A Salesforce developer is a person who builds applications for the platform as a service. They don't have to actually work for the company. Developers are also responsible for various tasks related to the development of applications for salesforce. They are knowledgeable about the platform, but they are not limited to its technical expertise. They might also be involved in other areas such as configuration and customization.

Most developers who work with Salesforce technologies build custom business apps and solutions. They do this either with the Salesforce Platform (including Sales Cloud, Service Cloud, and Experience Cloud communities) or with Heroku. While some developers specialize, most fit the description of full-stack developers working with both back-end logic and front-end experiences.

A Salesforce developer is a programmer who builds Salesforce applications across various PaaS (Platform as a Service) platforms. They don't have to actually work for Salesforce, by the way.