Materials and Methods Software Development In validation tests using previously reported cases, SnackVar correctly identified all types of variants when trace files of appropriate quality were given, requiring a shorter time for analysis than a commercial software package. SnackVar can run on all types of major platforms and operating systems because it is written in Java, which is known for its platform independence. When both forward and reverse traces are available (which they commonly are), the two traces are compared with each other to filter out false variant calls. When multiple equivalent descriptions exist for an indel variant, the one at the most 3′ position is reported, following the 3′ rule of HGVS. All kinds of sequence variants, including complex indel variants (eg, deletion/insertion variant with hundreds of indel sizes), can be reported in the correct format of the HGVS nomenclature. A coding DNA reference is applied simply by typing in a Reference Sequence (RefSeq) NM number or by searching RefSeq from a gene name. SnackVar enables users to detect variants from trace files with minimum user interaction. SnackVar (, last accessed June 22, 2020), a graphical user interface–based software, was developed for the easy detection of variants with Sanger sequencing in clinical laboratories. We expect SnackVar to be a cost-effective option for clinical laboratories performing Sanger sequencing. Compared with commercial software, SnackVar required less than one-half of the time taken for the analysis of a selected set of test cases. The cause of one incorrect variant calling was proven to be erroneous base callings from poor-quality trace files. Among 88 previously reported variants from four insertion/deletion–rich genes ( BRCA1, APC, CALR, and CEBPA), the result of SnackVar agreed with reported results in 87 variants. The featured reference sequences of all of the genes are prestored in SnackVar, allowing for detected variants to be precisely described based on coding DNA references according to the nomenclature of the Human Genome Variation Society. All types of variants, including heterozygous insertion/deletion variants, can be identified by SnackVar with minimal user effort. In this study, SnackVar (, last accessed June 22, 2020), a novel graphical user interface–based software for Sanger sequencing, was developed. However, recent developments in the field of bioinformatics have focused mostly on next-generation sequencing, while tools for Sanger sequencing have shown little progress. Despite the wide application of next-generation sequencing, Sanger sequencing still plays a necessary role in clinical laboratories.