# ProcBlocks Overview ProcBlocks (Processor Blocks) is a **declarative YAML-based Markup Language** for defining image-processing pipelines as a stack of processor blocks—much like HTML describes webpage structure. Instead of writing custom code for each edit, you author **Block Sequences**. **Key concepts:** - **YAML block syntax**: Each top-level list item defines an `assign`, `processor`, or `job` block. - **Inputs & Outputs**: Blocks read from and write to a virtual filesystem. - **Virtual Filesystem**: The filesystem mounts server memory, account stores, local and network shares, as simple paths. - **Processors**: Files are processed through parameterized processor blocks and written back to the filesystem. - **Advanced Parsing**: Use inline methods (`{width:source}`) and expressions (`[[10+5]]`) to access metadata, compute values, or branch logic. - **Nested Job Definitions**: Embed entire job definitions inside one another for modular workflows. - **User Input**: Define custom UI elements to gather parameters at runtime. **Why ProcBlocks?** - **Readability**: Declarative YAML + named blocks makes pipelines easy to scan and maintain. - **Extensibility**: Add or nest custom processors without rewriting core logic. - **Consistency**: Built-in validation, filtering, and overrides ensure predictable results everywhere. Ready to build? Jump to the [Quick Start Introduction](/?key=quickstart). ### Where can I use ProcBlocks? - ProcBlocks is currently in closed beta at [autobackdrop.com](https://autobackdrop.com) - A public API and SDK is coming soon - For more info, visit [autobackdrop.com/contact](https://autobackdrop.com/contact)