems → Report a problem. Pick the area, say what happened and what you expected, and it opens a mail draft with the version, iOS, device model and toolchain already filled in. For a course issue, include the course name and installed version if you choose; source code is not attached by default. Nothing is sent by the app — you read the draft and send it yourself, and you can turn the attached details off before you do.
Otherwise use the form below, or open an issue on GitHub. For a build problem it helps enormously to include the Rust code and the compiler output from the Problems tab.
Refunds
Purchases are handled by Apple, so refunds go through Apple rather than through me: reportaproblem.apple.com. If something about the app is broken, write to me too — I would rather fix it.