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  • 🎉 Welcome the new oatpp version 1.3.0. Now it's better than ever! See the changelog for details. 🎉

Oat++ is a modern Web Framework for C++. It's fully loaded and contains all necessary components for effective production level development. It's also light and has a small memory footprint.



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Quick Overview


Build Powerful API And Document It With Swagger-UI

See ApiController for more details.

  info->summary = "Get one User by userId";

  info->addResponse<Object<UserDto>>(Status::CODE_200, "application/json");
  info->addResponse<Object<StatusDto>>(Status::CODE_404, "application/json");
  info->addResponse<Object<StatusDto>>(Status::CODE_500, "application/json");

  info->pathParams["userId"].description = "User Identifier";
ENDPOINT("GET", "users/{userId}", getUserById,
         PATH(Int32, userId))
  return createDtoResponse(Status::CODE_200, m_userService.getUserById(userId));

Access Databases And Keep Your Data Consistent

See Oat++ ORM for more details.

      "INSERT INTO users (username, email, role) VALUES (:username, :email, :role);",
      PARAM(oatpp::String, username), 
      PARAM(oatpp::String, email), 
      PARAM(oatpp::Enum<UserRoles>::AsString, role))

Frequently Asked Questions

Q: "Oat++" name?

  • "Oat" is something light, organic, and green. It can be easily cooked and consumed with no effort.
  • "++" gives a hint that it is "something" for C++.

Q: What is the main area of Oat++ application?

Oat++ is used for many different purposes, from building REST APIs that run on embedded devices to building microservices and highly-loaded cloud applications.

But the majority of use cases appears to be in IoT and Robotics.

Q: How portable is Oat++?

Theoretically, Oat++ can be easily ported everywhere where you have threads and network stack. With an additional comparably small effort, it can be ported almost everywhere depending on how much you strip it and what would be the final binary size.

See supported platforms for additional info.

Q: What is the size of a minimal Oat++ application?

About 1Mb, depending on C/C++ std-lib and oatpp version.

Q: Which Oat++ API to choose, Simple or Async?

Always choose Simple API wherever possible. Simple API is more developed and makes the code cleaner.

Async API is designed for small, specific tasks that run at high concurrency levels ex.:

  • Serving file downloads to a large number of concurrent users (1K users and more).
  • Streaming to a large number of clients (1K or more).
  • Websocket Chat servers.

For all other purposes use simple API.



  • REST Service - A complete example of a "CRUD" service (UserService) built with Oat++. REST + Swagger-UI + SQLite.
  • REST Client - Example project of how-to use Retrofit-like client wrapper (ApiClient) and how it works.


  • Can Chat - Feature-complete rooms-based chat for tens of thousands users. Client plus Server.
  • WebSocket - Collection of oatpp WebSocket examples.
  • YUV Websocket Stream - Example project how-to create a YUV image stream from a V4L device (i.E. Webcam) using websockets.


  • SQLite - A complete example of a "CRUD" service. REST + Swagger-UI + SQLite.
  • PostgreSQL - Example of a production-grade entity service storing information in PostgreSQL. With Swagger-UI and configuration profiles.
  • MongoDB - Example project how to work with MongoDB using oatpp-mongo mondule. Project is a web-service with basic CRUD and Swagger-UI.


  • Example-IoT-Hue - Example project how-to create an Philips Hue compatible REST-API that is discovered and controllable by Hue compatible Smart-Home devices like Amazon Alexa or Google Echo.


  • HTTP Live Streaming Server - Example project on how to build an HLS-streaming server using Oat++ asynchronous API.
  • YUV Websocket Stream - Example project how-to create a YUV image stream from a V4L device (i.E. Webcam) using websockets.


  • TLS With Libressl - Example project how-to setup secure connection and serve via HTTPS.


Asynchronous API

  • Async Service - Example project on how to use asynchronous API to handle a large number of simultaneous connections.

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