abaplint
What it is
An open-source, system-independent ABAP linter and parser. It runs from CI or an editor against your source files (no SAP system needed) to enforce naming, style and many cleanliness rules early.
Why it matters for Clean Core
It moves quality left: catch issues in the pull request, before they reach the system ATC run. RAP Dojo's in-app linter is built on abaplint, and it's the engine behind offline cloud-readiness pre-checks.
Common pitfall
Expecting abaplint to know your system's release states. It's a parser/style gate, not a substitute for ATC's released-API check — semantic Clean Core findings (is this API released on MY system?) still need ATC.