Contiki-NG

Contiki-NG is a free, open-source operating system for resource-constrained IoT devices. It suits developers building low-power edge nodes on supported hardware and standard network protocols. Choose it for a compact, configurable footprint and a substantial documented stack; look elsewhere if CSMA link-layer security is essential.

Overview

With code on the order of 100 kB and memory configurable as low as 10 kB, Contiki-NG is aimed at devices where operating-system overhead is a practical constraint. That focus makes it a strong candidate for low-power IoT nodes, but not a general-purpose system for broader computing workloads.

Its resource-efficient IPv6 stack brings together TCP, UDP, DNS, RPL, CoAP, LWM2M and WebSockets, with IEEE 802.15.4 and TSCH beneath IPv6. MQTT integration is also documented. Together, these options give protocol-focused projects room to build without making a larger platform the default choice.

Key features

Networking and security

Documented modules include IPv6 multicast, RPL, CoAP and CoAPs, OMA LWM2M, TSCH/6TiSCH and SNMP. Security options include DTLS with Mbed TLS, secure CoAP, and pre-shared keys or certificates. EDHOC is supported for mutual authentication, forward secrecy and identity protection, making the stack a credible fit for deployments that need documented authentication and transport protections.

Link-layer protection has a narrower reach: security is supported for IEEE 802.15.4 TSCH, while CSMA link-layer security is planned. If a design depends on CSMA security now, that is a substantive reason to choose another operating system rather than assume equivalent coverage.

Development and simulation

Cooja native motes and a Renode tutorial provide documented simulation paths. The recommended Docker image offers a consistent development environment, while native toolchain installation is documented for Linux and macOS. These are useful options for teams that want repeatable setup or simulation alongside supported hardware work; MQTT guidance, including Mosquitto installation on Linux, covers a common integration path.

Pricing

Contiki-NG costs nothing. The plan is an open-source operating system under the 3-clause BSD license unless otherwise specified, so it suits teams that want to adopt and work with the system without a software plan charge. There is no free trial because the product is free. The license is a meaningful part of the decision: review it against the needs of the project and any components with different terms.

Platforms

Contiki-NG supports Linux, macOS, Windows and self-hosted deployment, with an edge deployment model. Documented hardware includes TI cc2538 and SimpleLink, Nordic nRF52840/nRF5340, Silicon Labs Gecko, OpenMote, Tmote Sky/TelosB and Zolertia Zoul boards. Supported device operating systems also include ARM Cortex-M3/M4, TI MSP430, TI CC13xx/CC26xx, Nordic nRF5340/nRF52840 and Silicon. Developers should match their target board and toolchain to the documented platforms before committing to a build.

Who it's for

Contiki-NG is best for embedded developers building low-power IoT devices with tight memory budgets and a need for standards-based networking. Its low configurable memory use, broad protocol coverage and simulation resources favor projects that can work within its documented hardware and development paths. It is a weaker fit when CSMA link-layer security is required, or when the goal is a general-purpose operating system rather than a constrained-device platform.

Pros and cons

Pros

Memory use can be configured as low as 10 kB, suiting severely constrained nodes.

The IPv6 stack and documented modules cover a wide range of IoT networking needs, from RPL and CoAP to TSCH/6TiSCH and SNMP.

DTLS, secure CoAP, key or certificate authentication, and EDHOC provide several documented security mechanisms.

Cooja, Renode guidance and a recommended Docker environment support simulation and more consistent development setup.

Free and open source under the 3-clause BSD license unless otherwise specified.

Cons

CSMA link-layer security is planned, not supported; projects that require it cannot rely on Contiki-NG for that capability.

The system is specifically designed for resource-constrained IoT devices, limiting its relevance to general-purpose workloads.

Development paths are tied to documented hardware and toolchains, so target compatibility needs to be established early.

Alternatives

IoT Operating Systems is a useful next stop if you want to compare more options in this category. Choose Apache Mynewt instead if you want a free embedded OS and development tools under the Apache License 2.0. Particle Device OS may suit teams that prefer a freemium option: its free plan allows 100 devices and 100K Data Operations per month, while Basic is $299 a month and scales in blocks of 100 devices.

Consider PX5 RTOS if a paid licensing model is a better match; its Device/Product Licensing plan is a 5000.00 USD one-time fee with perpetual licensing, full source code, no royalties and professional support. Micrium OS is another free option. Azure Sphere OS is paid and bundles a certified MCU with its OS license and security-service access. VxWorks offers a freemium model with a plan for up to 3 seats online. PikeOS is a paid alternative, while RT-Thread is free.

Verdict

Choose Contiki-NG for low-power IoT nodes where memory matters and its documented IPv6, IoT protocol and security stack fits the design. Its combination of configurable low resource use and broad networking coverage is the clearest reason to choose it. Look elsewhere when CSMA link-layer security is a requirement or your project needs a general-purpose system.