Skip to main content

​
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., employees in BambooHR, Workday, and Personio 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 MCP Servers or AI Toolset SDKs instead. Same underlying data, optimized for LLM tool calling with built-in context management.

​
Legacy Unified APIs

The Legacy Unified APIs provide standardized access to various business system categories. Each API follows the same patterns for authentication, pagination, and error handling, but exposes domain-specific data models.

HRIS

Human Resources Information Systems - manage employees, time-off, benefits, and organizational data

ATS

Applicant Tracking Systems - manage candidates, jobs, applications, and hiring workflows

CRM

Customer Relationship Management - manage contacts, accounts, and sales data

LMS

Learning Management Systems - manage courses, content, assignments, and completions

Accounting

Accounting Systems - manage accounts, transactions, and financial data

​
Common Features Across All APIs

All Legacy Unified APIs share these common features:
FeatureDescription
AuthenticationAll APIs use the same authentication method with API keys and x-account-id headers
PaginationConsistent cursor-based pagination across all endpoints
Synthetic IDsStackOne Identifiers work the same way across all APIs
Rate LimitingSame rate limiting policies apply to all endpoints
Error HandlingStandardized error codes across all APIs

​
Getting Started

  1. Set up authentication - Get your API key from the dashboard and learn about authentication
  2. Connect an account - Use StackOne Hub to connect your first provider
  3. Make your first request - Follow the “Making your first request” guide for your chosen API
  4. Explore common features - Learn about pagination, field mapping, and advanced query parameters

​
Next Steps

Pagination

Learn how to paginate through large datasets

StackOne Identifiers

Understand synthetic IDs and how to use them

Field Mapping

Map custom fields between your system and providers

Webhooks

Set up real-time notifications for data changes