Windmill
Windmill is an open-source platform that turns scripts into endpoints, workflows and UIs. It seeks to remove boilerplate by generating interfaces and workflows around existing code
Platform features
- Script-driven model. Write scripts in TypeScript, Python, Go, PHP, Bash, C#, SQL or Rust; Windmill infers dependencies, creates lockfiles and JSON schemas, then serves minimal UIs automatically
- Visual flow editor. Compose scripts into workflows with retries, error handling, loops, branching, suspending flows and approval steps
- Low-code UI builder. Build dashboards and admin panels using inline scripts and trigger flows from the UI
- Enterprise readiness. Features include RBAC permissions, secret management, OAuth handling, CLI/git sync, scheduling and webhooks
- Use cases. Deploy scripts as webhooks or cron jobs; create “applicative workflows” combining external APIs; build ETLs and interactive dashboards
- Open source & self-hosting. Windmill emphasises an open-source codebase and self-hosting options
Comparison with ContractSpec
| Feature | Windmill | ContractSpec |
|---|---|---|
| Entry model | Write scripts; platform auto-generates UI and workflows | Define typed specs (Capabilities, DataViews, Workflows, Policies); compiler outputs back-end, front-end and forms. |
| Language support | 20+ languages via embedded runtimes | Uses TypeScript/JavaScript for providers; supports other back-ends through capability providers. |
| UI generation | Minimal UI forms from script parameters; low-code app builder | Generates full web and mobile UIs from specs; user layouts can be customised via signed overlays. |
| Policy & personalization | RBAC and secret management; no per-user overlay concept | Built-in policy engine enforcing ABAC/PII on every render/mutate; overlays allow safe per-user customisation. |
| Open source | Fully open source and self-hostable | Closed-source core (SDK is open); offers hosted and on-prem modes. |
| Ideal for | Teams wanting to expose scripts as APIs, workflows or dashboards without heavy infrastructure. | Teams needing a spec-driven platform that generates code and UI, enforces policies and lets non-technical users tailor the experience. |
Windmill excels at converting scripts into workflows and admin panels. ContractSpec takes a spec-first approach, generating the entire stack and enforcing policies, making it suitable for long-lived applications that must evolve safely.