zio / zio   2.0.22

Apache License 2.0 Website GitHub

ZIO — A type-safe, composable library for async and concurrent programming in Scala

Scala versions: 3.x 2.13 2.12 2.11
Scala.js versions: 1.x 0.6
Scala Native versions: 0.4

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Welcome to ZIO

ZIO is a zero-dependency Scala library for asynchronous and concurrent programming.

Powered by highly-scalable, non-blocking fibers that never waste or leak resources, ZIO lets you build scalable, resilient, and reactive applications that meet the needs of your business.

  • High-performance. Build scalable applications with 100x the performance of Scala's Future.
  • Type-safe. Use the full power of the Scala compiler to catch bugs at compile time.
  • Concurrent. Easily build concurrent apps without deadlocks, race conditions, or complexity.
  • Asynchronous. Write sequential code that looks the same whether it's asynchronous or synchronous.
  • Resource-safe. Build apps that never leak resources (including threads!), even when they fail.
  • Testable. Inject test services into your app for fast, deterministic, and type-safe testing.
  • Resilient. Build apps that never lose errors, and which respond to failure locally and flexibly.
  • Functional. Rapidly compose solutions to complex problems from simple building blocks.

To learn more about ZIO, see the following references:


Following is a partial list of companies happily using ZIO in production to craft concurrent applications.

Want to see your company here? Submit a PR!



Ziverge is a leading contributor to ZIO.


Scalac sponsors ZIO Hackathons and contributes work to multiple projects in ZIO ecosystem.

Septimal Mind

Septimal Mind sponsors work on ZIO Tracing and continuous maintenance.


YourKit generously provides use of their monitoring and profiling tools to maximize the performance of ZIO applications.

Code of Conduct

See the Code of Conduct


Come chat with us on Badge-Discord.


Copyright 2017 - 2024 John A. De Goes and the ZIO Contributors. All rights reserved.