What is Maester?
Maester is an open source PowerShell-based test automation framework designed to help you monitor and maintain the security configuration of your Microsoft 365 environment. It runs as a PowerShell module, and the tests ship inside it, so there is nothing else to download. The Maester team adds new tests over time, and updating the module updates the tests.
Maester needs PowerShell 7.4 or later on Windows, Linux or macOS and installs with Install-Module. You connect with Connect-Maester and run Invoke-Maester. You can tailor it with your own tests, per-tenant configuration and test parameters, and connect to national cloud environments such as China, USGov and USGovDOD.
Results export to CSV, Excel, HTML, JSON or Markdown, notifications go to email, Teams or Slack, and Maester can run in a GitHub, Azure DevOps or GitLab pipeline. The README notes that the preview build is now Maester 3.0, which has breaking changes, including the PowerShell 7.4 requirement.
Key capabilities
- Automated tests Checks of Microsoft 365 security configuration that ship inside the module.
- Custom tests Your own tests, per-tenant configuration and test parameters.
- Exports CSV, Excel, HTML, JSON or Markdown results.
- Notifications Email, Teams or Slack.
- Pipelines GitHub, Azure DevOps or GitLab workflows.
- National clouds Global, China, USGov and USGovDOD environments.
Where Maester fits
Maester fits into recurring tenant security reviews and automated configuration checks maintained by system administrators and IT teams. Its report exports support reviewing findings outside the PowerShell session, while pipeline execution allows checks to become part of an existing operational workflow.
Before deployment, teams should select the release or preview channel deliberately and verify the corresponding PowerShell and custom-test requirements. The preview requires PowerShell 7.4 or later. The project also warns against ExchangeOnlineManagement 3.9.2 because of connection errors, and existing GitHub workflows using the old action need migration to the separate action repository.
Install
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