"Summer Days" is a song by Dutch DJ and record producer Martin Garrix, featuring American rapper Macklemore and singer Patrick Stump of Fall Out Boy. The song was released on 25 April 2019. The music video for the song was released on 22 May 2019.
On 20 April 2019, Garrix, Macklemore and Stump all simultaneously shared a picture with the caption "I got this feeling on a Summer day" on their social media. The collaboration was officially confirmed by Garrix two days later. Garrix teased the release by posting a snippet of the song. Kat Bein of Billboard described the collaboration as "a cross-genre-sing-along".