Windmill

Open SourceOtherSelf-hostable

The open-source developer platform that turns TypeScript, Python, Go and Bash scripts into production workflows, cron jobs and internal apps — powered by one of the fastest execution engines in automation.

Open source alternative to

n8n

Retool

Visit Windmill View source

About Windmill

Windmill starts from a different premise than visual automation tools: developers already know how to express logic — in code. So instead of dragging nodes, you write a TypeScript, Python, Go or Bash script and Windmill instantly turns it into a runnable workflow step, a scheduled job, a webhook endpoint or an internal app with an auto-generated UI.

Under the hood is a Rust execution engine that benchmarks among the fastest in the category, with queues, retries, error handling and approval steps built in. A visual flow editor exists too — but every flow remains code you can version, review and test like the rest of your stack.

Self-host the whole platform with Docker or use Windmill Cloud. For teams that outgrew n8n's node canvas or don't want to pay Retool per seat for internal tools, Windmill covers both jobs with one AGPL-licensed platform.

Key features

Scripts become workflows — Write TypeScript, Python, Go or Bash — Windmill wraps it with a UI, schedule, webhook and permissions automatically.
Flows + internal apps — Chain scripts into flows with retries and approvals, or drag an app UI over them for your team.
Rust-fast engine — One of the fastest workflow engines measured — thousands of jobs per second on modest hardware.
Self-host with Docker — Full platform on your infrastructure, with SSO, permissions and audit logs on the enterprise tier.

How to install Windmill

The honest read

What we like

Code-first: workflows are versionable, testable scripts
Extremely fast Rust execution engine
Also replaces internal-tool builders like Retool
Generous open-source core (AGPL-3.0)
Very active development and responsive team

Worth knowing

Requires developers — not for no-code users
AGPL license needs review for embedded commercial use
Smaller integration library than n8n's 400+ nodes
UI density takes a few sessions to learn

FAQ

Is Windmill free to use?

Yes — Windmill's core is open source under AGPL-3.0 and free to self-host without seat limits. Windmill Cloud has a free tier, and paid plans add SSO, audit logs and support.

How is Windmill different from n8n?

n8n is visual-first: you build workflows by wiring nodes. Windmill is code-first: you write scripts and it handles the workflow plumbing — scheduling, retries, UIs and permissions. Developers who find node canvases limiting usually prefer Windmill.

Can Windmill replace Retool?

Largely, yes. Windmill auto-generates UIs from scripts and includes a drag-and-drop app builder, so internal dashboards and admin panels can live on the same platform as your automations.

Can I self-host Windmill?

Yes — a docker-compose stack (server, workers, Postgres) runs the whole platform. It's the standard way teams deploy it.