MDTraj is a python library that allows users to manipulate molecular dynamics (MD) trajectories and perform a variety of analyses, including fast RMSD, solvent accessible surface area, hydrogen bonding, etc. A highlight of MDTraj is the wide variety of molecular dynamics trajectory file formats which are supported, including RCSB pdb, GROMACS xtc, tng, and trr, CHARMM / NAMD dcd, AMBER binpos, AMBER NetCDF, AMBER mdcrd, TINKER arc and MDTraj HDF5.