Gap4 is a part of the Staden package of sequence assembly, editing and analysis tools.

Gap4 performs assembly, contig joining, assembly checking, repeat searching, experiment suggestion, read pair analysis and contig editing. It has graphical views of contigs, templates, readings and traces which all scroll in register. Contig editor searches and experiment suggestion routines use phred confidence values to calculate the confidence of the consensus sequence and hence only identify places requiring visual trace inspection or extra data. The result is extremely rapid finishing and a consensus of known accuracy.

See also infomation about pregap4, spin and trev.