User interface commands for regular expression generation

Techniques for generated regular expressions are disclosed. In some embodiments, a regular expression generator may receive input data comprising one or more character sequences. The regular expression generator may convert character sequences into a sets of regular expression codes and/or span data structures. The regular expression generator may identify a longest common subsequence shared by the sets of regular expression codes and/or spans, and may generate a regular expression based upon the longest common subsequence. Generation of the regular expressions can be implemented on an interactive user interface. Commands can be applied to the one or more character sequences and regular expressions are generated based on the applied commands.