Vendor lock-in is a situation in which a customer is dependent on a vendor for products and services and cannot move to another vendor without substantial costs. It is often used in the computer industry to denote the lack of compatibility between different systems which intentionally or unintentionally forces a customer to continue to use products and services from a particular vendor.

Open standardization processes are meant to provide a way to reduce the risk of vendor lock-in when creating new standards.

One argument for open source software is that it greatly reduces vendor lock-in. Many people accuse Microsoft of intentionally fostering vendor lock-in, and some extend that to all monopolies.