Agentle4j

This docs was updated at: 2026-03-21

Java 25+, virtual-thread-friendly, Responses API-native

Type-safe agents, streaming, and structured output for Java

Get Started API Reference

---

✨ Key Features

• Agent Framework

  ---

  Complete agent system with tools, guardrails, memory, and handoffs

• Type-safe API

  ---

  Full OpenAI Responses API with Java records

• Real-time Streaming

  ---

  Virtual thread-based streaming with callbacks

• Structured Outputs

  ---

  Strongly-typed JSON responses

• Function Calling

  ---

  Auto-generated JSON schemas from Java classes

• OpenTelemetry

  ---

  Built-in observability with spans/metrics

---

⚙️ Runtime Model

• Agentle4j requires Java 25+ with preview features enabled.
• Core APIs are synchronous-first and designed to be used directly or dispatched onto virtual threads.
• Streaming is exposed through ResponseStream and AgentStream callbacks.
• The published artifact version documented here is 0.10.1.

---

🚀 Quick Example

import com.paragon.responses.Responder;
import com.paragon.responses.spec.CreateResponsePayload;
import com.paragon.responses.spec.Response;

// Create a responder
Responder responder = Responder.builder()
    .openRouter()
    .apiKey("your-api-key")
    .build();

// Build your request
var payload = CreateResponsePayload.builder()
    .model("openai/gpt-4o-mini")
    .addDeveloperMessage("You are a helpful assistant.")
    .addUserMessage("Hello!")
    .build();

// Get the response
Response response = responder.respond(payload);
System.out.println(response.outputText());

---

📦 Installation

MavenGradle

<dependency>
    <groupId>io.github.paragon-intelligence</groupId>
    <artifactId>agentle4j</artifactId>
    <version>0.10.1</version>
</dependency>

implementation 'io.github.paragon-intelligence:agentle4j:0.10.1'

Requires Java 25+ with preview features enabled.

---

📚 Documentation

Section	Description
Installation	Detailed setup instructions
Getting Started	Quick start guide
Agentic Patterns	Visual control-flow guide for agents, delegation, and orchestration
Guides	In-depth feature guides
API Reference	Auto-generated Javadoc
Examples	Code samples

---

🤝 Contributing

We welcome contributions! Please see our GitHub repository for more information.

---

Made with ❤️ by Paragon Intelligence