Jean-David Bonicel

Posted on Apr 17

I built a CLI that scaffolds complete multi-tenant SaaS apps

#react #java #webdev #opensource

After building the same multi-tenant platform architecture over and over -- React shell, micro-frontends, Spring Boot backends, API gateway, shared UI kit, tenant isolation, auth -- I decided to automate it.

apps-generator is a Python CLI that scaffolds a complete full-stack tenant app from a few commands. You describe your resources, and it generates everything: backend CRUD with tenant isolation, typed API client, data-fetching frontend pages with charts, Docker Compose, Kubernetes manifests, and CI/CD pipelines.

What it generates

6 templates that wire together automatically:

platform-shell -- React host app with Module Federation, Clerk/OIDC auth, org switcher, i18n (EN/FR)
frontend-app -- React micro-frontends with data-aware pages (list tables, create forms, dashboards with Recharts)
api-domain -- Spring Boot 3 backends with DDD architecture, PostgreSQL, Hibernate tenant filter, CRUD from resource schema
api-gateway -- Spring Cloud Gateway with JWT validation, tenant header forwarding, correlation IDs
api-client -- Typed TypeScript fetch client shared across all MFEs, with auto-generated types from resource schema
ui-kit -- 26 shadcn/ui components + Recharts charts + Storybook

How it works

# Generate infrastructure
appgen generate ui-kit -o ./ui-kit -s projectName=my-ui-kit
appgen generate api-client -o ./api-client -s projectName=my-api-client
appgen generate api-gateway -o ./gateway -s projectName=my-gateway \
  -s basePackage=com.example.gateway

# Generate a backend with CRUD resources
appgen generate api-domain -o ./product-service \
  -s projectName=product-service \
  -s basePackage=com.example.products \
  -s 'resources=[{
    "name": "product",
    "fields": [
      {"name": "name", "type": "string", "required": true},
      {"name": "price", "type": "decimal", "required": true},
      {"name": "stock", "type": "integer"}
    ]
  }]' \
  --gateway ./gateway --api-client ./api-client

# Generate the shell + a micro-frontend with pages
appgen generate platform-shell -o ./shell -s projectName=my-platform \
  --uikit ./ui-kit --api-client ./api-client

appgen generate frontend-app -o ./products -s projectName=products \
  -s 'pages=[
    {"path":"dashboard","label":"Dashboard","resource":"product","type":"dashboard"},
    {"path":"list","label":"Products","resource":"product","type":"list"},
    {"path":"new","label":"New Product","resource":"product","type":"form"}
  ]' \
  --shell ./shell --uikit ./ui-kit --api-client ./api-client

# Generate Docker Compose and start everything
appgen docker-compose .
docker compose up --build

Open http://localhost and you have a working multi-tenant app with auth, CRUD, tenant isolation, charts, and i18n.

What makes it different

Tenant isolation at the ORM level

Every entity extends TenantAwareEntity which has a Hibernate @Filter that automatically adds WHERE tenant_id = :tenantId to every query. Even findAll() is tenant-scoped. You cannot leak data across tenants.

Resource schema is the single source of truth

You define fields once in JSON. The CLI generates:

Java entity with JPA annotations
Spring Data repository with tenant-scoped queries
Service layer with CRUD operations
REST controller with validation
Create/Update/Response DTOs with Bean Validation
Liquibase database migration
Integration test with Testcontainers
TypeScript interfaces in the shared API client

Backend and frontend types match by construction -- no manual sync needed.

Data-aware pages

When you specify "type": "list" or "type": "form" on a page, the generator creates a real component with data fetching:

List pages get a shadcn Table with pagination and useQuery
Form pages get typed inputs with validation and useMutation
Dashboard pages get stat cards and Recharts bar charts

Everything wires together

--shell registers MFEs in the shell's remotes.json
--gateway registers routes in the gateway's routes.yaml
--uikit links the shared component library with the Tailwind theme
--api-client generates TypeScript types and links the shared fetch client

No manual configuration between projects.

The stack

Layer	Technology
Shell	React 18, Module Federation, Clerk/OIDC, i18next
MFEs	React 18, Vite, TanStack Query, TypeScript
UI Kit	26 shadcn/ui components, Recharts, Tailwind CSS, Storybook
Gateway	Spring Cloud Gateway, JWT, correlation IDs, security headers
Backend	Spring Boot 3, JPA/Hibernate, PostgreSQL, Liquibase, Testcontainers
Infra	Docker Compose, Kubernetes (Kustomize), GitHub Actions CI/CD

Built-in security

Correlation ID tracing across the full stack (shell -> gateway -> backend)
Security headers: CSP, X-Frame-Options, X-Content-Type-Options, Referrer-Policy
CORS configuration with environment-based allowed origins
OAuth2/JWT validation with dev escape hatch (@Profile("local"))
Structured error responses with correlation IDs for debugging

Open source

The project is GPL v3 and on GitHub:

https://github.com/jeandbonicel/apps-generator

89+ automated tests
Full EN/FR i18n support
Comprehensive docs covering architecture, security, multi-tenancy, and deployment
Contribution guide with PR templates and CI on every PR

If you build multi-tenant SaaS apps and are tired of scaffolding the same architecture every time, give it a try. Feedback and contributions welcome.

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