Translating high-speed electrical signals to the optical domain, electro-optic (EO) modulators are key components of photonic systems. On a technological level, lithium niobate (LN) has become a mainstay for such devices, offering a unique combination of strong EO activity and chemical stability as well as wide-band transparency and the ability to withstand high optical power levels. Recent advances in thin-film LN have opened an attractive path towards compact footprint, low operation voltage and large bandwidth, while maintaining the intrinsic advantages of the underlying material system. However, there is still a need to further reduce the component size and increase the component density of LN circuits to truly enable large scale photonic integration in volume over the current wafer sizes, which are still far from the 200-300 mm scale of silicon photonics. It is thus the goal of HDLN to establish an internationally unique technology base related to high-density thin-film LN technology. HDLN will demonstrate the viability of the technology platform through a series of demonstrators, geared towards highly relevant applications such as ultra-fast optical communications and ultra-wideband photonic-electronic signal processing. HDLN brings together a careful selection of experienced partners from academia and industry, comprising a recently incorporated start-up for the manufacturing platform, an independent photonic design and test house, and an internationally leading company in the field of communications that validates the technology at the application level.