# Apache NuttX vs Zephyr RTOS

**Leader by Vioscale score:** Zephyr RTOS

| Attribute | Apache NuttX | Zephyr RTOS |
|---|---|---|
| **Vioscale score** | 42.1 (11% (low)) | 52.8 (40% (low)) |
| activity.commits_last_30d | 100 | 100 |
| adoption.dependent_repos | 0 | 0 |
| adoption.github_stars | 4,010 | 16,315 |
| deployment.options | `{"self_hosted":true}` | `{"self_hosted":true}` |
| description.long | An embedded operating system for microcontrollers ranging from 8-bit to 64-bit architectures, built on POSIX and ANSI standards with additional Unix-compatible APIs. | Zephyr is a real-time operating system optimized for resource-constrained embedded devices, ranging from simple sensors to sophisticated IoT devices and gateways. It provides a small-footprint kernel supporting multiple processor architectures and is built with security and long-product-lifecycle support as core design principles. |
| features.capabilities | - | `{"open_source":true,"target_class":"both"}` |
| integrations.count | - | 1 |
| integrations.list | - | `[{"name":"PlatformIO"}]` |
| language.primary | C | C |
| license.spdx | Apache-2.0 | Apache-2.0 |
| market.availability | - | `{"primaryMarkets":[],"availabilityScope":"global","availableCountries":[],"notAvailableCountries":[]}` |
| pricing | `{"type":"open_source","sourceUrl":"https://nuttx.apache.org","retrievedAt":"2026-08-20T16:36:12.280Z"}` | `{"type":"open_source","freeTier":true,"sourceUrl":"https://zephyrproject.org","retrievedAt":"2026-08-21T13:40:59.448Z"}` |
| pricing.free_tier | - | yes |
| pricing.model | open_source | commercial |
| pricing.price_level | free | free |
| pricing.transparent | - | yes |
| release.cadence_days | - | 6 |
| release.history | - | `[{"url":"https://github.com/zephyrproject-rtos/zephyr/releases/tag/v4.4.2","date":"2026-08-07T15:36:32Z","type":"stable","version":"v4.4.2"},{"url":"https://github.com/zephyrproject-rtos/zephyr/releases/tag/v3.7.3-rc1","date":"2026-08-06T00:38:42Z","type":"prerelease","version":"v3.7.3-rc1"},{"url":"https://github.com/zephyrproject-rtos/zephyr/releases/tag/v4.4.2-rc1","date":"2026-07-29T20:54:38Z","type":"prerelease","version":"v4.4.2-rc1"},{"url":"https://github.com/zephyrproject-rtos/zephyr/releases/tag/v4.3.1","date":"2026-06-23T12:27:28Z","type":"stable","version":"v4.3.1"},{"url":"https://github.com/zephyrproject-rtos/zephyr/releases/tag/v4.3.1-rc1","date":"2026-06-13T07:08:30Z","type":"prerelease","version":"v4.3.1-rc1"},{"url":"https://github.com/zephyrproject-rtos/zephyr/releases/tag/v4.4.1","date":"2026-06-10T18:06:45Z","type":"stable","version":"v4.4.1"},{"url":"https://github.com/zephyrproject-rtos/zephyr/releases/tag/v4.4.1-rc1","date":"2026-06-03T21:23:41Z","type":"prerelease","version":"v4.4.1-rc1"},{"url":"https://github.com/zephyrproject-rtos/zephyr/releases/tag/v4.4.0","date":"2026-04-14T21:33:16Z","type":"stable","version":"v4.4.0"},{"url":"https://github.com/zephyrproject-rtos/zephyr/releases/tag/v4.4.0-rc3","date":"2026-04-08T20:33:53Z","type":"prerelease","version":"v4.4.0-rc3"},{"url":"https://github.com/zephyrproject-rtos/zephyr/releases/tag/v4.4.0-rc2","date":"2026-04-02T21:06:28Z","type":"prerelease","version":"v4.4.0-rc2"},{"url":"https://github.com/zephyrproject-rtos/zephyr/releases/tag/v3.7.2","date":"2026-03-31T19:09:36Z","type":"stable","version":"v3.7.2"},{"url":"https://github.com/zephyrproject-rtos/zephyr/releases/tag/v4.4.0-rc1","date":"2026-03-24T23:16:10Z","type":"prerelease","version":"v4.4.0-rc1"},{"url":"https://github.com/zephyrproject-rtos/zephyr/releases/tag/v4.2.2","date":"2026-03-23T16:05:02Z","type":"stable","version":"v4.2.2"},{"url":"https://github.com/zephyrproject-rtos/zephyr/releases/tag/v3.7.2-rc2","date":"2026-03-14T12:19:10Z","type":"prerelease","version":"v3.7.2-rc2"},{"url":"https://github.com/zephyrproject-rtos/zephyr/releases/tag/v4.3.0","date":"2025-11-13T19:56:12Z","type":"stable","version":"v4.3.0"},{"url":"https://github.com/zephyrproject-rtos/zephyr/releases/tag/v4.3.0-rc3","date":"2025-11-08T14:43:55Z","type":"prerelease","version":"v4.3.0-rc3"},{"url":"https://github.com/zephyrproject-rtos/zephyr/releases/tag/v4.3.0-rc2","date":"2025-11-01T14:49:19Z","type":"prerelease","version":"v4.3.0-rc2"},{"url":"https://github.com/zephyrproject-rtos/zephyr/releases/tag/v4.3.0-rc1","date":"2025-10-25T14:38:11Z","type":"prerelease","version":"v4.3.0-rc1"},{"url":"https://github.com/zephyrproject-rtos/zephyr/releases/tag/v4.2.1","date":"2025-10-07T22:55:23Z","type":"stable","version":"v4.2.1"},{"url":"https://github.com/zephyrproject-rtos/zephyr/releases/tag/v4.2.0","date":"2025-07-19T01:11:16Z","type":"stable","version":"v4.2.0"}]` |
| security.scorecard | - | 7.1 |
| security.vulnerabilities | `{"count":0,"source":"https://advisories.ecosyste.ms/api/v1/advisories?ecosystem=pypi&package_name=pynuttx&per_page=100","last_12m":0,"max_severity":null}` | `{"count":0,"source":"https://advisories.ecosyste.ms/api/v1/advisories?ecosystem=go&package_name=github.com%2Fzephyrproject-RTOS%2Fzephyr&per_page=100","last_12m":0,"max_severity":null}` |

## Capabilities (Embedded IOT Dev)

| Capability | Apache NuttX | Zephyr RTOS |
|---|:--:|:--:|
| **Capabilities** |  |  |
| Target class | - | Both |
| Rtos type | - | - |
| Low power support | - | - |
| Tls dtls stack | - | - |
| Ota updates | - | - |
| Device management console | - | - |
| Device provisioning | - | - |
| Open source | - | ✓ |
| PSA certified | - | - |
| Rust support | - | - |

*Source: Vioscale. Generated 2026-09-01T16:44:20.408Z. "-" = undocumented, not absent.*