Next.js offers to the option to create API endpoints and execute back-end logic without much configuration. All API endpoints that defined are deployed as serverless functions, and are only executed when invoked.

By default, API routes use the Node.js runtime, a JavaScript runtime for running server-side code, to execute logic. Due to this, serverless functions can only be deployed in one region at a time, which might cause end-users to experience higher latency based on their location in the world. Serverless functions may also suffer from cold starts, if they aren't invoked on a regular basis. However, Next.js provides the ability to opt-in to using the Edge runtime to get around some of the downsides to serverless functions. Edge functions will execute code as close as possible to end-users, without suffering from cold starts and increased latency.