Plugin architecture (microkernel)

A small core with a defined extension interface, and features added as plugins that can be built, enabled or removed separately.

Editors, browsers, ERPs and many SaaS products use it so customers or partners can add features without forking the product. The core owns data, security and the plugin contract; plugins get only the hooks they are given. The hard part is the contract: once outside plugins depend on it, every change needs versioning and a deprecation path.

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Related terms

Hexagonal architecture (ports and adapters): Business logic in the middle defines interfaces (ports); databases, APIs and user interfaces plug in from outside as adapters.
Modular monolith: One deployable application split inside into modules with clear boundaries, each owning its data and using the others only through defined interfaces.
Multi-tenancy (multi-tenant SaaS): One application and one deploy serving many client companies, with each client’s data kept apart.

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