Full-code apps

Full-code apps let you build custom frontends with React or Svelte that connect to Windmill backend runnables and data tables. Unlike the low-code app editor, you write your own components and have full control over the UI.

How it works

A full-code app is a directory with the .raw_app suffix (e.g. my_app.raw_app/) or the __raw_app suffix (e.g. my_app__raw_app/) depending on your sync settings. It contains:

• Frontend code: React or Svelte components bundled and served by Windmill
• Backend runnables: scripts in any supported language that run on Windmill workers
• Configuration: a raw_app.yaml file defining metadata, policy and data access

When deployed, Windmill bundles your frontend code and serves it as a single-page application. Your frontend calls backend runnables through an auto-generated wmill.ts module, which communicates with Windmill's execution engine via WebSocket.

Full-code vs low-code apps

	Full-code apps	Low-code apps
UI	Custom React/Svelte components	Drag-and-drop component library
Frontend logic	Full framework features (hooks, stores, routing)	Connecting components + inline scripts
Backend	Scripts in backend/ folder, any language	Runnables panel, inline or workspace scripts
Styling	Your own CSS, Tailwind, etc.	Component-level + global CSS editor
Local dev	wmill app dev with hot reload	Web-based editor only
Best for	Custom UIs, complex interactions, existing codebases	Quick dashboards, forms, CRUD interfaces

Getting started

The fastest way to create a full-code app is with the CLI:

wmill app new

This scaffolds a project with your chosen framework (React or Svelte), a sample backend runnable, and the necessary configuration. Then start the development server:

cd f/folder/my_app.raw_app   # or my_app__raw_app
wmill app dev .

See the CLI workflow page for the full setup guide.

Folder suffix

By default the CLI uses dotted suffixes (.raw_app). If your filesystem or tooling hides dotfiles, set nonDottedPaths: true in your wmill.yaml to use dunder suffixes (__raw_app) instead. All examples in this documentation use the default .raw_app suffix — substitute __raw_app if you enabled non-dotted paths.

Supported languages

Backend runnables support all Windmill script languages:

Language	Extension	Language	Extension
TypeScript (Bun)	.bun.ts or .ts	Python	.py
TypeScript (Deno)	.deno.ts	Go	.go
PostgreSQL	.pg.sql	MySQL	.my.sql
BigQuery	.bq.sql	Snowflake	.sf.sql
MS SQL	.ms.sql	OracleDB	.odb.sql
DuckDB	.duckdb.sql	GraphQL	.gql
Bash	.sh	PowerShell	.ps1
PHP	.php	Rust	.rs
C#	.cs	Java	.java
Ruby	.rb	Nu	.nu
Ansible	.playbook.yml

Pages

Project structure

File layout, raw_app.yaml schema and auto-generated files.

Backend runnables

Define backend scripts called from your frontend code.

Frontend

React and Svelte support, and the wmill.ts API.

Data tables

Whitelist and query Windmill data tables from your app.

CLI workflow

Scaffold, develop and deploy full-code apps from your terminal.

UI editor

Edit full-code apps in the browser.

Deployment

Deploy, configure public access, custom paths and execution policy.