Use FLink to input a list of up to 100,000 protein sequence (or gene or small molecule) identifiers and retrieve a ranked list of up to 100,000 biosystems. More information and illustrations are available in the FLink documentation:

• About FLink
• Illustrated quick start guide (example: proteins → biosystems)
• Textual step-by-step guide (example: proteins → biosystems)

Although FLink was initially developed as a companion tool for the BioSystems database, it can also be used in a similar way for other types of input and output data (see the list of FLink's supported databases).