Act vs RegExr

act is an open-source command-line tool that runs GitHub Actions workflows locally using Docker containers. It reads workflow files from .github/workflows/ and executes them with environment variables and filesystem configurations matching GitHub's hosted runners. The tool enables fast local feedback on workflow changes without requiring commits and pushes to a remote repository.

RegExr is Online tool for learning, building, and testing regular expressions with syntax highlighting and a community pattern library.. It is available under a free model. This tool falls under the developer utilities category.