Licensing ClustalW and ClustalX

Date:29 November 2007

The copyright for ClustalW and ClustalX is held by Des Higgins, Julie Thompson and Toby Gibson

The binaries and source code are made available and can be distributed subject to the following 

Users are free to redistribute ClustalW or ClustalX in it's unmodified form as long as it is not 
for commercial gain.

Anyone wishing to redistribute Clustal commercially should contact Toby Gibson at

If users make changes/have ideas that they believe would be useful to the broader research 
community they can send their suggestions to the clustal development team at where 
they will be considered for inclusion in future releases.

Frequently asked questions about Clustal licensing?

1. Do I have to pay to use ClustalW or ClustalX?
No - unless you wish to redistribute Clustal for profit. In this case see question 4.

2. Can I redistribute the Clustal binaries and source code?
Yes. We have always wanted to see Clustal have as wide a userbase and distribution network as 
possible and are happy to see other sites host copies of the official Clustal code.

3. Can I make changes to the source code?
You can make changes for your own purposes but you should not redistribute the changed code.

4. I want to include ClustalW/ClustalX in a commercial application who should I contact?
Toby Gibson at (also cc

5. There is no Clustal distribution for platform X. I have changed the code in order to compile 
Clustal on this platform. Can I redistribute it?
Ideally you should send us a copy of your source code changes as well as a binary. We will include 
it in our contributed binaries section on our FTP site along with an acknowledgement of your 

Thank you!