actionlint

Overview

For maintainers of GitHub Actions workflows, actionlint is a focused static checker that can catch structural and semantic errors before they disrupt automation. It is a strong fit when workflow correctness matters; teams seeking analysis of application code itself will need a different tool.

Key features

Checks cover workflow syntax, including missing and unexpected keys, and the types and properties used in ${{ }} expressions. That makes actionlint useful for spotting mistakes that a basic syntax check can miss. It also validates action inputs and outputs, along with inputs, outputs, and secrets across reusable workflows and workflow calls.

Security checks flag risks such as script injection through untrusted inputs and hard-coded credentials. They add workflow-specific scrutiny, but do not replace security analysis of the rest of a codebase. For scripts in run: steps, integrations with ShellCheck and Pyflakes extend checking beyond the workflow language; both integrations can be disabled when they are not wanted.

Configuration can define self-hosted runner labels, configuration variables, and file-path-based ignore patterns. The project provides Go APIs for embedding its checks in Go programs. Installation choices include prebuilt binaries, Docker, building from source, a CI download script, and package managers, while integrations cover reviewdog, GitHub Problem Matchers, super-linter, pre-commit, editors, and trunk. The browser playground runs through WebAssembly and says it keeps data in the browser, which offers a convenient way to try a workflow without sending it elsewhere.

Pricing

actionlint is free and open source under the MIT license. Its actionlint plan costs nothing and includes the static checker, command-line tool, and browser playground. There is no paid tier to unlock the stated checks, so the trade-off is that this is a focused tool rather than a broader commercial analysis suite.

Platforms

Platforms include Linux, macOS, Windows, self-hosted environments, and the web playground. The documented install routes suit command-line and CI use, while editor and CI integrations let teams fit checks into existing review workflows.

Who it's for

Choose actionlint if you maintain GitHub Actions workflows and want checks for workflow structure, expressions, interfaces, and selected security risks. It is less suitable as a standalone choice for teams whose primary need is linting general-purpose source code or another file format.

Pros and cons

• Pros: Combines syntax, expression, reusable-workflow, and security checks, addressing several classes of workflow mistakes in one focused tool.
• Pros: Multiple installation and integration options support command-line, CI, editor, and browser-playground use.
• Cons: Its scope is GitHub Actions workflows, so it does not serve as a general-purpose code analyzer.
• Cons: ShellCheck and Pyflakes integration is limited to scripts in run: steps, and can be turned off.

Alternatives

For a broader directory of tools in this category, browse Linters.

Pick Biome instead for its open-source toolchain for web projects. Cppcheck offers a free-to-download static analysis core and a Project plan; choose it when that tool is the better fit for your analysis needs. Hadolint is an open-source Dockerfile linter, while JSHint is a publicly available option with no paid plans stated.

PMD is a downloadable static code analyzer under a BSD-style license. Ruff is an open-source, permissively licensed developer tool for the Python ecosystem. For shell-script analysis across web, terminal, and editor use, consider ShellCheck. SwiftLint is an MIT-licensed Swift linting tool.

Verdict

For developers responsible for GitHub Actions, actionlint is a clear choice when the priority is catching workflow-specific errors without adding a software license cost. Its focused checks and flexible integration options are its main strengths. Look elsewhere if you need a linter for application code or a language outside workflow files.