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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.

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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
Building AI agents? Use the MCP Server, an AI Toolset SDK, or the Actions API (RPC) instead. Same data, optimized for LLM tool calling.

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Benefits of the CRM API

Manage customer contacts and accounts through a single standardized API, regardless of the underlying CRM platforms, ensuring a consistent view of customer data.
StackOne’s APIs support real-time data polling, allowing for immediate updates and synchronization across platforms.
With a focus on security, StackOne’s architecture avoids unnecessary data storage, maintaining compliance with data protection regulations.
The platform provides both synthetic and native webhooks, enabling real-time notifications for customer and opportunity changes.

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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:

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StackOne SDKs & OpenAPI Specification

Use our official SDKs for faster integration. Build with language-native libraries. Full list here.

OpenAPI Specification

Popular SDKs

Node.js Java (JVM) PHP Ruby

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Entity Model and Relationships

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