> For the complete documentation index, see [llms.txt](https://build-it-the-right-way.gitbook.io/home/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://build-it-the-right-way.gitbook.io/home/design-patterns.md).

# Design Patterns

- [Pattern Library Overview](https://build-it-the-right-way.gitbook.io/home/design-patterns/servicenow-architecture-pattern-library.md): The ServiceNow Architecture Pattern Library is a curated collection of proven design patterns tailored for building scalable, secure, and maintainable solutions on the ServiceNow platform.
- [Pattern 01 · Scoped Application Boundary](https://build-it-the-right-way.gitbook.io/home/design-patterns/pattern-01-scoped-application-boundary.md): The pattern for drawing a clean boundary around a unit of functionality. Inputs, outputs, ownership, lifecycle, and ACL model all defined at the boundary.
- [Pattern 02 · Event-Driven Integration](https://build-it-the-right-way.gitbook.io/home/design-patterns/pattern-02-event-driven-integration.md): The pattern for integrating ServiceNow with external systems through events rather than synchronous calls. Loose coupling, replay, and observability built in.
- [Pattern 03 · ACL by Design](https://build-it-the-right-way.gitbook.io/home/design-patterns/pattern-03-acl-by-design.md): ACLs designed alongside the data model, not added later. Role-driven, scope-aware, and reviewed at Gate 01.
- [Pattern 04 · Reusable Utility Layer](https://build-it-the-right-way.gitbook.io/home/design-patterns/pattern-04-reusable-utility-layer.md): Build once, reuse everywhere. The pattern for a shared utility layer that serves multiple Solution Units without becoming a dumping ground.
- [Pattern 05 · Idempotent Inbound API](https://build-it-the-right-way.gitbook.io/home/design-patterns/pattern-05-idempotent-inbound-api.md): Inbound APIs that can be safely retried. Idempotency keys, deduplication, and the audit trail that proves an operation only happened once.