Custom functions enable reusable data transformation logic across your templates, blueprints, and workflows. They extend JSONata's built-in capabilities, allowing you to encapsulate complex transformation logic, business rules, and data processing into named functions that can be called from anywhere in your templates, blueprints, or workflows.

Functions are based on JSONata - a lightweight query and transformation language for JSON data. Signstack adds semantic versioning (major.minor.patch) and lifecycle management (Draft, Active, Deprecated) on top, allowing your functions to evolve over time while maintaining backward compatibility.

Each function is identified by a unique key and can accept typed parameters and return typed values based on your schemas.