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

# Unified CRM API

> Unified CRM API for customer relationship management across platforms, with consistent data models for contacts, accounts, and sales workflows.

<Warning>
  **Legacy documentation.** The Legacy Unified APIs are no longer in active development. Existing functionality remains supported, and no new features or enhancements will be added.

  For the current StackOne platform, connectors, and agent tooling, see [docs.stackone.com](https://docs.stackone.com).
</Warning>

## What is a Unified API?

A **unified API** provides a single, standardized interface to interact with multiple third-party providers. Instead of learning each provider's unique API format, authentication scheme, and data model, you write code once, and StackOne handles the differences.

**What StackOne normalizes:**

* **Data models** – Consistent field names and structures across providers (e.g., `files` in Google Drive, SharePoint, and Dropbox all return the same schema; `users` in Google Workspace, Okta, and 1Password all return the same schema)
* **Authentication** – OAuth, API keys, and tokens are managed per-provider; you just pass an `x-account-id` header
* **Pagination** – Cursor-based pagination works the same regardless of whether the provider uses offsets, pages, or cursors
* **Error formats** – Standardized error responses with provider-specific details when available

<Tip>
  **Building AI agents?** Use the [MCP Server](https://docs.stackone.com/embed/call-actions/mcp), an [AI Toolset SDK](https://docs.stackone.com/embed/call-actions/agent-sdk), or the [Actions API (RPC)](https://docs.stackone.com/platform/api-reference/actions/make-an-rpc-call-to-an-action) instead. Same data, optimized for LLM tool calling.
</Tip>

## Benefits of the CRM API

<AccordionGroup>
  <Accordion title="Unified Contact and Account Management" defaultOpen={false}>
    Manage customer contacts and accounts through a single standardized API, regardless of the underlying CRM platforms, ensuring a consistent view of customer data.
  </Accordion>

  <Accordion title="Real-Time Data Synchronization">
    StackOne's APIs support real-time data polling, allowing for immediate updates and synchronization across platforms.
  </Accordion>

  <Accordion title="Privacy-First Design Ensuring Compliance">
    With a [focus on security](https://www.stackone.com/blog/why-your-choice-of-unified-api-could-make-or-break-compliance), StackOne's architecture avoids unnecessary data storage, maintaining compliance with data protection regulations.
  </Accordion>

  <Accordion title="Synthetic and Native Webhooks for Updates">
    The platform provides both [synthetic and native webhooks](/legacy-unified-apis/common-guide/webhooks), enabling real-time notifications for customer and opportunity changes.
  </Accordion>
</AccordionGroup>

## Key Features

The table below shows key features of the CRM API that make customer relationship management easier, from real-time contact tracking to opportunity management:

| **Feature**                      | **Description**                                                                                                        |
| -------------------------------- | ---------------------------------------------------------------------------------------------------------------------- |
| Comprehensive Contact Management | Easily create, update, and retrieve customer profiles, including contact details, interaction history, and engagement. |
| Real-Time Data Synchronization   | Ensure that customer information, sales opportunities, and interactions are updated across systems instantly.          |
| Real-Time Webhooks               | Receive instant notifications for changes in customer profiles, opportunities, or lead statuses.                       |

## StackOne SDKs & OpenAPI Specification

<p class="sdk-text">Use our official SDKs for faster integration. Build with language-native libraries. Full list [here](https://docs.stackone.com/platform-api/api-sdks).</p>

<CardGroup cols={2}>
  <Card title="OpenAPI Specification" icon="link" href="https://api.eu1.stackone.com/oas/crm.json" arrow="true" cta="Click here" />

  <Card title="Popular SDKs" icon="download" class="sdk-card">
    [Node.js](https://www.npmjs.com/package/@stackone/stackone-client-ts)
    [Java (JVM)](https://mvnrepository.com/artifact/com.stackone/stackone-client-java)
    [PHP](https://packagist.org/packages/stackone/client-sdk)
    [Ruby](https://rubygems.org/gems/stackone_client)
  </Card>
</CardGroup>

## Entity Model and Relationships

The following diagram illustrates the key entities within the CRM API:

```mermaid theme={null}
erDiagram
    Contact ||--o{ Account : ""
    List }o--o{ Contact : ""
    List }o--o{ Account : ""

    Contact {
        string id
        string remote_id
        string name
        string address
        string communicationPreferences
        string email
        string phoneNumber
    }

    Account {
        string id
        string status
        string transactionHistory
        date createdAt
        date updatedAt
    }

    List {
        string id
        string name
        string type
        date createdAt
        date updatedAt
    }

```

The following table outlines key entities within the CRM system and provides a brief description of each.

| Entity   | Description                                                                                                              |
| -------- | ------------------------------------------------------------------------------------------------------------------------ |
| Contacts | Manages individual contact details, including names, addresses, and communication preferences.                           |
| Accounts | Handles organizational accounts, encompassing details like account status, associated contacts, and transaction history. |
| Lists    | Manage your custom data lists across your service providers.                                                             |