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Dockerfile Linter

Lint Dockerfiles against 20+ valid instructions (FROM, RUN, CMD, COPY, ENTRYPOINT, HEALTHCHECK, SHELL). Detects unknown instructions and missing FROM declaration. Code never leaves your device — formatting and validation run locally in your browser.

100% Local Browser Native

How to Use the Dockerfile Linter

1. Paste source for Dockerfile Linter

Paste source for Dockerfile Linter into the input area. Nothing runs until you trigger it.

2. Lint

Lint and read each issue with its line.

3. Fix and relint

Fix issues and re-lint.

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Frequently Asked Questions

What gets flagged?

Missing tags (:latest), root users, cache-busting order, and secret leaks.

Base image pinning?

Digests beat tags — immutable references only, never floating majors.

Multistage builds?

Recognized and scored — builder patterns get proper treatment.

Is my input uploaded anywhere when using Dockerfile Linter?

No — linting runs locally in your browser, free with no signup.

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Last updated October 2026