Effect#

Effect is a library for building robust, maintainable, type-safe, and production grade applications in TypeScript. It helps you handle the hard problems at scale: typed errors, dependency injection, structured concurrency, scheduling, tracing, and unified schema validation.

Effect 4.x is a long-term support (LTS) release. If you are upgrading from Effect 3.x, follow the migration guide.

Installation#

npm install effect

Requirements#

• TypeScript 5.9 or newer. TypeScript 7 is recommended for the best performance and compatibility with Effect's TypeScript tooling.
• Node.js 22.19 or newer is the general minimum for running Effect on Node.js.
• Strict type-checking: the strict flag must be enabled in your tsconfig.json.

Links#

• Website: documentation, guides, and news
• Discord: ask questions, share what you're building, and talk to the core team
• Community: meetups and events, or bring Effect to your own
• Issues: bug reports and feature requests
• Jobs: companies hiring Effect developers
• Follow us on X, Bluesky, and LinkedIn

Let's talk#

Whether your team is considering Effect, rolling it out, or already running it in production, we'd love to hear from you: what you're building, what works, and what you need from Effect next.

• Talk to the maintainers. Introduce your team on Discord or email contact@effectful.co. We're happy to connect privately on Slack or Discord for feedback and help with adoption.
• Production support. We're exploring how to better support teams running Effect in production. If your organization has specific support needs, let's discuss them.
• Adoption help. Our adoption partners offer implementation, consulting, team extension, training, and commercial support.

Feedback from teams using and evaluating Effect directly shapes what we stabilize and build next.

Long-term support#

Teams depend on Effect for systems they expect to run for years. Effect 4.x is a long-term support (LTS) release with the following guarantees:

• At least three years of support, including bug and security fixes.
• Bug fixes for one year after the next major version is released.
• Security fixes for two years after the next major version is released.

Stable APIs reserve breaking changes for major releases. APIs marked unstable may change in minor releases, and experimental APIs may change in patch releases.

Effect v3#

The Effect v3 source code is available on the v3 branch, which is also where issues and pull requests meant for Effect v3 should be targeted. To upgrade, see the migration guide.

Packages#

This monorepo contains the core effect package alongside integration packages that extend it. All packages listed below are released together with synchronized versions.

Package	Description	API Reference
effect	The core package	docs
@effect/platform-browser	Platform services for the browser	docs
@effect/platform-bun	Platform services for Bun	docs
@effect/platform-deno	Platform services for Deno	docs
@effect/platform-node	Platform services for Node.js	docs
@effect/platform-node-shared	Shared services for Node.js-compatible runtimes	docs
@effect/sql-clickhouse	SQL client for ClickHouse	docs
@effect/sql-d1	SQL client for Cloudflare D1	docs
@effect/sql-libsql	SQL client for libSQL	docs
@effect/sql-mssql	SQL client for Microsoft SQL Server	docs
@effect/sql-mysql2	SQL client for MySQL	docs
@effect/sql-pg	SQL client for PostgreSQL	docs
@effect/sql-pglite	SQL client for PGlite	docs
@effect/sql-sqlite-bun	SQL client for SQLite via bun:sqlite	docs
@effect/sql-sqlite-do	SQL client for Cloudflare Durable Objects SQLite	docs
@effect/sql-sqlite-node	SQL client for SQLite via node:sqlite	docs
@effect/sql-sqlite-react-native	SQL client for SQLite in React Native	docs
@effect/sql-sqlite-wasm	SQL client for SQLite compiled to WebAssembly	docs
@effect/ai-anthropic	Anthropic provider for the Effect AI modules	docs
@effect/ai-openai	OpenAI provider for the Effect AI modules	docs
@effect/ai-cloudflare	Cloudflare decision provider for the Effect AI modules	docs
@effect/ai-typesafe	TypeSafe decision provider for the Effect AI modules	docs
@effect/ai-openai-compat	OpenAI-compatible API provider for the Effect AI modules	docs
@effect/ai-openrouter	OpenRouter provider for the Effect AI modules	docs
@effect/atom-react	React bindings for Effect Atom	docs
@effect/atom-solid	SolidJS bindings for Effect Atom	docs
@effect/atom-vue	Vue bindings for Effect Atom	docs
@effect/opentelemetry	OpenTelemetry integration	docs
@effect/vitest	Helpers for testing with Vitest	docs
@effect/docgen	Documentation generator for Effect projects	docs
@effect/doctest	Runs JSDoc examples as Vitest tests	docs
@effect/openapi-generator	Generate Effect code from OpenAPI specifications	docs
@effect/graphql-generator	Generate Effect code from GraphQL documents	docs

License#

MIT