jmdict-go is a simple library written in Go for parsing the raw data files for the JMDict (vocabulary) JMnedict (names), and KANJIDIC (Kanji) dictionaries. As far as I know, these are the only publicly available Japanese dictionaries and are therefore used by a variety of tools including Yomitan-Import.
The XML format used to store dictionary entries and entity data was deceptively annoying to work with, leading to the creation of this library. Please see the documentation page for a technical overview of how to use this library.