Methods and systems are disclosed for flexibly managing lock modes in a data-sharing environment, including optimistic and pessimistic lock modes. A lock mode determination service receives a request from an application instance for a lock mode with which to access specified data objects. The service can determine and provide a suitable lock mode based on a context of the application, and optionally other parameters, by evaluating a checklist of criteria sorted in precedential order. Criteria can include geo-boundaries, platform, role, and others. The requesting application instance uses the determined lock mode to access the data, with optional assistance of a lock service. The lock mode determination service can support one or more applications having one or more instances each, and can also support multiple disjoint data-sharing environments. Suitable environments include cloud, datacenter, mobile, client-server, and SAAS.