# What is OpenHarmony (OHOS)? A clear explanation

> OpenHarmony (OHOS) is an open-source, multi-device operating system governed by the OpenAtom Foundation. Learn its device classes, kernels, ArkTS/ArkUI and version history.

Source: https://ohosify.com/en/blog/what-is-openharmony
Published: 2026-10-01
Updated: 2026-10-01

**Short answer:** OpenHarmony (OHOS) is an open-source operating system governed by the OpenAtom Foundation. It is designed to run on many device types, from tiny microcontrollers to phones and tablets, using a single application framework (ArkUI) and a preferred language called ArkTS.

## What is OpenHarmony?

OpenHarmony is an open-source project that provides the base of a distributed, multi-device operating system. Huawei donated the original source code to the OpenAtom Foundation, which now governs it. The first release, OpenHarmony 1.0, appeared on September 10, 2020.

OpenHarmony is not the same thing as HarmonyOS, which is Huawei's commercial operating system built on top of it. See [OpenHarmony vs HarmonyOS](/en/blog/openharmony-vs-harmonyos) for the differences.

## What device classes does OpenHarmony support?

OpenHarmony defines three system types, based on how much memory and processing power a device has:

| System type | Typical hardware | Minimum RAM (as documented) |
|---|---|---|
| Mini system | ARM Cortex-M, 32-bit RISC-V microcontrollers | 128 KB |
| Small system | ARM Cortex-A application processors | 1 MB |
| Standard system | ARM Cortex-A with a GPU (phones, tablets, smart screens) | 128 MB |

## Which kernels does OpenHarmony use?

OpenHarmony is kernel-agnostic. A Kernel Abstraction Layer lets a device use LiteOS (in two variants, for small and mini systems), the Linux kernel for larger devices, or the UniProton real-time OS. Device makers pick the kernel that fits the hardware.

## How do you develop apps for OpenHarmony?

Apps are written in **ArkTS** (preferred), JavaScript, C and C++. User interfaces use **ArkUI**, a declarative UI framework. The official IDE is DevEco Studio. A minimal ArkUI page looks like this:

```ts
@Entry
@Component
struct Index {
  @State message: string = 'Hello World';

  build() {
    Column() {
      Text(this.message)
        .fontSize(50)
        .fontWeight(FontWeight.Bold)
    }
    .width('100%')
  }
}
```

Learn more in [What is ArkTS?](/en/blog/what-is-arkts), [How to install DevEco Studio](/en/blog/install-deveco-studio) and [Your first ArkTS app](/en/blog/first-arkts-app).

## What are the OpenHarmony versions?

Each OpenHarmony release has a matching API level. Selected releases:

| Version | Release date | API level |
|---|---|---|
| 1.0 | Sep 10, 2020 | 5 |
| 3.2 (LTS) | Sep 21, 2022 | 8–9 |
| 4.1 | Mar 30, 2024 | 11 |
| 5.0.0 | Sep 29, 2024 | 12 |
| 5.1.0 | May 4, 2025 | 18 |
| 6.0 | Sep 7, 2025 | 20 |
| 6.1 | Mar 9, 2026 | 23 |

Source: the version history on [Wikipedia](https://en.wikipedia.org/wiki/OpenHarmony). Always confirm API levels in the official release notes before targeting a version.

## Where can you find the source code and documentation?

- Source code: [gitee.com/openharmony](https://gitee.com/openharmony)
- Documentation repository: [github.com/openharmony/docs](https://github.com/openharmony/docs)

## Next steps

- [OpenHarmony vs HarmonyOS](/en/blog/openharmony-vs-harmonyos)
- [How to install DevEco Studio](/en/blog/install-deveco-studio)
- [What is ArkTS?](/en/blog/what-is-arkts)