We introduce the MetaMIDI Dataset (MMD), a large scale collection of 436,631 MIDI files and metadata. MMD, contains artist and title metadata for 221,504 MIDI files, and genre metadata for 143,868 MIDI files, collected during the web-scraping process. MIDI files in MMD, were matched against a collection of 32,000,000 30-second audio clips retrieved from Spotify, resulting in over 10,796,557 audio-MIDI matches. In addition, we linked 600,142 Spotify tracks with 1,094,901 MusicBrainz recordings to produce a set of 168,032 MIDI files that are matched to the MusicBrainz database. We also provide a set of 53,496 MIDI files using audio-MIDI matches where the derived metadata on Spotify is a fuzzy match to the web-scraped metadata. These links augment many files in the dataset with the extensive metadata available via the Spotify API and the MusicBrainz database. We anticipate that this collection of data will be of great use to MIR researchers addressing a variety of research topics.