The application describes its needs
Content, configuration and interfaces described with AUP (Agentic UI Protocol) form a definition the runtime can read. People and agents work with an explicit application structure.
AUPBlocklet: from reusable components to declarative applications
Since the 2017 whitepaper stage, Blocklet has carried one idea: make software reusable and composable. Its form has evolved—from a component concept, through installable applications and services on Blocklet Server, to application definitions operated by ARC.
How Blocklet evolved
Each stage expanded what a Blocklet could contain and how it could be reused. ARC changes the implementation model while retaining the name and the idea of composition.
2017 · Whitepaper concept
Reusable components
The original concept covered reusable components in both on-chain and off-chain forms. It was an architectural idea for assembling applications, before the later Blocklet Server implementation took shape.
Architecture retrospective · 20232020 · ABT Node / early Blocklet Server
Installable web applications
Early implementations focused on frontend web applications paired with standard backend services. The platform was then called ABT Node; it became Blocklet Server in 2022. Its installation and management experience made applications easier to run and combine.
Installation and management · 2020Blocklet Server · Services
A Blocklet can bring its backend
Standard composable Blocklet services brought frontend and backend together; individual Blocklets could also carry backend logic. The architecture retrospective records the addition of serverless services in 2022, as applications and reusable services became clearer parts of the platform.
Services in the architecture retrospective · 20232022–2024 · Richer composition
Finished applications become components
Blocklet Server 1.8.0 documented multi-level nesting and repeated components in 2022. By 2024, the website anatomy article showed Pages Kit, Discuss Kit, Media Kit and other finished Blocklets working together as one site.
How the website was assembled · 20242024-11 · Production-ready Docker support
Docker expands the runtime options
Blocklet Server 1.16.33 announced production-ready Docker support: custom Dockerfiles, hooks running inside containers, and improved CPU and memory controls. This expanded runtime choices and isolation; actual protection still depends on container and host configuration.
Read the 1.16.33 release2026 · ARC application model
From a software package to an application definition
The name remains, but the model changes substantially: a Blocklet declares content, resources and interactions while ARC provides the runtime capabilities. Composition increasingly concerns declared resources and interfaces, rather than bundling another application server into every package.
Read the transition
What changes in ARC
In the Blocklet Server model, an application can bring its own backend and runtime dependencies. In ARC, a Blocklet centers on declared content, resources and interfaces. ARC supplies common capabilities; specialized integrations are exposed through explicitly mounted AFS Providers.
Capabilities come through resources
AFS gives authorized data and services a common path-based interface. A Provider supplies the integration; declaring a path does not grant permission by itself.
AFSThis website is a Blocklet
The ArcBlock website runs as an ARC Blocklet, with content collections and AUP page definitions. Its repository is a concrete example of the newer model.
View site sourceChoose the documentation for your runtime
Blocklet Server: packages and composition
The package specification, service composition and Docker guides document the Blocklet Server model. They remain useful for applications built on that platform.
Package specificationARC: application definitions and resources
Read the transition to ARC, then explore AFS and AUP. Keeping the Blocklet name does not imply that a Blocklet Server package runs unchanged in ARC.
From Blocklet Server to ARC