Kaththi (soundtrack)

Anirudh composed the theme music four days after signing the film,[3] which was featured in the digital first look poster.[4] He later added that the album would feature two theme music versions.[5] In April 2014, two more songs were produced[6][7] after which Anirudh confirmed that 3 of the songs were completed.[8] The next month, Bollywood music director Vishal Dadlani sang a track for the film.[9] In August 2014, Andrea Jeremiah and singer Adhi of Hiphop Tamizha had each recorded a song.[10] Hiphop Tamizha said that he had used classic Tamil words in the song.[11] Keba Jeremiah played the guitar for one song which he labelled as "a soul stirring melody".[12][13] Lyricist Madhan Karky called one of the songs he wrote a "stylish folk number".[14] Vijay was reported to sing a "love kuththu" number.[15] In early September 2014, Vijay finished recording his song, titled "Selfie Pulla" and the team went to London to shoot its song sequence.[16] Anirudh confirmed on 14 September 2014 that K. J. Yesudas had recorded a song for the film.[17] A rough cut version of "Selfie Pulla" sung by Anirudh got leaked onto the internet.[18]

The audio rights were purchased by Eros Music.[19][lower-alpha 1] Initial reports that the album release would be held in mid-September 2014 at the Wembley Arena in London,[21] and that the lead pair would perform at the audio launch along with Anirudh proved to be untrue.[22] The audio launch of the movie was held on 24 September 2014, at The Leela Palace Hotel in Chennai.[2] Ma Ka Pa Anand along with VJ Priyanka, hosted the audio launch,[23] whilst composer Anirudh and Hiphop Tamizhan Adhi were part of stage performances.[24]

The track list was released on 21 September 2014 by Eros Music through their official Twitter account.[25] The full album was released through iTunes digitally on 23 September 2014, and in all streaming platforms the following day.

Durgesh Haridas of The Indian Express stated, "The OST is arguably the best for a Vijay movie in recent times and Anirudh’s variety and experimentation is helping him establishing himself as one of Kollywood’s top music makers."[26] K. Siddharth of Sify rated the album 3.5 out of 5, saying that "Anirudh delivers a fresh soundtrack that works for most parts!".[27] Behindwoods rated 3.5 out of 5, stating "Anirudh officially kick starts Kaththi celebrations!"[28] Indiaglitz rated 3.5 out of 5 stating "This is the best  OST for a Vijay starrer in the recent years, and Anirudh has made full use of the given opportunity to establish himself as one of the best among the current lot."[29] Moviecrow rated 6/10 stating "This much awaited album combo boasting the untested combination of Vijay-Anirudh-AR Murugadoss is sort of a let down. Lack of an instantly catchy song and the Anirudh's signature melody song are major shortcomings in the album."[30] MusicAloud gave 8 out of 10 stating that "Good mix of songs from Anirudh that should work well for an Ilayathalapathy movie."[31] Desi Music Bazaar rated 3.5 out of 5 stating "Anirudh once again proves that he is a youth-friendly composer. With tracks that are peppy and catchy, this album is sure to stay on the charts for a long time."[32]

The original background score of Kaththi was released by Anirudh Ravichander, in a jukebox format through his official YouTube channel on 28 January 2015, to coincide with the film's 100th day celebration as well. It features six original scores, composed by Anirudh. The OST album was released in all digital platforms on 1 February 2015.

Credits adapted from CD liner notes[33]