Best Unified API for ATS Integrations in 2026

Unified.to is a leading unified API platform that supports 85 Applicant Tracking System (ATS) integrations, offering the largest ATS catalog among unified APIs, and operates on a pass-through architecture that does not store candidate data. The platform is designed to address common challenges in ATS integrations, particularly the complexities involved in writing data back into various ATS platforms, which often have varied and restrictive write rules. Unified.to provides a public capability matrix detailing readable and writable fields and webhook events for each integration, offering transparency that aids in evaluating integration capabilities before committing to development. Other unified API platforms like Merge, Kombo, Apideck, Knit, and Truto are also mentioned, each with different strengths, such as Merge's mature enterprise option with over 50 ATS integrations and Apideck's transparency in listing supported operations. The assessment of these platforms emphasizes the importance of understanding which specific objects can be written to, how event delivery is managed, particularly for ATS platforms without native webhooks, and the implications of data storage architecture on compliance and security. Unified.to's approach to integration extends beyond ATS to cover the entire hiring lifecycle, including integrations for HR, background checks, and assessments, providing a comprehensive solution for recruiting products that require consistent application and candidate data across different systems.