Templates
Start from a diagram that is already right
Every template here is a real model rather than a picture: the relationships are legal, the multiplicities are filled in, and the element that most first drafts get wrong is already drawn correctly. Rename the boxes and the structure holds.
Free to use, in every notation Archyno speaks. No account needed to look.
Class diagram
UML 2.5.1A ready-made UML class diagram: customer, order, order line, product and a payment method interface with two realizations. Rename the classes and the structure is already right.
Sequence diagram
UML 2.5.1A ready-made UML sequence diagram: a request that authenticates, branches on the result and replies. Activations, reply arrows and an alt fragment are all in place.
Use case diagram
UML 2.5.1A ready-made UML use case diagram: customer and administrator actors, a system boundary, and four use cases wired with include and extend. Rename the ovals and the scope is stated.
ER diagram
ER - crow's footA ready-made entity-relationship diagram: customer, order, order line, product, category and the junction entity between them, with keys and cardinality already correct.
Entity-relationship diagram
ArchiMate layered view
ArchiMate 4A ready-made ArchiMate layered view: a business process served by an application service, itself served by a technology service, in the spec's own layer colours.
Layered view
Cloud architecture
UML 2.5.1A ready-made cloud architecture diagram: browser, CDN, load balancer, application runtime, managed database and cache, inside a region boundary, with protocols and ports on every path.
Deployment diagram