Morpheus is a mass spectrometry–based proteomics database search algorithm designed from the ground up for high-resolution tandem mass spectra. We have discovered that for high-resolution MS/MS, simple spectrum preprocessing and scoring performs superior to more complex algorithms originally developed for low-resolution MS/MS, such as Sequest, Mascot, and OMSSA. Morpheus is also very fast—up to nearly 5 times faster than OMSSA for large human datasets. It is written in C# and is available open source under the permissive MIT License.
