Press Run ▸ or Ctrl+Enter.
Write a contract; watch the compiler check it. Tokens, LLVM IR, contracts and diagnostics side by side.
Run and Format compile and execute on our servers in a sandboxed container. The Diagnostics and LLVM IR tabs also have an in-browser WASM preview for pure programs.
Local backup in your browser — no account needed.
Why learn with XIOM?
A language built to catch mistakes at compile time and fail loudly at runtime — with a playground that keeps learners moving.
Fails loudly, never silently
Contract guards and overflow checks abort with a structured diagnostic instead of corrupting state.
Compiles to native code
Your program builds to a native binary. The first run compiles it (a few seconds); running the same code again is instant.
Learn by doing
Interactive lessons from zero to confident, with expected-output checks: every solution is type-checked and executed in CI.
Free forever
No payments. No ads. No account required. Sign in only to sync your progress. Open source, always free.
Working with AI agents? See --ai diagnostics and the MCP server.
Support XIOM
XIOM is funded through Open Collective, hosted by Open Source Europe. Sponsorships and donations support the compiler, the standard library, the registry and the tooling.
Tiers and amounts are read live from the collective; the contribution itself happens on Open Collective.