Open-source developer platform for internal code: APIs, background jobs, workflows and UIs. Self-hostable alternative to Retool, Pipedream, Superblocks and a simplified Temporal with autogenerated UIs and custom UIs to trigger workflows and scripts as internal apps.

Scripts are turned into sharable UIs automatically, and can be composed together into flows or used into richer apps built with low-code. Supported languages: Python, TypeScript, Go, Bash, SQL, GraphQL, PowerShell, Rust, and more.

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Windmill - Developer platform for APIs, background jobs, workflows and UIs

Windmill is fully open-sourced (AGPLv3) and Windmill Labs offers dedicated instances and commercial support and licenses.

!Windmill Diagram

https://github.com/user-attachments/assets/d80de1d9-64de-4d89-aacd-6df23fa81fc4

• Windmill - Developer platform for APIs, background jobs, workflows and UIs
• Main Concepts
• Show me some actual script code
• Local Development
• Stack
• Fastest Self-Hostable Workflow Engine
• Security
• Performance
• Architecture
• How to self-host
• Docker compose
• Kubernetes (Helm charts)
• Cloud providers
• OAuth, SSO & SMTP
• License
• Integrations
• Environment Variables
• Run a local dev setup
• Frontend only
• Backend + Frontend
• Contributors
• Copyright

Main Concepts

1. Define a minimal and generic script in Python, TypeScript, Go or Bash that solves a specific task. The code can be defined in the provided Web IDE or synchronized with your own GitHub repo (e.g. through VS Code extension): provided Web IDE or synchronized with your own GitHub repo (e.g. through VS Code extension):

!Step 1

1. Your scripts parameters are automatically parsed and generate a frontend.

!Step 2

!Step 3

1. Make it flow! You can chain your scripts or scripts made by the community shared on WindmillHub.

!Step 3

1. Build complex UIs on top of your scripts and flows.

!Step 4

Scripts and flows can be triggered by schedules, webhooks, HTTP routes, Kafka, WebSockets, emails, and more.

Build your entire infra on top of Windmill!

Show me some actual script code

//import any dependency  from npm
import * as wmill from "windmill-client";
import * as cowsay from "cowsay@1.5.0";

// fill the type, or use the +Resource type to get a type-safe reference to a resource
type Postgresql = {
  host: string;
  port: number;
  user: string;
  dbname: string;
  sslmode: string;
  password: string;
};

export async function main(
  a: number,
  b: "my" | "enum",
  c: Postgresql,
  d = "inferred type string from default arg",
  e = { nested: "object" }
  //f: wmill.Base64
) {
  const email = process.env["WM_EMAIL"];
  // variables are permissioned and by path
  let variable = await wmill.getVariable("f/company-folder/my_secret");
  const lastTimeRun = await wmill.getState();
  // logs are printed and always inspectable
  console.log(cowsay.say({ text: "hello " + email + " " + lastTimeRun }));
  await wmill.setState(Date.now());

  // return is serialized as JSON
  return { foo: d, variable };
}

Local Development

Windmill supports multiple ways to develop locally and sync with your instance:

https://github.com/user-attachments/assets/c541c326-e9ae-4602-a09a-1989aaded1e9

You can run scripts locally by passing the right environment variables for the wmill client library to fetch resources and variables from your instance. See local development docs.

Stack

• Database: Postgres (compatible with Aurora, Cloud SQL, Neon, Azure PostgreSQL)
• Backend: Rust - stateless API servers and workers pulling jobs from a Postgres queue
• Frontend: Svelte 5
• Sandboxing: nsjail and PID namespace isolation
• Runtimes:
• TypeScript/JavaScript: Bun (default) and Deno
• Python: python3 with uv for dependency management
• Go, Bash, PowerShell, PHP, Rust, C#, Java, Ansible

Fastest Self-Hostable Workflow Engine

We have compared Windmill to other self-hostable workflow engines (Airflow,
Prefect & Temporal) and Windmill is the most performant solution for both
benchmarks: one flow composed of 40 lightweight tasks & one flow composed of 10
long-running tasks.

All methodology & results on our
Benchmarks
page.

!Fastest workflow engine

Security

• Sandboxing: nsjail for filesystem/resource isolation, and PID namespace isolation (enabled by default) to prevent jobs from accessing worker process memory
• Secrets: One encryption key per workspace for credentials stored in Windmill's K/V store. We recommend encrypting the Postgres database as well.

See Security documentation for details.

Performance

Once a job started, there is no overhead compared to running the same script on
the node with its corresponding runner (Deno/Go/Python/Bash). The added latency
from a job being pulled from the queue, started, and then having its result sent
back to the database is ~50ms. A typical lightweight deno job will take around
100ms total.

