Java Generator
Commercial use OK
380+ models
No watermark
No sign-up needed
Model:
+ GPT-5, Claude, Gemini
Describe what you need and get production-ready Java 21 with records, sealed classes, pattern matching, and javadoc. Self-hosted Qwen 3 Coder handles standard CRUD / Spring Boot / concurrency for free under the daily pool; premium Claude Sonnet / GPT-5 nail complex generics and long multi-class refactors better than GitHub Copilot.
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Generate Java code with free AI. Classes, methods, and complete programs.
How to Use Java Generator
1
Enter your input
Type text, upload a file, or describe what you want. No account needed.
2
Click generate
Our AI processes your request in seconds using the best open-source models.
3
Download & share
Download, copy, or share your result. Free for personal and commercial use.
Use this tool via API
Automate this tool from your own code. OpenAI-compatible REST endpoint, Bearer-token auth, no extra SDK required. Token costs match the web interface.
curl -X POST https://api.free.ai/v1/chat/ \
-H "Authorization: Bearer sk-free-..." \
-H "Content-Type: application/json" \
-d '{"model": "qwen-coder", "messages": [{"role": "user", "content": "Write a Python function that reverses a string."}]}'Java Generator — FAQ
Modern idiomatic Java targeting Java 21 (LTS) by default — includes records, sealed classes, pattern-matching switch, virtual threads, text blocks, structured concurrency. Downgrade to Java 17, 11, or 8 via the target picker. Every output compiles as-is with the imports, package declaration, and Maven/Gradle coordinates named in a comment when external libs are used. 8 style presets (Production / Spring Boot / Concurrent / Streams / Classic OOP / Android SDK / Jakarta EE / JUnit test).
Yes — a medium-sized class generation costs ~1,500 tokens on the default Qwen 3 Coder model, comfortably inside the 2,500 anonymous or 10,000 signed-up daily pool. Premium Claude Sonnet / GPT-5 available per-generation for complex multi-class Spring Boot answers where the free model occasionally misses a constraint.
Copilot ($10-19/mo) is an IDE plugin that autocompletes as you type — tightly integrated but requires subscription. Cursor ($20/mo) is a full IDE. CodeWhisperer is AWS-focused, free for individuals. Our tool is a web generator for when you are prototyping, in a code-review context, or want a one-shot production-quality class without installing anything. Pair us with Copilot — we write the scaffolding, Copilot fills in the loops.
Java 21 (the current LTS) for new projects — you get virtual threads, pattern matching, records, sealed classes. Java 17 for projects already on 17 (also LTS, widely supported). Java 11 if your deployment is locked to an older container. Avoid Java 8 unless maintaining legacy code — most modern idioms do not exist there and Oracle commercial updates ended in 2022 for non-paying users.
Yes — set style to "Spring Boot" and depth to "Multi-file" (4/4). The output uses `// === src/main/java/.../Name.java ===` headers to separate files. Includes @RestController, @Service, @Repository layers, @Valid input DTOs, @ControllerAdvice global error handling, and constructor injection. Jackson serialization is handled automatically with records as DTOs. Spring Boot 3.x (jakarta.* imports) is emitted when target >= 17.
Yes — pick "Android SDK" style. Output uses Activity / Fragment / ViewModel lifecycle patterns, LiveData or StateFlow for observables, Retrofit for network. Coroutines are preferred when Kotlin interop is detected — Java Generator will suggest switching to our Kotlin generator for fully-idiomatic Android. Never blocks the main thread.
Qwen 3 Coder handles typical bounded generics well (`<T extends Comparable<T>>`, wildcards, PECS). For very complex higher-kinded generics, recursive types, or heavy reflection trickery, switch to Claude Sonnet or GPT-5 in the premium group — their multi-step reasoning catches edge cases the free model misses.
Yes — both are toggles above the Generate button. Javadoc defaults to ON for production style (every public method gets @param / @return / @throws). Tests are off by default; turn them on to get a JUnit 5 + Mockito test class exercising the happy path and one edge case.
Yes — switch to the "Paste starter / stub" tab and paste your class outline, method signatures, or partial implementation. The model completes your structure faithfully without renaming things or rearranging your package.
For Jakarta EE / Spring Boot 3 (target Java >= 17) we emit `jakarta.*` imports. For Spring Boot 2.x paths or legacy Java 11 we emit `javax.*`. Pick your target carefully — mixing the two causes compile errors Spring Boot users hit often.
Review every output before deploying, same as you would a junior developer’s pull request. The code is usually correct and follows Oracle conventions, but the model does not have your runtime constraints, security model, or full codebase context. For security-sensitive code run our /code/security/ audit on the output, and for refactors use /code/review/.
Yes — POST to /v1/chat/ with the same system prompt this page builds. Good for code-generation automation in CI/CD pipelines or IDE plugins. Bearer auth, rate-limited. Docs at /api/.
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