Goidelex is an openly accessible relational database in CSV format, linked by formal relationships. The launch version documents 695 headwords with extensive linguistic annotations, including orthographic forms using a normalised orthography, automatically generated phonemic transcriptions, and information about morphosyntactic features, such as gender, inflectional class, etc. Metadata in JSON format, following the Frictionless standard, provides detailed descriptions of the tables and dataset. The database is designed to be fully compatible with the Paralex and CLDF standards and is interoperable with existing lexical resources for Old Irish such as CorPH and DIL. It is suited to both qualitative and quantitative investigation into Old Irish morphology and lexicon, as well as to comparative research.