Java rate-limiting library based on token-bucket algorithm.
Get dependency
The Bucket4j is distributed through Maven Central:
Java 17 dependency
<!-- For java 17+ -->
<dependency>
<groupId>com.bucket4j</groupId>
<artifactId>bucket4j_jdk17-core</artifactId>
<version>8.21.0</version>
</dependency>
Quick start
import io.github.bucket4j.Bucket;
...
// bucket with capacity 20 tokens and with refilling speed 1 token per each 6 second
private static Bucket bucket = Bucket.builder()
.addLimit(limit -> limit.capacity(20).refillGreedy(10, Duration.ofMinutes(1)))
.build();
private void doSomethingProtected() {
if (bucket.tryConsume(1)) {
doSomething();
} else {
throw new SomeRateLimitingException();
}
}
More examples can be found there
Bucket4j basic features
- Absolutely non-compromise precision - Bucket4j does not operate with floats or doubles, all calculation are performed in the integer arithmetic, this feature protects end users from calculation errors involved by rounding.
- Effective implementation in terms of concurrency:
- Bucket4j is good scalable for multi-threading case it by defaults uses lock-free implementation.
- In same time, library provides different concurrency strategies that can be chosen when default lock-free strategy is not desired.
- Effective API in terms of garbage collector footprint: Bucket4j API tries to use primitive types as much as it is possible in order to avoid boxing and other types of floating garbage.
- Pluggable listener API that allows to implement monitoring and logging.
- Rich diagnostic API that allows to investigate internal state.
- Rich configuration management - configuration of the bucket can be changed on fly
Bucket4j distributed features
In additional to basic features described above, Bucket4j provides ability to implement rate-limiting in cluster of JVMs:
- Bucket4j out of the box supports any GRID solution which compatible with JCache API (JSR 107) specification.
- Bucket4j provides the framework that allows to quickly build integration with your own persistent technology like RDMS or a key-value storage.
- For clustered usage scenarios Bucket4j supports asynchronous API that extremely matters when going to distribute world, because asynchronous API allows avoiding blocking your application threads each time when you need to execute Network request.
Bucket4j is not a framework, it is a library, with Bucket4j you need to write a code to achive your goals.
For generic use-cases, try to look at powerfull Spring Boot Starter for Bucket4j, that allows you to set access limits on your API effortlessly.
Its key advantage lies in the configuration via properties or yaml files, eliminating the need for manual code authoring.
Supported JCache compatible(or similar) back-ends
In addition to local in-memory buckets, the Bucket4j supports clustered usage scenario on top of following back-ends:
Redis back-ends
Valkey back-ends
Mongo back-ends
Memcached back-ends
| Back-end | Async supported | Documentation link |
|---|
Memcached/compare-and-swap based | Yes | bucket4j-memcached |
Cassandra back-ends
| Back-end | Async supported | Documentation link |
|---|
Apache Cassandra/Lightweight Transactions | Yes | bucket4j-cassandra |
JDBC back-ends
Local caches support
Sometimes you are having deal with bucket per key scenarios but distributed synchronization is unnecessary, for example where request stickiness is provided by a load balancer, or other use-cases where stickiness can be achieved by the application itself, for example, Kafka consumer. For such scenarios Bucket4j provides support for following list of local caching libraries:
Third-party integrations
Snapshot builds
Every commit/merge to the master branch is automatically built and published as a -SNAPSHOT artifact to GitHub Packages (see .github/workflows/snapshot-release.yml).
To consume a snapshot, add the GitHub Packages repository to your pom.xml:
<repositories>
<repository>
<id>github</id>
<name>Bucket4j GitHub Packages</name>
<url>https://maven.pkg.github.com/bucket4j/bucket4j</url>
</repository>
</repositories>
GitHub Packages requires authentication even for reading public packages, so add a server entry with your GitHub username and a personal access token that has the read:packages scope to your ~/.m2/settings.xml:
<servers>
<server>
<id>github</id>
<username>YOUR_GITHUB_USERNAME</username>
<password>YOUR_GITHUB_TOKEN</password>
</server>
</servers>
Then reference the snapshot version (current pom.xml version with the -SNAPSHOT suffix), for example:
<dependency>
<groupId>com.bucket4j</groupId>
<artifactId>bucket4j_jdk17-core</artifactId>
<version>8.22.0-SNAPSHOT</version>
</dependency>
Have a question?
Feel free to ask via:
License
Copyright 2015-2026 Vladimir Bukhtoyarov
Licensed under the Apache Software License, Version 2.0: http://www.apache.org/licenses/LICENSE-2.0.
