The Chainsmokers

In their reddit ama, when asked, "What is your studio and live setup?", The Chainsmokers reply, "Studio: Ableton Live... record a lot of guitar recently on telecaster. fav vsts atm are xfer serum and omniphere 2. Live Pioneer CDJs atm but we are experimenting incorporating live elements into our set up"

The Chainsmokers talk about some of their favorite VST plugins they use in the studio in their reddit ama. One of the ones they mention is Spectrasonics Omnisphere 2:

"Studio: Ableton Live... record a lot of guitar recently on telecaster. fav vsts atm are xfer serum and omniphere 2."

In this interview with Drew Taggart of The Chainsmokers, he mentions that this popular drum synthesizer is one of his favorites.

At 28:52 in the video, he pulls up the Waves SSL E-channel plugin that he uses for the acoustic guitar record in the song "Roses"

This item is used by The Chainsmokers, because at 08:47 min. of the video an audio file named "VEH2-Claps-", which is loaded into the " Drum Rack" of Ableton Live, can bee seen.

Here we see him explaining how he did his sidechain on their track 'Roses". 40 seconds ish in is when you see him with kickstart.

“This is a plugin that’s been around for so long that people have got bored with it. I think that’s because they haven’t taken the time to make it their own. Experiment, get off the beaten track, and it will deliver. The bass in #Selfie came from Sylenth1, and for that, I will be eternally grateful!”

At 25:50 in this video from Future Music Magazine, Andrew Taggart of The Chainsmokers talks about using Reaktor for creating a bass sound for their track "Roses".

In this interview with MusicRadar, Drew Taggart says he uses Nexus.

In this video with Future Magazine in wich they show the making of roses, we can clearly see at minute 19.53 that they are using waves cla vocals.

In the ABC News video titled "The Chainsmokers | Inside the Studio with Alex Pall, Drew Taggart," at the 0:49 mark, Serato DJ Pro software is visible on an Apple MacBook Pro, indicating its use by The Chainsmokers in their studio sessions.

Massive can be seen at 44:37 in this video

At 8 seconds into the video, you can see The Chainsmokers tweaking a knob belong to Spire.

Guitar Rig 5 was used on the guitar on "Don't Let Me Down".

At 14:32 in this video from Future Music Magazine, Andrew Taggart of The Chainsmokers talks about using Melodyne for a small portion of the vocals in their track "Roses".

At 1:15 in the video, there is clearly an audio clip in red that says VES1 FX

In this YouTube video at 22:05 minutes there is an audio file to be seen named "HK..", which is a sample from a sample pack by hitkitsamples.com used by various big name music producers

In an episode of Tape Notes, Drew Taggart of The Chainsmokers confirmed the use of Xfer Records LFOTool on the guitars in their song "If You're Serious," as discussed in detail during their exploration of the track's Ableton session.