SQLite is a popular and fast database engine. While it can't be used with Vercel, we do offer other storage solutions like Vercel Postgres instead.
SQLite needs a local file system on the server to store the data permanently when write requests are made. In a serverless environment, this central single permanent storage is not available because storage is ephemeral with serverless functions. As a function receives more concurrent traffic, the serverless environment will create new instances of the function and each instance will not be able to share the same storage.
One alternative to SQLite that can be used with Serverless Functions is Vercel Postgres.
Vercel Postgres is a serverless, fully-managed relational database built on PostgreSQL and designed to work with any frontend framework. You can get started with Vercel Postgres today in minutes with one of our many templates.