Appsmith vs Windmill
Both are alternatives to Retool. Here's how they stack up — verified facts, no spin.
Also searched as Windmill vs Appsmith — same comparison, one verdict.
Appsmith
TOP PICKThe closest open equivalent — drag, drop, connect, self-host.
Appsmith is the most direct open replacement for Retool: a drag-and-drop builder with widgets, JavaScript anywhere, and connectors for the major databases and APIs. It self-hosts with Docker or Kubernetes and the core is Apache-2.0, which is the most permissive licence of the serious options here. Around 40.6k stars. If your reason for reading this page is per-builder pricing, this is the first thing to try, and the conceptual jump from Retool is small enough that an existing Retool user is productive quickly.
Windmill
For teams whose internal tools are mostly scripts and workflows.
Windmill takes the opposite approach to a drag-and-drop canvas: you write scripts in Python, TypeScript, Go or Bash and Windmill generates the UI from their inputs, alongside a workflow engine for chaining them. For an engineering team whose internal tooling is fundamentally automation with a form on top — reruns, backfills, ops jobs — that is a much better fit than a widget canvas. AGPL-3.0 core with a commercial enterprise edition. Roughly 17.5k stars, and unusually fast because the execution engine is Rust.
Side by side
| Appsmith | Windmill | |
|---|---|---|
| Sovereignty Score | 90 | 88 |
| Open source | Yes | Yes |
| Self-hostable | Yes | Yes |
| Local-first | Yes | Yes |
| License | Apache-2.0 (core; some enterprise features are commercial) | AGPL-3.0 (core; enterprise edition is commercial) |
| Pricing | Free and open source to self-host. Paid cloud and enterprise tiers. | Free and open source to self-host. Paid cloud and enterprise editions. |
Appsmith is Macrostack's recommended Retool alternative, so it's our pick here.
Appsmith
Strengths
- +Closest feature match to Retool of anything open
- +Apache-2.0 core — the most permissive licence among serious options
- +Self-hosts on Docker or Kubernetes with no per-builder fee
- +Large widget library and broad database connector support
Trade-offs
- −Some governance and SSO features sit behind the paid tier
- −Fewer third-party integrations than Retool out of the box
- −You now operate a service, including upgrades and backups
- −Polish trails Retool in places, particularly complex state
Windmill
Strengths
- +Script-first: the UI is generated from code you already write
- +Serious workflow engine, not an afterthought
- +Rust execution engine — genuinely fast
- +Fits engineering teams better than a drag-and-drop canvas
Trade-offs
- −Wrong shape if you want non-engineers building tools
- −AGPL-3.0 strong copyleft
- −Smaller community than Appsmith or ToolJet
- −UI generation is less flexible than hand-placed widgets
Related alternative guides
Facts verified 2026-08-07. Licenses and pricing change — spotted something out of date? That's a correction we want.