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Windmill: Build Internal Tools and Automations for Small Businesses
Stop a small business paying per-seat SaaS fees for every internal tool — build its workflows, dashboards and apps on open-source software you set up and manage for a monthly fee.
Every small business runs on invisible work: the daily report someone copies by hand, the approval that waits in an inbox, the spreadsheet only one person understands. Paying per-seat SaaS fees for each of those jobs adds up fast — and none of it quite fits how the business actually works. Windmill turns that work into tools the business owns.
What Windmill is
Windmill is an open-source, code-first platform for workflows, apps and AI agents — the self-hostable Retool and n8n alternative. With 18,366 GitHub stars, its core is AGPL-3.0, self-hostable with Docker Compose or Kubernetes.
- Scripts become tools: write a small script in Python, TypeScript, Go, Bash, SQL or 20+ languages, and its typed parameters become a form, an API endpoint and a scheduled job.
- Flows chain the work: link scripts into flows with branching, loops, retries and approval steps, so a whole process runs itself.
- Apps on top: build full internal apps — dashboards, admin panels, request forms — on the same scripts and flows.
- AI builds, engineers review: business teams can build with AI in a workspace fork, and changes reach production only after review.
- Triggers everywhere: run work on schedules, webhooks, HTTP routes and emails, with secrets managed centrally.
The service: their internal tools, built and looked after
You self-host Windmill on the client’s own server, set up workspaces and permissions, and build their first workflows and apps — the daily report, the approval flow, the intake form. Then you keep it updated and backed up for a monthly fee, adding tools as needs grow.
Why not just install it themselves? Windmill is code-first: workers, secrets, permissions and uptime all have to be right, and someone has to write and maintain the scripts. A business buys finished tools and the engineer who keeps them working.
Who buys it: ops-heavy teams drowning in manual reports, agencies and trades paying per-seat fees for tools that almost fit, and businesses whose spreadsheet has become a system.
Pricing and costs
A sensible package: $649 one-time setup (hosting, workspaces, permissions and the first three workflows or apps, with staff training) plus $129 a month to manage it. Those are this guide’s suggested prices, not Windmill’s.
| Clients | Monthly recurring | Your hours a month |
|---|---|---|
| 1 | $129 | ~3 |
| 10 | $1,290 | ~20 |
Your costs: self-hosted Windmill Community Edition is $0 (up to 10 users with SSO, plus 100 free app guests every 30 days); the real cost is the server. If a client needs more, Enterprise self-hosting starts at $120 a month, with builders at $20, non-builders at $10 and workers at $50 a month each.
How to find clients
- Ask: “What report, approval or copy-paste job eats an hour a day?” Every answer is a workflow to sell and manage monthly.
- Add up a prospect’s per-seat SaaS bill: one private platform at a flat monthly fee usually makes the pitch.
- Demo with their real work: automate one daily report live, and let the time saved make the argument.
Getting started
- Install Windmill and run your own recurring jobs through it until scripts, flows and schedules are boring.
- Practise the full job — hosting, secrets, permissions, backups and restores — before a client’s operations depend on it.
- Set up one friendly business at a discount, write down the checklist, and make it the standard package.
Watch-outs
- Licence: Windmill’s core is AGPL-3.0 — modify it and offer it over a network, and you owe users the modified source. Enterprise features are proprietary, and Community Edition terms bar selling or serving it as a managed service, so install it on the client’s own instance and read the current terms first.
- Code-first means real code: a client still needs someone technical to own the specs and review changes — don’t sell it as a no-code tool.
- Workflows touch real systems: use least-privilege credentials, separate dev and production workspaces, and review AI-built code before it deploys.
- These systems hold business data: get written permission for the systems you connect, and keep backups and an audit trail.
Sources
- Windmill on GitHub (18,366 stars; AGPL-3.0), checked November 3, 2026
- Windmill pricing (Community $0; Enterprise from $120/month), checked November 3, 2026
- Windmill documentation, checked November 3, 2026