Kysely

Kysely is a TypeScript library for building SQL queries with full type checking. It is not an ORM: you think in tables and joins, but the compiler knows which tables and columns are in scope at each point of a query and what shape the result rows will have.

The model is small. You give the Kysely constructor a TypeScript interface describing your database's tables, plus a dialect, the adapter for one database engine. Built-in dialects cover PostgreSQL, MySQL, SQL Server, SQLite and PGlite, and community dialects add Postgres.js, serverless drivers for PlanetScale and TiDB, Cloudflare Durable Objects and others. Queries are chained method calls that compile to SQL. Kysely infers columns and aliases even through subqueries and CTEs; a sql template tag covers the rest.

What you get: transactions, including controlled ones with savepoints; helpers such as jsonArrayFrom that fetch nested objects and arrays in a single query; a plugin system that hooks into query compilation and results; and a built-in migrator that runs ordered up and down functions. It is mainly developed for Node.js but also runs on Deno, Bun and in browsers, where it can compile SQL without a connection.

Limits: Kysely has no relations or models, so no automatic eager loading or change tracking. It does not create your schema types for you either; you write them by hand or generate them with third-party tools such as kysely-codegen or prisma-kysely. Migrations are code you write, not diffs generated from a schema.