> ## 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.

# Instant Classification API

> Classify any company by description or website. Get RTICs, RSICs, RNAICs, SICs, and similar companies in a single call.

Send a company description or a website URL and get back real-time industrial classifications across multiple taxonomies, plus a list of similar companies.

## What you get back

A single `POST` request returns:

| Field | What it is |
| - | - |
| **RTICs** | Real-Time Industrial Classifications: The Data City's proprietary codes that classify companies by what they actually do, updated continuously. |
| **RSICs** | Real-time SIC codes: SIC codes refined with live data rather than the static codes on Companies House. |
| **RNAICs** | Real-time NAICS codes: the North American industry classification equivalent, built the same way as RSICs. |
| **SICs** | Standard Industrial Classification codes: the statutory UK codes registered at Companies House. |
| **Similar companies** | Companies with comparable business activities, ranked by similarity score. |

Most classifications carry a match score, so you can decide how much to trust each result. See the [response reference](https://docs.thedatacity.com/instant-classification/guides/response-reference.md) for what every field contains.

## Who it's for

Use this API when you need to classify companies programmatically: for lead enrichment, portfolio tagging, market sizing, or compliance screening.

## How to get started

> **[Quickstart](https://docs.thedatacity.com/instant-classification/guides/quickstart.md)**
>
> Sign up and classify your first company in under five minutes.

> **[Authentication](https://docs.thedatacity.com/instant-classification/guides/authentication.md)**
>
> OAuth2 password flow: get a JWT, use a Bearer header.

> **[Response reference](https://docs.thedatacity.com/instant-classification/guides/response-reference.md)**
>
> Every field in the response, and when it's empty.

> **[Errors](https://docs.thedatacity.com/instant-classification/guides/errors.md)**
>
> Every error code, what it means, and what to do about it.

> **[Rate limits & quotas](https://docs.thedatacity.com/instant-classification/guides/rate-limits.md)**
>
> Free-tier usage quota and per-minute rate limits.

## Base URL

```text theme={null}
https://instant-classification-api.thedatacity.com/api/v1
```

All endpoints sit under `/api/v1`. The interactive playground on each endpoint page lets you paste your token and send live requests.

<Snippet file="need-help.mdx" />


This documentation is built and hosted on [Mintlify](https://mintlify.com), a developer documentation platform.