Output-only analysis for system identification (SI) has increasingly become a central topic in resent research due to its ability to obtain dynamic characteristics of a structure using only the responses without requiring any information about input excitation. This paper introduces a novel approach called NExT-LF which is an input-output system identification based on rational interpolation known as Loewner Framework (LF) combined with Natural Excitation Technique (NExT) which can be used for Structural Health Monitoring (SHM) and Operational Modal Analysis (OMA). Comparative analyses are conducted between NExT-LF and the established system identification technique Eigensystem Realization Algorithm (NExT-ERA) on both numerical and case study datasets to assess capability and performance differences in various conditions.