Choosing a sync source

appctl does not add a new CLI flag for every web framework. Long-term, that does not scale: each stack would need its own parser and tests. What scales is a small set of machine-readable inputs plus an extension point (plugins) for special cases.

Recommended paths

You have…	Use	Details
An OpenAPI 2/3 (or Swagger) document	appctl sync --openapi	Nest (@nestjs/swagger), Spring / springdoc, FastAPI, ASP.NET (often emits JSON), and many other stacks can expose a spec. Point --openapi at a URL or file.
Only a database and SQL access	appctl sync --db	Introspection from information_schema (or equivalent) for supported engines. No HTTP layer required.
An MCP server (HTTP)	appctl sync --mcp	Model Context Protocol tools map 1:1. Good when the app already exposes an MCP surface or a bridge.
Something else	Dynamic plugin	Rust cdylib that implements the plugin SDK. Use when there is no spec and you need custom discovery.
A browser-only or legacy HTML app	appctl sync --url	Crawl + forms (limited; prefer an API with OpenAPI when you can).

Built-in framework flags (Django, Rails, Laravel, …) exist for projects that do not yet expose OpenAPI: appctl reads project files to build a best-effort contract. When you can export OpenAPI, prefer --openapi so tools match what the server actually documents.

Stacks without a dedicated flag (examples)

Ecosystem	Practical approach
Next.js (App Router, Route Handlers)	Export or generate an OpenAPI document from your API route layer (or a BFF) and sync --openapi. If you only have server actions with no spec, use --db or --mcp if you wrap the backend.
NestJS	Use @nestjs/swagger and the generated JSON/YAML: --openapi to that file or URL.
Java / Spring Boot	Use springdoc (or similar); typically /v3/api-docs (often listed automatically when you pass a root base URL to --openapi—see OpenAPI).
Ruby (not using the Rails sync)	If you use a gem that serves OpenAPI, use --openapi. Otherwise --db or a plugin.
gRPC	No first-class gRPC sync today; use a sidecar that exposes gRPC or REST, or a plugin.

Why this is enough

• One OpenAPI path matches how API gateways, gateways, and clients (Postman, Insomnia, code generators) already work: contract-first.
• MCP is the “bring your own tool server” path that does not require appctl to know your repo layout.
• Plugins keep odd integrations out of the core binary while still being first-class in the sync command.

See also

• OpenAPI / Swagger — including authenticated fetch and common paths
• Introduction — sync sources (summary)
• appctl sync