Windmill
Open-source developer platform and workflow engine
About Windmill
Windmill is an open-source platform to build, deploy, and monitor internal tools from scripts. It turns scripts into auto-generated UIs, APIs, cron jobs, and workflows with sub-20ms overhead, supporting Python, TypeScript, Go, Bash, SQL, and more. It positions itself as an alternative to Retool, n8n, Airflow, and Temporal.
Pros & Cons
Pros
- Fastest open-source workflow engine with sub-20ms overhead per step
- True open source (AGPLv3) and fully self-hostable avoiding vendor lock-in
- Multi-language flexibility supporting 9+ languages natively plus Docker images
- Code-first with low-code option balancing developer control with accessibility
- Generous free tier with unlimited executions and up to 50 users
- Automatic dependency management reducing DevOps overhead
Cons
- Steep learning curve with the UX being daunting for newcomers
- Self-hosted deployments require more technical expertise upfront
- Small company with 10-22 employees, raising long-term stability concerns
- Primarily designed for developers, not ideal for business-user-heavy teams
Key Features
Multi-Language Script Editor
Write and execute scripts in Python, TypeScript, Go, PHP, Bash, SQL, Rust, or any Docker image with full LSP support
Workflow Orchestration
Build DAG-based workflows with conditional branches, parallel execution, for-loops, and sub-20ms per-step overhead
Low-Code App Builder
Drag-and-drop editor to create data dashboards and internal apps combining visual components with code
Auto-Generated UIs
Automatically generates user interfaces for scripts and flows based on their parameters
Scheduling & Triggers
Run scripts on schedules, via webhooks, CLI, Slack commands, or email triggers with full monitoring
Self-Hosting & Open Source
Fully open-source (AGPLv3) and self-hostable with complete control over data and infrastructure
Enterprise Security
Granular RBAC, SSO/SAML, secret management, OAuth, audit logs, and SOC 2 compliance
Git Integration & Local Dev
Develop locally with VS Code extension and CLI, sync with Git, deploy through CI/CD
Monitoring & Observability
Real-time execution logs, performance tracking, alerts, and OpenTelemetry exports
Managed Dependencies
Automatic lockfile generation and dependency management across all supported languages
Pricing
- Unlimited executions
- Up to 50 users
- 3 workspaces
- Community Discord support
- Enterprise features at reduced price
- For companies <10 employees
- Self-hosted only
- Priority support
- Base + $20/developer + $10/operator
- Audit logs
- SAML
- 24/7 priority support
- Dedicated Slack channel
- Git sync
Best For
Internal Tool Development
Rapidly build admin panels and operational tools by turning backend scripts into applications with auto-generated UIs
Data Pipeline Orchestration
Orchestrate ETL/ELT workflows across databases, APIs, and file storage with DAG-based flows
IT & DevOps Automation
Automate infrastructure tasks, CI/CD pipelines, monitoring alerts, and incident response workflows
Business Process Automation
Build approval flows, notification systems, and cross-service integrations with human-in-the-loop steps
AI Agent Orchestration
Chain AI/ML model calls, data preprocessing, and result handling into reliable automated workflows
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Best for engineering teams that need workflows, scripts, and internal tools on one platform. Windmill replaces not just Zapier but also Retool and custom cron job infrastructure. Self-hosted is free and truly unlimited.