Glossary
SharePoint Framework (SPFx)
SPFx is Microsoft's development model for extending modern SharePoint: a TypeScript and React toolchain that produces web parts and extensions running client-side, inside the page, with the signed-in user's own permissions.
It replaced the older add-in and full-trust models. Components built with it look native because they use the same design system and inherit the site theme, rather than rendering inside an embedded container.
The cost people underestimate is upkeep: Microsoft moves the framework. Gulp was retired from SPFx 1.22 in favour of Heft, and domain-isolated web parts were retired outright in April 2026. Every custom solution follows that calendar whether its owner has budget for it or not.