VIPER (Visual Inspection of Peak/Elution Relationships) can be used to visualize and characterize the features detected during LC-MS analyses. It is primarily intended for processing deisotoped data from high mass measurement accuracy instruments (e.g. FT, TOF, or Orbitrap) and comparing the features found to a list of expected peptides (aka mass and time (MT) tags), as practiced by the AMT tag approach.