Sources
JMdict
This site uses the JMdict dictionary file. It is the property of the Electronic Dictionary Research and Development Group, and is used in conformance with the Group's licence. Licence: CC BY-SA 4.0. Source: JMdict_e.gz.
JLPT levels
JLPT data comes from Jonathan Waller's JLPT Resources page (Creative Commons BY), matched to JMdict entries by yomitan-jlpt-vocab (CC BY-SA 4.0). There are no official JLPT word lists; these levels are a well-tested guide.