Gusto

Gusto is a US-focused payroll, benefits, and HR platform with a REST API designed for integration partners building HR workflow products. Its API covers employee records, payroll processing, benefits administration, and time tracking — the core data surfaces needed by agents automating HR operations or aggregating people data across systems. Teams building HR automation that touches US payroll specifically find Gusto's API the primary programmatic path to their employees' compensation and benefits data.

The Partner API covers companies, employees, contractors, payrolls, benefits, compensations, and time-off policies. Agents can read employee demographic and employment data, retrieve payroll run history with gross/net breakdowns, access benefits enrollment status, and query time-off balances. Write operations include onboarding new employees and updating compensation records — enabling agents to automate HR lifecycle workflows.

Authentication uses OAuth 2.0 for partner integrations — agents obtain tokens through the standard OAuth flow with the customer's consent, granting access to their specific company data. The OAuth model is appropriate for multi-tenant HR tools where each customer authorizes access to their own Gusto data. Gusto's developer sandbox provides test company data without needing a live customer.

Reliability is production-grade for a payroll platform. Gusto maintains the availability requirements for payroll processing, which has strict timing dependencies. Teams building payroll-dependent automation should implement appropriate retry logic for Gusto API errors, particularly during payroll processing windows when API load may be elevated.

Documentation covers the employee, payroll, and benefits APIs with clear data model explanations. The OAuth integration guide is thorough for partner developers. Teams evaluating Gusto versus Rippling or Deel for HRIS API integration should compare the payroll data depth and the geographic coverage — Gusto is US-only, while Rippling and Deel support international workforce management.