Developer Utilities · Free tool
Dockerfile Lint Helper
Scan a Dockerfile for common smells — latest tag, no USER, ADD for URLs, secrets in RUN, missing HEALTHCHECK, and more.
Updated April 2026
7 issues found
- info—No HEALTHCHECK instruction — container orchestrators can't verify readiness.
- error—No non-root USER declared — container will run as root.
- warnL1Avoid 'latest' tag — pin an explicit version for reproducible builds.
- warnL3COPY . before dependency install breaks cache — copy package files first, install, then copy rest.
- warnL4apt-get update in separate RUN — combine with install to avoid cached stale indexes.
- warnL43 separate RUN layers — consider combining with && to reduce image layers.
- warnL5apt-get install should use --no-install-recommends to reduce image size.
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What it does
Linter-grade check for Dockerfile smells before you ship an image.
Runs entirely in your browser — no upload, no account, no watermark. For more tools in this category see the full tools index.
How to use it
- Paste the Dockerfile.
- Read issue list with line numbers.
- Fix and re-check.
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