Swagger / springdoc alternative for Java

The Swagger alternative for Java that needs neither code changes nor a running app

OneAPI.app generates OpenAPI 3.0 documentation straight from your Java source via AST analysis. No @Operation annotations, no Spring coupling, no booting your services. Code is the documentation.

Get started Live demonpm install -g oneapi-cli

Terminal

$ oneapi analysis -p ./spring-boot-demo -o .
✅ OneAPI Schema parsed (8s): ./oneapi.json

$ oneapi openapi -s ./oneapi.json -o .
✅ openapi.json generated (OpenAPI 3.0)

$ oneapi service -s ./oneapi.json -r 'import request from "@/utils/request";' -o .
✅ Frontend services generated: ./services

Why developers switch

Zero integration cost

Drop-in replacement for Swagger and springdoc-openapi. You don't touch a line of business code and add zero annotations. Point OneAPI at your project and get docs.

Code is the documentation

Docs are derived directly from your Java source and Javadoc. What compiles is what gets documented — no drift, no separate spec to maintain.

Easy to extend

The same oneapi.json schema drives both backend OpenAPI output and frontend service code (TypeScript). Pipe it into UmiJS, Postman, or your own tooling.

How it works

01

Analyze

oneapi analysis parses your Java project (and decompiles JARs for third-party types) into oneapi.json.

oneapi analysis -p <project> -o <dir>

02

Generate OpenAPI

oneapi openapi emits an OpenAPI 3.0 file you can import anywhere.

oneapi openapi -s oneapi.json -o <dir>

03

Generate frontend services

oneapi service produces typed TypeScript service functions from the same schema.

oneapi service -s oneapi.json -r '<request import>' -o <dir>

Swagger annotations are technical debt

Every @Schema you add is code you must maintain, and every doc page depends on a running server. OneAPI removes both.

See the full comparison →

Frequently asked questions

Generate your first OpenAPI doc in minutes

Install the CLI and point it at any Spring Boot project — no annotations required.