Greenmask

Greenmask is an open-source utility for dumping, masking, subsetting, generating synthetic data and restoring databases. It best suits teams working with PostgreSQL who need an on-premises tool they can automate in CI/CD. Its broad transformation and storage options are compelling, but MySQL remains in beta and Windows is not supported by its install script.

Overview

Greenmask focuses on logical database workflows: it uses PostgreSQL’s own pg_dump and pg_restore utilities for schema dumps and restoration, and those dumps can also be restored with pg_restore. That familiar foundation makes it a practical fit for PostgreSQL teams already using these tools. PostgreSQL 11 and later are supported; MySQL support is still in progress and beta, so it is not a dependable choice for production MySQL workflows.

Greenmask describes its masking as stateless and performed in flight. In its normal workflow, unmasked datasets do not need to be stored persistently, which can help teams reduce exposure while preparing development or test data. The utility is designed for CI/CD automation, rather than just occasional manual exports.

Key features

Masking and synthetic data

Static masking can use deterministic or random transformers, dynamic parameters and conditional rules. Inheritance across partitions and foreign-key references helps keep transformations consistent across related data. Teams can also build custom transformers that communicate through standard input and output, with predefined templates as a starting point. This flexibility is useful for tailored anonymization, though it means the masking approach depends on configuring transformations for the data at hand.

Synthetic data generation adds another way to prepare non-production datasets. Greenmask also supports subsetting while preserving referential integrity, including cyclic and polymorphic references. That makes smaller development databases more useful than extracts that break relationships, particularly for teams working with complex schemas.

Storage and restoration

Dumps can go to local directories, S3-compatible storage, Azure Blob Storage or SSH/SFTP. These choices suit teams with different storage setups without changing Greenmask’s PostgreSQL-based dump and restore workflow.

Pricing

Greenmask — free. The free, open-source utility includes PostgreSQL support, with MySQL support in progress. There is no paid tier described; the key trade-off is database coverage rather than a stated usage quota. PostgreSQL teams can use the core utility at no cost, while teams needing established MySQL support should look elsewhere.

Platforms

Greenmask is self-hosted and supports Linux and macOS. Its installation script does not support Windows yet, which rules it out for teams that require a Windows installation path. The deployment model suits organizations that want to run database preparation within their own environment.

Who it's for

Greenmask is a strong fit for PostgreSQL teams that need repeatable anonymized or synthetic datasets, smaller referentially sound development copies, and automated restoration in CI/CD. It is less suitable for MySQL-first teams today, or for users who need a supported Windows installation.

Pros and cons

• Pros: Free and open source, with PostgreSQL support from version 11 onward.
• Pros: Subsetting preserves complex relationships, including cyclic and polymorphic references.
• Pros: In-flight transformations and a stateless design avoid persistent storage of unmasked datasets in the normal workflow.
• Pros: Multiple storage backends, custom transformers and CI/CD integration support varied automated workflows.
• Cons: MySQL support is beta and in progress, limiting its suitability for established MySQL workloads.
• Cons: The installation script supports Linux and macOS, not Windows.

Alternatives

For a broader comparison, see Data Masking Software.

• MySQL is worth considering when you need a free community edition with SQL and NoSQL applications, replication and high-availability components, or Windows support.
• ARX Data Anonymization Tool is another free, open-source option, with Linux, macOS, Windows and API platforms.
• DataVeil may fit Windows-based workflows; its free Community License covers databases up to 10GB and includes dataset and user SQL masks.
• Jailer is a free database tool for Linux, macOS and Windows.
• MOSTLY AI offers a free plan and supports API, Linux, self-hosted and web platforms.
• PostgreSQL Anonymizer is a free PostgreSQL-focused alternative, with commercial support available separately.
• Data Mask Studio is a free, open-source Windows desktop app.
• Oracle Cloud Infrastructure Secret Management is another free option, available through API and web platforms.

Verdict

Choose Greenmask if your team runs PostgreSQL 11 or later and wants free, self-hosted masking, integrity-preserving subsets and automated restore workflows. Its strongest case is the combination of flexible transformations and in-flight handling; its clearest reasons to look elsewhere are beta MySQL support and the lack of a Windows installation path.