server SDK

Java feature flags

The Java SDK docs publish Maven and Gradle coordinates for io.featureflow:featureflow-java-sdk version 1.4.2. Build one FeatureflowClient and reuse it. In Spring, declare it as a @Bean. The key is a server environment key, sdk-srv-env-….

Java docs · GitHub · io.featureflow:featureflow-java-sdk

Set it up with your coding agent

Paste this into Claude Code, Cursor or any coding agent. It installs the Java SDK, creates the client and evaluates your first flag.

Or set it up by hand

Install

<dependency>
  <groupId>io.featureflow</groupId>
  <artifactId>featureflow-java-sdk</artifactId>
  <version>1.4.2</version>
</dependency>

implementation 'io.featureflow:featureflow-java-sdk:1.4.2'

Initialise

String apiKey = "sdk-srv-env-YOUR_API_KEY";
FeatureflowClient featureflow = FeatureflowClient.builder(apiKey).build();

Evaluate a flag

FeatureflowUser user = new FeatureflowUser("unique-user-id")
    .withAttribute("tier", "silver")
    .withStringAttributes("user_role", Arrays.asList("admin", "beta_tester"));

if (featureflow.evaluate("my-feature-key", user).isOn()) {
    // enabled
}

Kill switch

Branch on evaluate("my-feature-key", user).isOn() or isOff(). Register known features with withFeatures if you want them in the dashboard before anyone flips them. withUpdateCallback runs when a control changes.

The operational side is the kill switch. Turning the flag off does not require a redeploy.

Gradual rollout

Percentage rollouts are configured on the flag. Pass a stable user id so the same person stays in the same bucket. evaluate(key, user).is(value) matches a named variant. value() returns the variant key.

See progressive rollout for the dashboard control. Release pipelines and approval workflows, if the change itself needs a review, are on the Business plan at $399 a month. That price is on the pricing page.

Targeting

withAttribute accepts String, Number, boolean or DateTime. withStringAttributes, withNumberAttributes and withDateAttributes accept a list, and a rule may match any value in the list. withUserProvider supplies the current user in Spring. Set saveUser(false) on the user if you do not want attributes stored. jsonValue() needs version 1.3.1 or later and returns a Gson JsonElement, or null.

Frequently asked questions

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