This article presents the research process of the project "The Ethnic Group Digital Archive Project: Promoting the protection and preservation of language and culture diversity in Thailand". This project involved the development of a local digital archive website for the ethnic groups of Thailand to archive, preserve, and transmit their knowledge of languages and cultures to their younger generations and those interested. The core objective of this digital archive development was the implementation of the archive website with uncomplicated accessibility and simple and interesting design that serves the language documentation purpose. The digital archive output includes collections from 18 ethnic groups in Thailand, containing 385 bundles of legacy and fieldwork data obtained by means of video, audio, text, image, and ELAN file. Despite the low number of researchers working on language documentation and archiving, the research team managed to expand both national and international networks working in this particular field of study. This serves as an opportunity for scholars and speaker communities in Thailand to recognize the importance of local knowledge preservation and transmission, and the availability of the digital archive is a practical way to support sustainable data preservation and accessibility in the future.