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

# Retention.com Data APIs

> Powerful APIs to supercharge your existing stack, that you can rely on and scale with.

## Get Started!

> [card] [API reference](https://retention.mintlify.site/reference/introduction.md)
>
> Every endpoint, grouped by what you start with — email/HEM, IP, or LinkedIn.

## The APIs

> [card] [Core Identity](https://retention.mintlify.site/reference/introduction.md)
>
> Pass in a HEM; enrich it with three shapes of person-level data: Universal, Personal (B2C), Professional (B2B).

> [card] [HEM → Business Profile](https://retention.mintlify.site/api-reference/hem/hem-to-business-profile.md)
>
> Hand us a HEM, get a B2B profile back. Optional mobile-phone second hop.

> [card] [Identity Resolution](https://retention.mintlify.site/api-reference/ip/ip-to-hem.md)
>
> Resolve an IP/UA into a HEM, mobile ad IDs, or company data.

> [card] [LinkedIn lookups](https://retention.mintlify.site/api-reference/linkedin/linkedin-to-business-profile.md)
>
> Resolve a LinkedIn profile into a business profile, hashed emails, or a mobile phone.

> [!NOTE]
>
> Most endpoints accept a **HEM** — a 32-character hashed email (MD5) — or a plaintext email.

## Authentication

Send your API key in a request header on every call. Any of these work:

```bash theme={null}
Api-Key: YOUR_API_KEY
# or
X-Api-Key: YOUR_API_KEY
# or
Authorization: Bearer YOUR_API_KEY
```

To find your key, log in to the [dashboard](https://ui.api.rb2b.com) and click **API key** at the top of the page. Keep it secret: it authenticates every request and draws down your account's credits.


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