OpenTRNG initiative introduces an open-source framework for physical True Random Number Generators (TRNG), focusing on ring-oscillator-based architectures. This project offers a comprehensive toolkit comprising reference designs, emulation tools, and analytical tools aiming at facilitating the development and characterization of hardware TRNG implementations. Key components include emulators capable of simulating noisy ring oscillators and digital noise sources, hardware descriptions for FPGA implementations, and analytical tools for assessing randomness metrics such as variance, entropy and autocorrelation. By providing accessible resources and fostering collaboration within the community, OpenTRNG aims to accelerate the advancement and validation of TRNG architectures at different technology nodes and at the highest level of security. It also seeks to promote good design practices, methodology, and reproducibility in the field of random number generation.