Architecture

How to self-host

For detailed setup options, see Self-Host documentation.

Docker compose

Deploy Windmill with 3 files (docker-compose.yml, Caddyfile, .env):

curl https://raw.githubusercontent.com/windmill-labs/windmill/main/docker-compose.yml -o docker-compose.yml
curl https://raw.githubusercontent.com/windmill-labs/windmill/main/Caddyfile -o Caddyfile
curl https://raw.githubusercontent.com/windmill-labs/windmill/main/.env -o .env

docker compose up -d

Go to http://localhost - default credentials: admin@windmill.dev / changeme

Using an external database: Set DATABASE_URL in .env to point to your managed Postgres (AWS RDS, GCP Cloud SQL, Azure, Neon, etc.) and set db replicas to 0.

Kubernetes (Helm charts)

helm repo add windmill https://windmill-labs.github.io/windmill-helm-charts/
helm install windmill-chart windmill/windmill --namespace=windmill --create-namespace

See windmill-helm-charts for configuration options.

Cloud providers

Windmill works on AWS (EKS/ECS), GCP, Azure, Ubicloud, Fly.io, Render.com, Hetzner, Digital Ocean, and others. Rule of thumb: 1 worker per 1vCPU and 1-2 GB RAM.

OAuth, SSO & SMTP

Configure OAuth and SSO (Google Workspace, Microsoft/Azure, Okta) directly from the superadmin UI. See documentation.

License

The Community Edition is free to use internally. For commercial redistribution or managed services, contact . See LICENSE and Pricing for details.

The "Community Edition" of Windmill available in the docker images hosted under ghcr.io/windmill-labs/windmill and the github binary releases contains the files under the AGPLv3 and Apache 2 sources but also includes proprietary and non-public code and features which are not open source and under the following terms: Windmill Labs, Inc. grants a right to use all the features of the "Community Edition" for free without restrictions other than the limits and quotas set in the software and a right to distribute the community edition as is but not to sell, resell, serve Windmill as a managed service, modify or wrap under any form without an explicit agreement.

The binary compilable from source code in this repository without the "enterprise" feature flag is open-source under the LICENSE-AGPLv3 License terms and conditions.

To re-expose directly any Windmill parts to your users as a feature of your product, with the exception of iframed public Windmill "apps", or to build a feature on top of "Windmill Community Edition" that you sell commercially or embed in a distributable product or binary, you must get a commercial license. Contact us at if you have any questions. To do the same from the binary compiled from the source code in this repository without the "enterprise" feature flag, you must comply with the AGPLv3 license terms and conditions or get a commercial license from Windmill Labs, Inc.

To use Windmill "Community Edition" as is internally in your organization, or to use its APIs as is, you do NOT need a commercial license.

Integrations

In Windmill, integrations are referred to as resources and resource types. Each Resource has a Resource Type that defines the schema that the resource
needs to implement.

On self-hosted instances, you might want to import all the approved resource types from WindmillHub. A setup script will prompt you to have it being synced automatically everyday.

Environment Variables

Run a local dev setup

We recommend using Nix. See ./frontend/README_DEV.md for all options.

Frontend only

Uses the backend of with local frontend (hot-reload):

cd frontend
npm install
npm run generate-backend-client  # or generate-backend-client-mac on Mac
npm run dev

Windmill available at http://localhost/

Backend + Frontend

See the ./frontend/README_DEV.md file for all
running options.

1. Start a local Postgres database using for instance the start-dev-db.sh script which will make a database available at postgres://postgres:changeme@localhost:5432/windmill

Then run the migrations using the following command:

   cargo install sqlx-cli
   env DATABASE_URL=<YOUR_DATABASE_URL> sqlx migrate run

1. (optional, linux only) Install nsjail and have it accessible in

your PATH

1. Install bun, deno and python3 (+ any languages you want to use), have the bins at /usr/bin/bun,/usr/bin/deno, and

/usr/local/bin/python3 or set the corresponding environment variables.

1. (optional) Install the lld linker
2. Go to frontend/:
3. npm install, npm run generate-backend-client then REMOTE=http://localhost:8000 npm run dev
4. You might need to set some extra heap space for the node runtime

export NODE_OPTIONS="--max-old-space-size=4096"

1. Create an empty frontend/build folder using mkdir frontend/build
2. Go to backend/:
3. env DATABASE_URL= RUST_LOG=info cargo run
4. You can specify any feature flag you want to enable, for example cargo run --features python to enable the python executor.
5. Windmill should be available at http://localhost:3000

Contributors

Copyright

© 2023-2026 Windmill Labs, Inc.