In finance, the term cosigner denotes a person (or other entity) which signs a binding legal agreement along with one or more other parties.
When a legal agreement is cosigned by more than one person or entity, each of the entities is party to the contract.
Depending on the terms and conditions of the contract in question, cosigners may share equal legal responsibility for the contract, or responsibilities may differ between cosigners.
In Switzerland, it is common for landlords to allow a third party to acts as a cosigner and guarantor of a rental housing agreement. In this arrangement, the cosigner assumes liability to cover any rental payments which are not covered by the renter in keeping with the contract.
Cosigning loan agreements is also common. See the detailed explanation of the term loan cosigner for more information on this use of the term.
Swiss personal loan comparison