Migrating from Jenkins to Harness Continuous Integration (CIE) significantly improved performance and developer productivity by addressing issues such as Jenkins' memory surge, long queue wait times, and scheduling delays. The transition, which involved a team of 170 developers and took about a month, included planning, executing Proof of Concept (PoC) tests, and identifying job owners. Key challenges included categorizing jobs, developing a backup strategy, and ensuring team collaboration. The migration led to a 20% increase in developer productivity and unified CI/CD pipelines, enhancing visibility and efficiency. The process involved thorough job analysis, backups, and collaboration among multiple teams, ultimately resulting in the successful migration of 167 jobs while shutting down Jenkins. CIE offered simpler configurations, better access controls, and more flexibility, such as running multiple stages in different containers, which Jenkins did not support.