The most prominent spatially correlated errors in GNSS observations are well known to be atmospheric effects. The ionosphere and troposphere are the two main layers of the Atmosphere that cause delays in GNSS observations. A linear combination of the dual-frequency data can be used to reduce ionospheric delay. Unlike the ionospheric delay, the tropospheric delay cannot be eliminated using the same methods. The troposphere is primarily associated with GPS. The delay it causes in GPS signals is regarded as one of the primary sources of errors that must be eliminated to determine accurate positions. This paper's main purpose is to develop a new source code that can estimate the effect of tropospheric delay over any GPS station. The tropospheric delay in this proposed code is estimated utilizing sequential least-squares adjustment using a model depending on Niell Mapping Function (NMF). This model, known as the Tropospheric Delay Estimation program, was created in the MATLAB® environment (TDE). This research presents the results of tropospheric delay during DOY 2, 2020 of actual data from ten ground-based IGS stations distributed over Antarctica, China, Canada, Fiji, Russia, Greenland, and Portugal IGS stations worldwide. For validation of the proposed code results, they were compared with troposphere delay results of the International GNSS Service (IGS). Good agreement and high correlation were found between both results. In comparison to IGS, the proposed code's standard deviations range from 0.0000525 m to 0.008154 m, indicating how accurate this study is in terms of agreement of solutions provided by IGS. Finally, the MATLAB software can accurately estimate troposphere delay with an adaptable temporal resolution for GPS users.