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This section explains why Activepieces works the way it does: the components, the execution model, and the trade-offs behind them. If you want to do something (size a deployment, set up SSL, scale workers), start with Configure & Operate. Come here when you want the reasoning under those choices. This page describes the main components, with a focus on how flows run.

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Components

Activepieces production architecture: client, app, Redis job queue, Postgres, S3, and one-flow-per-worker execution tier Activepieces:
  • App: The main application that organizes everything from APIs to scheduled jobs.
  • Worker: Polls for new jobs, allocates a sandbox from the pool, executes the flows with the engine inside the sandbox, and sends results back to the app.
  • Sandbox: An isolated execution environment that manages process lifecycle, resource limits, and communication with the engine via WebSocket.
  • Engine: TypeScript code that parses flow JSON and executes it. It is compiled into a single JS file and runs inside the sandbox.
  • UI: Frontend written in React.
Third Party:
  • Postgres: The main database for Activepieces.
  • Redis: Powers the queue using BullMQ.

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Reliability & Scalability

Postgres and Redis availability is outside the scope of this documentation, as many cloud providers already implement best practices to ensure their availability.
Everything is queue-backed: webhooks and recurring jobs land on Redis, and workers poll them off it. A spike does not drop work. It queues and drains as slots free. For exactly what survives a crash, what runs at-least-once, and where each promise stops, see Guarantees. To scale Activepieces, add replicas of the workers, the app, or the Postgres database. A small Redis instance is enough: it handles thousands of jobs per second and rarely becomes a bottleneck. For the concrete sizing model, see Production Setup.

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Repository Structure

The repository is a monorepo built with Turbo, with TypeScript as the primary language. It is divided into several packages:
  • web: This package contains the user interface, implemented using the React framework.
  • api: This package contains the main application written in TypeScript with the Fastify framework.
  • worker: This package contains the logic of accepting flow jobs and executing them using the engine.
  • server-sandbox: This package contains the sandbox execution environment, including process isolation, pool management, and WebSocket communication between the worker and engine.
  • common: This package contains the shared logic between worker and app.
  • engine: This package contains the logic for flow execution within the sandbox. Located under server/engine.
  • pieces: This package contains the implementation of triggers and actions for third-party apps.
  • shared: This package contains shared data models and helper functions used by the other packages.
  • ee: This package contains features that are only available in the paid edition.