> ## Documentation Index
> Fetch the complete documentation index at: https://docs.thedatacity.com/llms.txt
> Use this file to discover all available pages before exploring further.

# Industry Engine API

> REST API for The Data City Industry Engine. Every v2 endpoint, with a live playground.

Access classifications, financials, growth signals, and group structure for UK companies. The REST API exposes the same data that powers Industry Engine — same coverage, same definitions, fresh on the same cadence.

Authenticate with a Bearer token, send JSON, get JSON back.

<CardGroup cols={2}>
  <Card title="Quickstart" icon="rocket" href="/api-reference/guides/quickstart">
    Make your first request in under five minutes.
  </Card>

  <Card title="Authentication" icon="key" href="/api-reference/guides/authentication">
    How Bearer tokens work and where to get one.
  </Card>

  <Card title="Errors" icon="triangle-exclamation" href="/api-reference/guides/errors">
    The error envelope and status-code matrix.
  </Card>

  <Card title="Rate limits" icon="gauge-high" href="/api-reference/guides/rate-limits">
    200 requests per minute, with backoff guidance.
  </Card>
</CardGroup>

## Working with lists

<CardGroup cols={2}>
  <Card title="Pagination" icon="arrows-left-right" href="/api-reference/guides/pagination">
    `returnCount` and `skip` — defaults, maximums, patterns.
  </Card>

  <Card title="Filtering" icon="filter" href="/api-reference/guides/filtering">
    Build a list with RTICs, CICs, or your own portfolio.
  </Card>

  <Card title="Batching" icon="layer-group" href="/api-reference/guides/batching">
    Bulk endpoints and company-number sets for large lists.
  </Card>
</CardGroup>

## Reference

Every operation is documented under the **Endpoints** group in the sidebar. Each page includes a live playground — paste your token, fill the parameters, send the request.

Base URL:

```text theme={null}
https://product-api.thedatacity.com/api
```

All current endpoints are under `/v2/...`. See [Versioning](/api-reference/guides/versioning) for the policy and [Changelog](/api-reference/guides/changelog) for what's changed.

## For LLMs and agents

The full v2 surface is also available as a single curated text file optimised for LLM context. Paste it into ChatGPT/Claude or feed it to an agent for end-to-end API context in one request.

<Card title="llms.txt — full API reference (one file)" icon="robot" href="https://product-api.thedatacity.com/api/documentation/llms.txt">
  Endpoint decision tree, request/response shapes, idiomatic patterns. Regenerated on every API deploy.
</Card>