TypeScript library · Effect 4.x is LTS
Each digit of the version says what is allowed to break.
Effect is a library for building robust, type-safe, production-grade applications in TypeScript — typed errors, dependency injection, structured concurrency, scheduling, tracing and schema validation. Teams run it in systems they expect to keep for years, so the release contract is written down.
The stability contract
from the READMERead the label before the digit. An API’s tier decides which part of the version can break it — so you see the risk when you adopt an API, not when you upgrade.
Support, in years
durations are the project’s; positions are schematicThe project commits to durations, not dates. Where the next major lands is unknown, so the dashed line marks an anchor, not a calendar position.
The monorepo also ships AI provider packages — Anthropic, OpenAI, OpenRouter and any OpenAI-compatible API — and every package is released together with synchronized versions, so the integrations move on the same version numbers as the core.