GitHub Actions Matrix Builder

A matrix strategy lets you run a job across multiple configurations simultaneously. Instead of writing separate jobs for each OS or language version, you declare a matrix and GitHub Actions spawns parallel jobs for each combination — e.g., 3 OS × 3 Node versions = 9 parallel jobs.

With fail-fast enabled (default), GitHub Actions cancels all in-progress jobs in the matrix as soon as any one job fails. Disabling it (fail-fast: false) lets all combinations run to completion, which is useful for understanding the full scope of a failure across environments.

Use max-parallel to cap how many jobs run simultaneously. This is useful when you have limited self-hosted runners, want to avoid exhausting rate-limited external services, or need to control costs on pay-per-minute billing.

Yes — the generated YAML includes a sensible steps template for your chosen language. Edit the steps section to add caching, linting, test reporting, deployment steps, or any other custom logic. The matrix variables (matrix.os, matrix.node-version, etc.) are available in all steps.

After generating the base YAML, add an include or exclude block under strategy.matrix. For example, exclude: [{os: windows-latest, node-version: '18'}] prevents that specific combination from running. Include lets you add extra variables to specific combinations.

GitHub Actions supports up to 256 jobs per matrix. Beyond that, you'll need to split into multiple workflows or use dynamic matrix generation via fromJSON. For most projects, keeping the matrix under 20 combinations is recommended for practical CI times.