Best Unified API for Read and Write ATS Integrations (2026)

Unified's ATS API simplifies the integration process for recruiting software by providing a consistent interface to multiple Applicant Tracking Systems (ATS), reducing the complexity of dealing with varied authentication, object models, and event delivery methods inherent in individual ATS platforms. By offering a unified schema and endpoint structure, it allows teams to integrate once and interact with normalized ATS objects like candidates, jobs, and applications, while also supporting provider-specific fields for advanced use cases. The API supports typical operations like reading and writing data, subject to provider-specific constraints, and offers event delivery through native or virtual webhooks. It operates as a stateless, pass-through platform, ensuring real-time data access without storing customer records. The ATS API also includes developer tools like SDKs and observability tooling to streamline integration efforts, and it currently supports 68 ATS integrations, including platforms like Greenhouse and Lever. However, the API cannot override limitations on write operations defined by the individual ATS, and these constraints are documented for teams to design features accordingly, ensuring reliable ATS integrations as they scale.