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How to obtain AmberTools23

AmberTools is a free, useful standalone package and a prerequisite for installing Amber itself. The AmberTools suite is free of charge, and its components are mostly released under the GNU General Public License (GPL). A few components are included that are in the public domain or which have other, open-source, licenses. The libsander and libpbsa libraries use the LGPL license.

The Reference Manual is available in pdf format, and included in the distribution. It may help you to see if AmberTools meets your needs.

Option 1: Binary distribution via conda

The conda package-management system can install a serial, binary (pre-compiled) distribution. This should work for Linux and MacOS systems, and may be sufficient for many users. It provides a simple way to get started with AmberTools, and to install it into many workflows. It does not provide access to parallel or GPU-enabled options, and the full source-code distributions are needed if you wish to combine AmberTools with Amber.

To install, proceed as follows:

  • If you don't have conda installed, please visit the Miniconda download page.

  • Those with an existing conda installation may wish to create a new conda "environment" to avoid conflicts with what you already have installed. To do this:

      conda create --name AmberTools23
      conda activate AmberTools23

    (Note that you would need to perform the "conda activate" step every time you wish use AmberTools23 in a new terminal; it might be appropriate to add this to your start-up script. Creating a new environment should not be necessary if you only use conda for AmberTools.)

  • Once this is done, type:

      conda install -c conda-forge ambertools=23

  • AmberTools is updated from time to time. To keep your conda package up-to-date, do this:

      conda update -c conda-forge ambertools

Thanks to Jaime Rodríguez-Guerra for spearheading this.

Option 2: Upgrading from an AmberTools22 source code installation

If you already have an AmberTools22 source code installation, do this:

  cd amber22_src
  ./update_amber --upgrade

Then follow the instructions to re-build the installation.

Option 3: Getting source code in tar format

This path is the traditional way AmberTools has been distributed. AmberTools is distributed in source code format, and must be compiled in order to be used. You will need C, C++ and Fortran90 compilers.

To download version 23 of the AmberTools distribution, please fill in the following form and click the "Download" button. The file size you should get is about 543 MB, and the md5sum is 073deadb3edfa96f86da91e3b070d2bc.

Note: Installation instructions are in Chapter 2 of the Amber 2023 Reference Manual. More detailed instructions for many systems may be found at the OS-specific requirements page.



How to obtain Amber22

Amber22 facilitates faster simulations (on parallel CPU or GPU hardware) and is distributed with a separate license and fee structure. Here is the license:

AMBER22 Software License

GRANT OF LICENSE. The Regents of the University of California grants, and you hereby accept, a permanent, non-exclusive license to use the Amber 22 software product ("Software") to the extent of its rights and in accordance with the terms of this Agreement. This licensed copy of the Software may only be used by you and members of your organization at your site who have read and agreed to this license. You may install the Software on computers at your site, or at other locations, provided that reasonable steps are taken to restrict use of the software to you and members of your organization. You may not distribute copies of the Software to others outside of your organization, and may make only those copies of the Software which are necessary to install and use it as permitted by this Agreement, or are for purposes of backup and archival records.

OWNERSHIP. This ownership is protected by the copyright laws of the United States and by international treaty provisions. Upon expiration or termination of this Agreement, you shall promptly terminate use of the Software and accompanying written materials.

MODIFICATIONS AND DERIVATIVE WORKS. You may modify the software, and use it to create derivative works, for your internal use at the site covered by this license. You may not distribute such modified or derivative software to others outside of your site without written permission. You may distribute the modifications themselves (e.g. as "patches") under terms of your choice. We encourage users to contribute modifications back into Amber, but you are under no obligation to do so.

ASSIGNMENT RESTRICTIONS. You shall not use the Software (or any part thereof) in connection with the provision of consultancy, modeling or other services, whether for value or otherwise, on behalf of any third party who does not hold a current valid Amber 22 Software License Agreement. You shall not rent, lease, or otherwise sublet the Software or any part thereof. You may transfer on a permanent basis the rights granted under this license provided you transfer this Agreement and all copies of the Software, including prior versions, and all accompanying written materials. The recipient must agree to the terms of this Agreement in full and register this transfer with the University of California.

LIMITED WARRANTY. LICENSEE acknowledges that LICENSORS make no warranty, expressed or implied, that the program will function without error, or in any particular hardware environment, or so as to generate any particular function or result, and further excluding any other warranty, as to the condition of the program, its merchantability, or its fitness for a particular purpose. LICENSORS shall not be liable for any direct, consequential, or other damages suffered by the LICENSEE or any others as a result of their use of the program, whether or not the same could have been foreseen by LICENSORS prior to granting this License. In no event shall LICENSORS liability for any breach of this agreement exceed the fee paid for the license.

UNIVERSITY OF CALIFORNIA'S LIABILITY. In no event shall the University of California be liable for any indirect, special, or consequential damages, such as, but not limited to, loss of anticipated profits or other economic loss in connection with or arising out of the use of the software by you or the services provided for in this Agreement, even if the University of California has been advised of the possibility of such damages. The University of California's entire liability and your exclusive remedy shall be, at the University of California's discretion, to return the Software and proof of purchase to the University of California for either (a) return of any license fee, or (b) correction or replacement of Software that does not meet the terms of this limited warranty.

NO OTHER WARRANTIES. The University of California disclaims other implied warranties, including, but not limited to, implied warranties of merchantability or fitness for any purpose, and implied warranties arising by usage of trade, course of dealing, or course of performance. Some states do not allow the limitation of the duration or liability of implied warranties, so the above restrictions might not apply to you.

Getting Amber22 for non-commerical use

Read the above license: note it contains restrictions on usage and redistribution.

By filling out this form, you agree to the license, and confirm that all use will be non-commerical. Note that there is no license fee for non-commerical use.



Please note: You must also download and untar AmberTools23 using options 2 or 3, as described above.

Getting Amber22 for commerical use

The license above is valid for both commerical and non-commerical usage. Only the license fee is different from commerical use. Commerical users should fill out this application for a commerical license. This will generate a license form that you can sign, and will contain information about how to pay the license fee.

Once payment is received, an email will be sent to the address you provide, containing a username and password, along with instructions on how to download the software.

Please note: The Amber22 license is a site license, valid for any number of users and any number of computers. The computers may be located anywhere (such as in the "cloud", or at remote computing centers.) Basically, the license deals with the affiliation of the users, and not with the location of the computing equipment itself.

Also note: Each release of Amber (which happens every two years) is treated as separate product, and requires a new license form and a new fee.


  • Academic/non-profit/government: $0. Use the "non-commerical" form, above.
  • Industrial (for-profit): $25,000 for new licensees, $20,000 for licensees of Amber 18 or Amber20.
  • Porting and demonstration licenses are available, as are licenses for computing centers: see the License Agreement for details.
  • Users who license Amber20 after January 1, 2022 are eligible for a free upgrade to Amber22. (This is not automatic: if you wish to obtain the new version, you need fill out and submit a new License Agreement, indicating that you are eligible for the upgrade.)

"How's that for maxed out?"

Last modified: Sep 18, 2023