Developed secure user authentication enhancements for the Linkurious/linkurious-rest-client repository, focusing on strengthening backend security and improving user experience. The work introduced robust error handling for invalid authentication parameters and enforced stricter password requirements, directly supporting ongoing security hardening initiatives. Using TypeScript and leveraging API development expertise, the implementation ensured that authentication failures are handled gracefully and that password policies are consistently applied. The feature was delivered as part of the LKE-14453 release, reflecting a methodical approach to backend development. This contribution addressed a critical aspect of user management by reducing authentication vulnerabilities and aligning with organizational security standards.