Kora Playground

The hands-on playground for the Kora framework.
Clone it, run any module, poke at real endpoints, break things, and see how Kora works — in Java and Kotlin.

Framework · Documentation · Getting Started · Kora Skills

Русская версия: README.ru.md

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This is the sandbox for the Kora framework. Every module here is a small, self-contained service that runs one part of Kora end to end — real code, real config, real tests. There is nothing to wire up: check out the repo, start a module, send it a request, then open the source and change something to see what happens.

Everything comes in both Java and Kotlin, so you can play in whichever language you ship.

Even better with an AI agent. Install our kora-skills skill and let your AI agent run these examples, explain what Kora generated, and modify them with you — straight from the official guides and code.

Play with it in a minute

git clone https://github.com/kora-projects/kora-examples.git
cd kora-examples

# start any module — e.g. the HTTP server
./gradlew :kora-java-http-server:run

Then hit it, change a handler, and re-run:

curl http://localhost:8080/hello

Each example is an independent Gradle module, so you can also just build or test one in isolation:

./gradlew :kora-java-http-server:build     # build one module
./gradlew :kora-java-http-server:test      # run its tests
./gradlew build                            # build everything

Modules that need infrastructure (PostgreSQL, Kafka, Cassandra, S3, …) ship a docker-compose.yml and a Dockerfile next to their code — bring the dependencies up with docker compose up inside the module first. Every module has its own README.md with the exact commands, ports, and example requests.

Requires JDK 17+; the Gradle wrapper (./gradlew) is included, so nothing else to install.

What to try first

• Hello World — the smallest Kora service.
• Getting Started app — the guided first service.
• Dependency Injection intro — how the compile-time graph is wired.
• Full CRUD service — HTTP + JDBC + tests together, closest to a real app.
• Run ./gradlew :<module>:test on any module and open build/generated/… to read the code Kora generated for it.

Two folders

• examples/ — standalone demonstration services, one per Kora module. Reach for these to play with a single feature in isolation.
• guides/ — companion apps for the step-by-step documentation guides: read the guide, run its app, follow along.

What you can play with

Each row links the same runnable service in both languages.

Getting started & core

Topic	Java	Kotlin
Hello World	Java	Kotlin
Full CRUD service	Java	Kotlin
CRUD with @KoraSubmodule	Java	Kotlin
Config — HOCON	Java	Kotlin
Config — YAML	Java	Kotlin

HTTP & API

Topic	Java	Kotlin
HTTP server	Java	Kotlin
HTTP client	Java	Kotlin
OpenAPI → HTTP server	Java	Kotlin
OpenAPI → HTTP client	Java	Kotlin
SOAP client	Java	Kotlin

Databases

Topic	Java	Kotlin
JDBC	Java	Kotlin
R2DBC	Java	Kotlin
Vert.x	Java	Kotlin
Cassandra	Java	Kotlin

Messaging & RPC

Topic	Java	Kotlin
Kafka	Java	Kotlin
gRPC server	Java	Kotlin
gRPC client	Java	Kotlin
S3 — AWS SDK	Java	Kotlin
S3 — MinIO	Java	Kotlin

Resilience & aspects

Topic	Java	Kotlin
Resilience (@Retry, @Timeout, @CircuitBreaker, @Fallback)	Java	Kotlin
Cache — Caffeine	Java	Kotlin
Cache — Redis	Java	Kotlin
Validation	Java	Kotlin
Scheduling — JDK	Java	Kotlin
Scheduling — Quartz	Java	Kotlin

Observability & workflow

Topic	Java	Kotlin
Telemetry (metrics, tracing, logs)	Java	Kotlin
Camunda 7 engine	Java	Kotlin
Camunda 8 Zeebe worker	Java	Kotlin

GraalVM Native Image

Ahead-of-time compiled native builds — see examples/graalvm:

CRUD · JDBC · CRUD · R2DBC · CRUD · Vert.x · CRUD · Cassandra · Kafka

Guides

The guides/ tree holds one companion app per documentation guide, in Java and Kotlin — from getting started and dependency injection to databases, HTTP, Kafka, gRPC, resilience, validation, observability, and the three testing styles (JUnit, integration, black-box). Read a guide in the docs and run its app side by side.

Documentation & community

• Documentation — kora-docs
• Guides — Getting Started
• Framework source — kora-projects/kora
• AI skill — kora-skills

License

Licensed under the Apache License 2.0.