Overview
Windmill is a fast, open-source developer platform that turns scripts (Python, TypeScript, Go, Bash, SQL) into workflows, internal tools, and scheduled jobs. It combines a flow editor, an app/UI builder, and a job runner with a Rust execution backend for performance. It overlaps with both iPaaS automation and internal-tool builders like Retool.
Key features
- Turns scripts in Python, TypeScript, Go, Bash, and SQL into reusable jobs and steps
- Flow editor for chaining steps into multi-stage workflows with branching and retries
- App/UI builder for assembling internal tools and admin panels on top of scripts
- Scheduled jobs and cron-style triggers for recurring automation
- Rust execution backend running the job queue and workers
Our take
Windmill is a strong fit if your team thinks in scripts: it covers a lot of ground that would otherwise need both Zapier-style automation and a Retool-style internal-tool builder, and the Rust backend gives it genuinely fast job execution. The breadth is also the catch — flows, the app builder, and the job runner are three sizable products in one, so expect a learning curve and some operational surface area to manage. Self-hosting is well supported across Docker Compose and Kubernetes, and a managed option exists if you'd rather not run the workers and queue yourself. Note the AGPL-3.0 license, which matters if you plan to offer a modified version as a network service. For developer teams comfortable writing code, it's one of the more capable options in this space; non-technical users will get less out of it.
Ideal for: Developer-leaning teams who want to build internal tools and automations in real code rather than clicking through a low-code GUI.
Where it falls short of Zapier
- Code-first approach is more developer-oriented than Zapier's pure no-code experience.
- AGPL plus a separate enterprise edition; some features (distributed workers at scale, SSO, audit) are gated.
- Fewer turnkey SaaS connectors; you often write the integration glue yourself.
- Self-hosting requires Postgres and worker configuration for real workloads.
We list the gaps honestly so you can decide if the trade-off is worth owning your data.
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