Mayer was spotted playing through Fractal Audio’s Axe-Fx III during a guest performance with Khalid at this weekend’s Coachella festival, during which he unleashed one seriously tasty lead tone

Pulled out the Marshall JTM45 mk II plexi today. Just like Jimi used to play. There aren’t many of these still standing. I don’t expect an overwhelming number of likes on this, but the ones I get are going to be valued at 2.4x because this is as badass as it gets.

In this picture from his Instagram account we can see he is using the Kemper for warming up.

We see Mayer using the amplifier. (the video is a demo and advertisement for the amp itself)

I got the sound going, it's 52' Fender Telecaster... and uh, an early 90's Dual Professional. I'll say it now because it's on of my favorite amps cause' I have a couple.

John Mayer shows his "custom" Fender Deluxe Reverb amp in this periscope video.

Just got one of the best new guitar amps I've heard in a very long time. Also here's a picture of my face. @milkmansound 85 watt steel guitar amp hand built by Tim Marcus in San Francisco. Plus my face. I put a JAN 5751 NOS tube in the v1 preamp stage and it sounds amazing. But if that's not your thing, don't worry. This is also a selfie.

In this source he lists what he is using in the description of the video.

As far as legendary amps...there's the Dumble amplifier made by Alexander Howard Dumble. The Steel String Singer doesn't have overdrive or anything. It's an amplifier that is clean sounding and yet is able to produce a great big sound. Alexander didn't make a whole lot of these but they are such strong amplifiers - Stevie Ray Vaughan used them, Bonnie Raitt used them. A lot of artists of back then were using these amps. If you wanted to call it a boutique amplifier, I guess you could but to me really it's just a double amp. One of the best amplifiers made in the world today.

John Mayer uses the Fender Hot Rod Series Blues Junior 15W 1x12 Tube Guitar Combo Amp during his live performances.

Blues guitarist John Mayer uses the Fender Vintage Reissue '65 Super Reverb 4X10 Guitar Amp, a powerful amplifier that stands out in his large collection of performance amps.

This Fender Hot Rod Series Blues Junior 15W 1x12 Tube Guitar Combo Amp is seen in use by blues guitarist and musician John Mayer during one of his many live performances.

To create his legendary, clean-cut sound, John Mayer uses a wide variety of amps, of which the Fender Vibro-King Custom 60W 3x10 Tube Guitar Combo Amp Black is included.