`dockerfilelint` is a Node‑based command‑line tool that parses Dockerfiles and flags common mistakes, security pitfalls, and deviations from Docker best‑practice guidelines (e.g., missing tags, improper `apt‑get` usage, sudo, invalid syntax). It’s aimed at developers and DevOps engineers who write Docker images and want automated validation either locally, in CI pipelines, or via the provided Docker container/online demo.