This online service allows you to check MIB (Management Information Base) files for SMI compliance and PIB (Policy Information Base) for SPPI compliance. It uses Muonics MIB Smithy SDK as its back end, allowing you try out MIB Smithy's compiler capabilities without downloading, while working toward good MIB design in the process. The service is free to use, although donations are appreciated. When you're ready for full validation capabilities without the limitations of the online version, consider purchasing a license for MIB Smithy Professional, Standard or SDK
Recommended Reading: 17 Common MIB Design Errors