GitHub Actions Matrix Preview
Expand GitHub Actions matrix axes, include rules, and exclude rules into a concrete job preview.
Also useful for: github actions matrix github matrix preview actions matrix generator workflow matrix checker GitHub Actions Matrix Preview
GitHub Actions Matrix Preview
Runs in your browser. Inputs are not uploaded.GitHub Actions Matrix Preview Example Run
Expand matrix axes before a workflow creates too many jobs.
Sample inputs
{"os":["ubuntu-latest","macos-latest"],"node":[18,20],"exclude":[{"os":"macos-latest","node":18}],"include":[{"os":"windows-latest","node":20,"experimental":true}]}
Generated result
Summary: 4 matrix jobs previewed across 2 axes.
Stats
- Jobs: 4
- Axes: 2
Issues
- No issues found.
Output
1. {"os":"ubuntu-latest","node":18}
2. {"os":"ubuntu-latest","node":20}
3. {"os":"macos-latest","node":20}
4. {"os":"windows-latest","node":20,"experimental":true} What the GitHub Actions Matrix Preview Checks
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Matrix axes
Array-valued keys are expanded into concrete job combinations.
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Exclude rules
Combinations matching every key in an exclude object are removed from the preview.
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Include rules
Included combinations are appended so special-case jobs are visible.
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Simple YAML fallback
Basic lines such as os: [ubuntu-latest, macos-latest] can be parsed when JSON is not pasted.
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Large matrix warning
More than 128 jobs triggers a truncation warning so runaway matrices are obvious.
GitHub Actions Matrix Preview Questions
- Q: Does the GitHub Actions matrix preview upload my matrix config? A: No. Inputs are processed in your browser, and pasted content is not sent to analytics or a server.
- Q: What should I paste into the GitHub Actions matrix preview? A: Paste matrix JSON, a strategy.matrix object, or simple YAML array lines.
- Q: What can I copy or download? A: You can copy the expanded job list.
- Q: What does the GitHub Actions matrix preview not verify? A: It does not evaluate expressions, fromJSON outputs at runtime, reusable workflows, or GitHub-hosted runner availability.
Related Tools
Updates
- v1.0.0 New 2026-05-17: Initial matrix expansion with include, exclude, and large-job warnings added.