# Effect-TS/effect

Build production-ready applications in TypeScript

Repository: https://github.com/Effect-TS/effect
Canonical: https://ross.abutalabs.com/products/effect
Homepage: https://effect.website
Language: TypeScript
License: MIT
License Family: permissive
Topics: effect, javascript, cli, opentelemetry, platform, schema, typescript, dependency-injection, error-handling, observability, clustering, concurrency, workflows
Last push: 2026-08-27T00:23:34+00:00

## Health v2 (maintenance only)
Score: 94/100 (v2, computed 2026-09-03T02:39:23.370411+00:00)
- activity 99, release rhythm 83, longevity 100
- inputs: {"age_days": 2485, "days_push": 7, "days_rel": 34, "gap_med": 0, "n_releases_24m": 6388}
- flags: none
- formula: round(0.45*activity + 0.35*rhythm + 0.20*longevity); archived -> min(score, 10)

## Adoption (not part of the score)
Stars 15514, forks 696 (observed 2026-08-28T04:11:09.975446+00:00)

## What it is
Effect is a TypeScript library and ecosystem for building production-grade, type-safe applications, centered on the Effect type that encodes success, errors, and requirements as composable values. It provides typed errors, structured concurrency, dependency injection, retries, resource safety, schema validation, and built-in observability, with platform, SQL, AI, and reactivity integration packages.

## Use cases
- handle errors in TypeScript with types instead of try/catch
- run concurrent tasks with bounded parallelism and cancellation
- add retries with exponential backoff to flaky operations
- do dependency injection in TypeScript with type-safe services
- build CLIs and HTTP servers in TypeScript
- validate and parse data with schemas
- add tracing and structured logging to a Node.js app
- integrate LLM providers like OpenAI and Anthropic in a typed app

## When to choose
- you are building a large or long-lived TypeScript codebase where reliability, typed errors, and composability matter
- you need structured concurrency, resource safety, and observability out of the box
- you want a consistent ecosystem (HTTP, SQL, CLI, AI) built on one core
- your team is willing to invest in learning a functional-effect style

## When to avoid
- small scripts or prototypes where the learning curve and runtime overhead are not justified
- teams that cannot adopt a non-idiomatic, functional programming style in TypeScript
- bundle-size-critical frontend code where even the Micro module may be too heavy
- codebases that must stay on plain Promise/async-await conventions

## Facets
- artifact type: library
- maturity: stable
- function: error-handling, concurrency, middleware, logging, tracing, monitoring, serialization, cli, http-server, http-client, workflow-automation, scheduling, configuration-management, sdk
- domain: developer-tools, backend, web-development, apis, large-language-models, databases, microservices, cross-platform
- platform: bun, browser, cross-platform, wasm
- tags: functional-programming, typed-errors, dependency-injection, structured-concurrency, resource-safety, schema-validation, observability, opentelemetry, effect-system, monorepo, streams, reactivity, nodejs, deno, typescript

## Member repositories
- Effect-TS/effect (main) score 94

## Provenance
- Observed fields: from GitHub, fetched 2026-08-28T04:11:09.975446+00:00.
- Health v2: computed from the inputs above; adoption is never an input.
- Inferred fields (summary, facets, guidance): AI-extracted, prompt v1, taxonomy v1, on 2026-08-29T17:05:43.887809+00:00, confidence not recorded.
  - readme: https://github.com/Effect-TS/effect (fetched 2026-08-28T04:11:09.975446+00:00, sha 47bfe5022af5)
  - homepage: https://effect.website (fetched 2026-08-29T08:04:18.177778+00:00, sha 4c50f38d2e31)
  - site_page: https://www.effect.website/docs/v4 (fetched 2026-08-29T08:04:18.181087+00:00, sha 995def3abf9a)
  - site_page: https://www.effect.website/docs/v4/api (fetched 2026-08-29T08:04:18.183078+00:00, sha 5def245d6cea)
  - site_page: https://www.effect.website/docs/v3/additional-resources/myths (fetched 2026-08-29T08:04:18.186647+00:00, sha f42ddbdb6bca)
  - site_page: https://www.effect.website/docs/v3/additional-resources/effect-vs-fp-ts (fetched 2026-08-29T08:04:18.188511+00:00, sha 738d102b02b6)
  - site_page: https://www.effect.website/docs/v3/additional-resources/effect-vs-neverthrow (fetched 2026-08-29T08:04:18.190989+00:00, sha 888214c9e0f5)
  - site_page: https://www.effect.website/docs (fetched 2026-08-29T08:04:18.194552+00:00, sha 995def3abf9a)
  - site_page: https://www.effect.website/docs/v3/api (fetched 2026-08-29T08:04:18.196847+00:00, sha 013ce9e2d91c)
  - site_page: https://www.effect.website/blog/releases/effect/40-rc (fetched 2026-08-29T08:04:18.184857+00:00, sha 3331a3663ccc)
- Data as of 2026-08-30T08:39:29.467469+00:00.