# Hadolint

> GPL-3.0 AST Dockerfile linter + ShellCheck on RUN

**Category:** DevOps  
**Pricing:** open-source  
**URL:** https://hadolint.github.io/hadolint/  
**GitHub:** https://github.com/hadolint/hadolint  
**Added:** 2026-09-14

---

## The Hook

Hadolint is Dockerfile best-practice as an AST when `docker build` green still ships a 1.4 GB image and a broken RUN.

## What's Good

GPL-3.0. hadolint/hadolint. Parses Dockerfiles into an AST, applies DL#### rules, and runs ShellCheck on `RUN` shell. Online try-out at hadolint.github.io/hadolint; source github.com/hadolint/hadolint.

## The Catch

GPL-3.0 copyleft — same class as ShellCheck; not MIT. Vs Docker (the engine), dive (*layer/size forensics*), and lazydocker (Docker/Compose *TUI*): Hadolint is the *Dockerfile linter*, not a runtime, not layer diffs, not a container dashboard.

## Verdict

GPL-3.0 Dockerfile linter. Free forever; lint the recipe, dive the layers, lazydocker the running boxes.