Metasyn vs Mockaroo

Metasyn generates synthetic tabular data to help make sensitive datasets more accessible, reproducible, and reusable. Users fit a MetaFrame to a dataframe, save the model and settings as auditable JSON, then generate new rows. It handles varied data types, missing values, categories, unique key columns, and structured strings such as postcodes or identifiers. Metasyn supports pandas and Polars dataframes and uses Faker for localized names, emails, phone numbers, and other data. By default, its model excludes multivariate information to reduce disclosure risks. A disclosure-control plugin is available, but synthetic output still needs human review and is not guaranteed to be free of sensitive information. The plugin system allows users and organizations to add extensions. Generated dataframes can be exported to CSV, Parquet, Excel, and other formats. The free, MIT-licensed Python package is self-hosted and can be installed with pip from PyPI or directly from GitHub. The project also points users to versioned Docker containers and a command-line interface. Its intended users include public organizations, research groups, and individual researchers with sensitive datasets.

Mockaroo is a web-based synthetic data generator for developers and testers who need realistic test records or a mock back end while building a user interface. It offers more than 100 built-in data types; users can also upload reference data or define types with the formula API. The Generate API produces JSON, CSV, tab-separated or custom-delimited text, SQL, and XML. Mock APIs can connect request parameters to schemas and return dynamic or static data, or simulate errors. Both APIs require an API key, sent as a query parameter or an X-API-Key header. Free includes 1,000 rows per file and 200 API requests per day. Silver is $60 a year and allows 100,000 rows per file and 1 million API records per day; Gold is $500 a year and allows 10 million rows per file and 10 million API records per day. Synchronous API responses are limited to 5,000 records on every plan; background generation requires a paid plan. Enterprise is $7,500 a year, with unlimited data and users and Docker deployment in a private cloud or datacenter.