cddlparser provides a spec‑authoring‑focused parser for the Concise Data Definition Language (CDDL) in both Python and JavaScript/TypeScript. It builds a full‑fidelity AST that preserves whitespace and comments, validates CDDL syntax against the RFC 8610 grammar, and enables round‑trip serialization (including custom markup) for tools like Bikeshed and ReSpec. The library is aimed at developers writing or processing CDDL specifications who need precise, reversible parsing rather than compact data‑validation utilities.