picolibc/picolibc
Freepicolibc - a C library designed for embedded 32- and 64- bit systems.
FreeFree tier
About picolibc/picolibc
Picolibc is a C library offering standard C library APIs that targets small embedded systems with limited RAM. It was formed by blending code from Newlib and AVR Libc, providing a lightweight, BSD-licensed alternative for embedded development. The library supports a wide range of architectures including ARM, RISC-V, x86, MSP430, and many more, with integrated testing for many platforms. Picolibc is designed to be modular, supporting atomics for stdio ungetc and thread local storage. The code is almost entirely under BSD-like licenses, making it suitable for commercial embedded projects without GPL constraints.
Key Features
Standard C library APIs for embedded systems
Lightweight design targeting small RAM footprints
Blend of code from Newlib and AVR Libc
BSD-like license (no GPL restrictions)
Supports many architectures (ARM, RISC-V, x86, MSP430, etc.)
Integrated testing for most supported architectures
Atomic operations support for stdio ungetc
Modular with build system support (meson, cmake)
Pros & Cons
Pros
- BSD-like license enables use in proprietary projects without GPL obligations
- Wide architecture support including ARM, RISC-V, x86, MSP430, and more
- Built on well-established codebases (Newlib, AVR Libc) for reliability
- Active development with continuous integration testing
- Lightweight and suited for RAM-constrained devices
Cons
- Less mature ecosystem and community compared to Newlib or glibc
- Documentation primarily limited to the README and source comments
- Designed specifically for small embedded systems; not suitable for full-fledged OS environments
Best For
Embedded software development for microcontrollersIoT devices with limited memory resourcesReal-time systems requiring minimal C library overheadCross-platform embedded C library for various architecturesProjects that need a permissively licensed C library
FAQ
What is picolibc?
Picolibc is a C library that provides standard C library APIs for small embedded systems with limited RAM, formed by blending code from Newlib and AVR Libc.
What license does picolibc use?
Picolibc uses BSD-like licenses (2- and 3-clause BSD and other similar licenses). The GPL-related bits from Newlib have been removed. A few test files use GPL v2+ and one helper script uses AGPL v3+, but the library itself is permissively licensed.
Which architectures does picolibc support?
Picolibc supports many architectures including ARM (32- and 64-bit), RISC-V (32- and 64-bit), x86 (i386, x86_64), MSP430, AVR, ARC, LatticeMico32, LoongArch, MIPS, Nios II, OpenRisc, Power9, Renesas RX, SparcV8, SuperH, Xtensa (ESP32), and more. Some have integrated testing; others have build infrastructure.
Is picolibc free to use?
Yes, picolibc is open source and free to use. It is hosted on GitHub under a permissive BSD-like license.