Field level security in CRM is used to restrict individuals/teams on using selected fields. It allows the administrator of the CRM system to change security permissions on individual fields that include Read, Create and Update. This is one of the most efficient ways of controlling access and permissions within the workplace. There are a number of CRM software that offers filed level security. It can turn to a hot debate on which is the best, but unarguable options are
Microsoft Dynamics CRM: It is one of the popular CRM software that offers a high degree of functionality and customization. Using Microsoft Dynamics CRM, one can limit the access of a certain number of fields to specific individuals or can even change the permissions if needed. Note, that this can only be enabled for custom created fields and are not available for built-in (system) default fields.
Zoho CRM that offers field level security right within the application. This setting can be applied if you want to hide a specific field from one user group while allowing other groups to have access to the same or you can simply give read-only access.