https://www.epo.org/en/node/how-can-i-create

How can I create sequence listings compliant with WIPO Standard ST.26?

Besides some commercially available products, WIPO's free WIPO Sequence software can help you to create sequence listings compliant with WIPO Standard ST.26.

You are free to use any XML-editing tool you like to produce your sequence listing as long as it complies with WIPO Standard ST.26 at the time of filing, However, WIPO Standard ST.26 is complicated, and so it is strongly recommended that you only use software specifically designed for this purpose.