Windmill

Windmill is an open-source workflow engine and developer platform for building internal software. It best suits teams that want to combine code, low-code workflows and app builders, with self-hosting as an option. Its broad language support and generous free-plan workspace and user caps make it a flexible starting point, while Enterprise adds commercial licensing and priority support.

Overview

Windmill brings scripts, workflows and interfaces into one platform for engineering, data, sales, support and marketing teams. Developers can write scripts in TypeScript, Python, Go, PHP, Bash, C#, SQL, Rust, Ruby and R, among other languages; teammates can also use the low-code flow builder and low-code app builder. React and Svelte app builders offer another route when teams want to build interfaces with those frameworks.

That range is useful for teams building internal tools across technical and operational functions, but it asks them to choose the right building approach for each job. Windmill’s self-hosted option gives teams deployment flexibility; it also makes security configuration worth careful attention, since PID namespace isolation is disabled by default and NSJAIL sandboxing is optional.

Key features

Build and trigger work

Scripts and flows can run from webhooks, schedules, HTTP routes, queues or the open API. That variety lets teams connect automated work to both external events and internal services. Reusable workflows and a hybrid workflow builder support combining code with visual construction rather than forcing every task into one style.

Integrations and development

Windmill’s Hub includes more than 200 resource types, including GitHub, Slack, AWS, BigQuery and PostgreSQL. Teams can also define custom resource types through schemas with fields and constraints, which is valuable when their systems are not covered by a ready-made resource. Local development through the CLI and Git sync support version control and deployment workflows.

Enterprise features include granular permissions, role-based access control, secret management, OAuth, single sign-on and audit logs. These capabilities matter for teams managing access across internal applications; organizations relying on isolation should explicitly assess the default-disabled PID namespace isolation and optional NSJAIL sandboxing.

Pricing

Windmill uses a freemium model, with a free self-hosted plan and Enterprise from $120/mo. The Enterprise trial lasts one month.

The free plan’s 50-user allowance and three workspaces give small teams room to build and share internal tools without a subscription, but guest app use is capped at 100 users per 30 days and storage at 10 GiB per workspace. Enterprise is the fit for organizations that need commercial licensing, uncapped SSO or a defined priority-support response. Its SSO requires seats, so the uncapped SSO benefit does not mean seats are free.

Platforms

Windmill supports API, Linux, self-hosted, web and Windows environments. Self-hosting is a meaningful option for teams that want to run the platform themselves, while API and web support suit software that needs to connect services and internal interfaces.

Who it's for

Windmill is a strong fit for teams building internal software that want scripting, workflow orchestration and app construction in one developer platform. Engineering and data teams can work directly in supported languages; sales, support and marketing teams can also be served through low-code flows and apps. It is less compelling for organizations unwilling to manage self-hosted security settings or those whose needs require stronger isolation by default.

Pros and cons

• Pros: Broad language support and multiple builders let teams choose between scripts, low-code flows and app interfaces rather than standardizing on one approach.
• Pros: Webhooks, schedules, routes, queues and an open API provide several ways to trigger work.
• Pros: The free plan includes 3 workspaces and 50 users, with a self-hosted option and community support.
• Cons: Free guest apps are limited to 100 users per 30 days, and each workspace has 10 GiB of object storage.
• Cons: PID namespace isolation is off by default and NSJAIL sandboxing is optional, requiring security-conscious teams to review configuration.
• Cons: Enterprise SSO requires seats, and the paid plan starts at $120/mo.

Alternatives

For a tightly capped free integration setup, Celigo offers 2 endpoints, 1 flow and 1 production environment on its free plan; choose it when those limits suit the work better than Windmill’s broader internal-software toolkit. n8n is a self-hosted alternative with a Community Edition available through GitHub, worth considering when a self-hosted option is the priority.

Google Cloud Application Integration offers a free tier with up to 400 integration executions and up to 20 GiB of data processed per month, making it an option when those integration quotas fit the workload. Nango has a free plan with 10 connections, 10 compute hours per month and 10GB of data transfer per month; choose it when those connection and transfer limits match the need.

Apache Camel is a free option for Linux, Windows and macOS. SnapLogic is a paid web-based alternative with Essential, Professional and Enterprise One plans. Jitterbit Harmony is a paid option available on web, Windows and Linux, with plan tiers that differ in connections and support response. Oracle Integration is a paid API and web alternative with a free trial and Standard and Enterprise plans offering 5,000 messages per hour.

For broader category comparisons, see API Integration Platforms, IT Orchestration Software, Task Automation Software, Workload Automation Software, Workflow Orchestration Software and Internal Tools Software.

Verdict

Choose Windmill if your team wants a self-hostable platform that combines code, low-code workflows and internal app builders, with a free plan large enough for 50 users across three workspaces. Its strongest reasons to look elsewhere are the free guest-app and storage caps, the paid entry point of $120/mo, and security isolation settings that require deliberate review.