libnostr-c

A lightweight, portable C library for the Nostr protocol with native Lightning Network integration

What is libnostr-c?

A high-performance C implementation of the Nostr protocol built for efficiency and minimal dependencies. libnostr-c provides core event management, modern NIP-44 encryption powered by noscrypt, Lightning zaps, and WebSocket relay communication. Designed for embedded systems and Bitcoin/Lightning integrations with a focus on security and portability.

API Example

nostr_init();
nostr_keypair_generate();
nostr_event_create();
nostr_event_sign();
nostr_nip44_encrypt();
nostr_nip44_decrypt();
nostr_relay_connect();
... extended functions

Motivation

Building nostr applications in C requires reliable, efficient cryptographic operations and protocol handling. libnostr-c provides a complete implementation with modern NIP-44 encryption, Lightning integration, and minimal resource requirements. Built with security-first design principles and optimized for both desktop and embedded systems.

Platform Support

The following table lists supported platforms and cryptographic backends:

Platform	Crypto Backend	Notes	CI Status
Linux	noscrypt, secp256k1	GCC/Clang	✅ Tested
macOS	noscrypt, secp256k1	Clang	✅ Tested
Windows	noscrypt, secp256k1	MSVC	✅ Tested

Getting started

Please use the following links to obtain packages and extended documentation.

Documentation
Examples
Performance Analysis

Super quick start

Prerequisites:

• CMake 3.16+, C99 compiler, OpenSSL
• secp256k1, libcjson, libwebsockets (see BUILDING.md)

git clone https://github.com/privkeyio/libnostr-c.git
cd libnostr-c
mkdir build && cd build
cmake ..
make -j$(nproc)
sudo make install

For detailed installation instructions, dependency management, and platform-specific setup, see docs/BUILDING.md.

Notes

Builds

Automated builds and releases are available through GitHub Actions CI/CD.

Features

libnostr-c supports modular compilation - build only what you need:

• Core NIPs (01, 02, 13, 19, 57) enabled by default
• Optional NIPs (04, 17, 44, 47, 59) via feature flags
• Modern noscrypt backend provides NIP-44 encryption
• Fallback to secp256k1 for basic operations

License

The software in this repository is licensed under the GNU LGPL version 2.1 (or any later version). See the LICENSE file for details.

Acknowledgments

This project is powered by noscrypt for high-performance cryptographic operations and NIP-44 encryption.