> For the complete documentation index, see [llms.txt](https://docs.lingoql.com/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.lingoql.com/sub0/use-cases.md).

# Use Cases

Sub0 fits when you want production-grade backend behavior without backend sprawl.

You define models, endpoints, validation, auth, and workflows in one system.

### Best fits

#### CRUD and admin backends

Ship internal tools and core product APIs fast.

* Define models once.
* Add validation and auth in the ABI.
* Keep reads and writes predictable.

#### API orchestration and BFFs

Compose database work and external calls behind one endpoint.

* Use action chaining for multi-step flows.
* Shape responses for web and mobile clients.
* Cache expensive reads when needed.

#### SaaS and product backends

Run auth, uploads, jobs, and integrations without framework overhead.

* Start small.
* Keep the same execution model as you grow.
* Avoid rewrites just to reach production.

#### Fintech and workflow-heavy APIs

Model transaction flows, approvals, and follow-up jobs clearly.

* Validate payloads before writes.
* Queue non-blocking work.
* Schedule cleanup or settlement jobs with cron.

#### Internal automation and integrations

Connect services without building a custom worker fleet.

* Call third-party APIs from actionables.
* Receive webhook events.
* Run background tasks after user-facing requests finish.

#### Real-time products

Push updates when state changes.

* Accept websocket requests.
* Protect resources with tokens.
* Broadcast events from actionables.

### Who gets value fastest

* Founders shipping fast without skipping backend discipline.
* Product teams replacing controller-heavy boilerplate.
* Platform teams standardizing how APIs are built.

### The aha moment

A single Sub0 spec can validate input, write data, issue tokens, call external APIs, queue follow-up work, and broadcast updates.

That is the fastest path from idea to a backend that already feels production-ready.

### Start here

* [Getting Started](/sub0/getting-started.md)
* [APIs (ABI)](/sub0/apis-abi.md)
* [Speed up with Sub0 AI](/sub0/speed-up-with-sub0-ai.md)


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