Synthetic biology has garnered significant global interest owing to its diverse applications in bio-based production, biosensing, living therapeutics, and drug delivery. This heightened interest has increased the demand for novel protein synthesis methods and genome-scale assemblies. However, gene assembly from oligomers presents several challenges, including the risk of incorrect assembly between oligomers, self-annealing, and the potential for insertions or deletions resulting from misannealed oligomers. Dsembler (DNA Assembly Designer) is a web-based software application designed to assemble long DNA sequences. It provides a set of oligomers with optimal melting temperatures and GC overlap, which facilitates a commercially available oligomer pool service. By enhancing the accuracy of oligomer design, Dsembler has addressed critical challenges in synthetic biology and supported advancements in genetic engineering and molecular biology.