execbox
Execbox is a Node.js 22+ library for running guest JavaScript against
host-defined tools and MCP tool catalogs. It gives you a small provider model in
@execbox/core and a QuickJS executor in @execbox/quickjs that can run inline
or in a worker thread.
Start by defining one provider, run it with QuickJS, then decide whether your application should keep QuickJS inline or move it off the main thread.
Install
Section titled “Install”npm install @execbox/core @execbox/quickjsSmallest example
Section titled “Smallest example”Use Getting Started to define one host tool, resolve it
with @execbox/core, and call it from guest JavaScript through
QuickJsExecutor.
Packages
Section titled “Packages”| Package | Use it for |
|---|---|
@execbox/core | Provider contracts, schema validation, and MCP adapters |
@execbox/quickjs | Inline and worker-hosted QuickJS execution |
Read next
Section titled “Read next”- Getting Started - install execbox and run the smallest QuickJS flow
- Providers & Tools - design host tool namespaces, schemas, and result boundaries
- Runtime Choices - choose between inline and worker-hosted QuickJS execution
- Examples - run the main example flows from the repo
- MCP Integration - wrap upstream MCP tools or expose execbox as MCP tools
Understand
Section titled “Understand”- Security & Boundaries - understand the capability boundary and deployment guidance
- Architecture - review the package and execution model
- Performance - compare runtime placement and pooling tradeoffs