UCSF Chimera is a program for the interactive visualization and analysis of molecular structures and related data, including density maps, trajectories, and sequence alignments. It is available free of charge for noncommercial use. Commercial users, please see Chimera commercial licensing.

We encourage Chimera users to try ChimeraX for much better performance with large structures, as well as other major advantages and completely new features. ChimeraX includes a significant subset of Chimera features (with more to come, see the missing features list) and is under active development. Users may choose to use both programs, and it is fine to have both installed.

Chimera is no longer under active development, and is only updated for critical maintenance. Chimera development was supported by a grant from the National Institutes of Health (P41-GM103311) that ended in 2018.

Feature Highlight

Nucleotides

Special representations of DNA and RNA can be displayed with the Nucleotides tool or the command nucleotides. Different levels of abstraction are available. The figure shows a ribbon backbone combined with the following sidechain (sugar/base) options:

• ladder rungs
• filled-ring atomic representations
• "lollipops" in which bases are shown as ellipsoids and sugars as tubes

Bases can also be displayed as boxes or elliptical tubes, with or without bumps to indicate orientation. The colors of the special representations will update automatically to match the corresponding atoms.

(More features...)

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Gallery Sample

Annotated Green Fluorescent Protein

BILD format was used in Chimera to annotate the barrel structure of green fluorescent protein with its centroid, major axis (red arrow), and an enclosing cylinder (shown with green hoops). The BILD file green.bild was generated with the python program green.py using the coordinates in green.pdb. Gallery entry courtesy of Mike Ess, Yeast Resource Center, University of Washington. (More samples...)