Effect
TypeScript library for typed errors, concurrency, and dependency injection
What it is
Effect is a TypeScript library that models programs as typed values, bringing together typed error handling, dependency injection, structured concurrency, retry scheduling, schema validation, and built-in tracing in one toolkit. The monorepo also ships platform packages for Node.js, Bun, Deno, and the browser, plus SQL clients for PostgreSQL, MySQL, SQLite, ClickHouse and others, and AI provider modules. TypeScript developers reach for it when building backend services and long-running applications that need predictable failure handling and observability.