n8n: Open-Source Workflow Engine Positioned as a Self-Hosted Zapier Alternative

n8n is a Node.js workflow automation tool that users run on their own infrastructure, in contrast to Zapier, which is a rented hosted service. The article notes that it has no per-task metering and avoids vendor lock-in, and that a low-cost virtual private server can handle substantial workloads. Its Code node lets users write custom JavaScript or Python when visual building is insufficient. The piece then examines the internal execution model, describing a single serializable run object, a stack-based scheduler, and a waiting map that holds partial inputs until a multi-input node is ready to run. It also explains how the executionOrder setting (v0 or v1) changes whether scheduling is breadth-first or depth-first.