5 releases

Uses new Rust 2021

1.0.0-beta.5 Apr 5, 2022
1.0.0-beta.4 Mar 9, 2022
1.0.0-beta.3 Feb 16, 2022
1.0.0-beta.2 Jan 22, 2022
1.0.0-beta.1 Jan 19, 2022

#420 in Game dev

Download history 158/week @ 2022-06-14 195/week @ 2022-06-21 257/week @ 2022-06-28 163/week @ 2022-07-05 352/week @ 2022-07-12 279/week @ 2022-07-19 462/week @ 2022-07-26 312/week @ 2022-08-02 411/week @ 2022-08-09 521/week @ 2022-08-16 563/week @ 2022-08-23 500/week @ 2022-08-30 357/week @ 2022-09-06 570/week @ 2022-09-13 520/week @ 2022-09-20 771/week @ 2022-09-27

2,239 downloads per month
Used in launchdarkly-server-sdk



LaunchDarkly Rust SDK Evaluation Engine

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This version of the evaluation engine is a beta version and should not be considered ready for production use while this message is visible.

LaunchDarkly overview

LaunchDarkly is a feature management platform that serves over 100 billion feature flags daily to help teams build better software, faster. Get started using LaunchDarkly today!

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Getting started

This repository contains the internal feature flag evaluation logic and data model used by the LaunchDarkly Rust SDK. It is packaged separately because it is also used by internal LaunchDarkly components. Applications using the LaunchDarkly Rust SDK should not need to reference this package directly.

Learn more

Check out our documentation for in-depth instructions on configuring and using LaunchDarkly. You can also head straight to the complete reference guide for the Rust SDK, or the generated API documentation for this project.


We encourage pull requests and other contributions from the community. Check out our contributing guidelines for instructions on how to contribute to this SDK.

About LaunchDarkly

  • LaunchDarkly is a continuous delivery platform that provides feature flags as a service and allows developers to iterate quickly and safely. We allow you to easily flag your features and manage them from the LaunchDarkly dashboard. With LaunchDarkly, you can:
    • Roll out a new feature to a subset of your users (like a group of users who opt-in to a beta tester group), gathering feedback and bug reports from real-world use cases.
    • Gradually roll out a feature to an increasing percentage of users, and track the effect that the feature has on key metrics (for instance, how likely is a user to complete a purchase if they have feature A versus feature B?).
    • Turn off a feature that you realize is causing performance problems in production, without needing to re-deploy, or even restart the application with a changed configuration file.
    • Grant access to certain features based on user attributes, like payment plan (eg: users on the ‘gold’ plan get access to more features than users in the ‘silver’ plan). Disable parts of your application to facilitate maintenance, without taking everything offline.
  • LaunchDarkly provides feature flag SDKs for a wide variety of languages and technologies. Check out our documentation for a complete list.
  • Explore LaunchDarkly


~96K SLoC