What tools or plugins do you find indispensable in your mastering chain, and how do you integrate them into your workflow?

DMG EQ and Limiter. 

Dynone multiband compressor

Kclip 

Waves L2

Toneprojects Kelvin. 

ATR tape emulation from UAD. 

But basically if the mix is good enough a hard clipper and a limiter would be the only indispensable tools. 

There are a few tools and plugins in my mastering chain that I consider absolutely indispensable. First, the API 2500 compressor is one of my go-to options. This plugin is incredibly versatile and works especially well when used on the mix bus during the mastering phase. The API 2500’s ability to add punch and glue to the mix without sacrificing clarity is something invaluable. It allows me to design the dynamics in ways that maximize the cohesiveness of the track, bringing all the elements together and creating a tight, controlled low end.

Another important plugin in my workflow is Pultec EQ emulation. Pultec is known for its unique ability to add warmth and character to the mix. I usually use it to enhance the lows or add some shine to the highs, this helps me achieve a fuller sound, even by making very small adjustments, which is typical in mastering.

After the EQ, I usually include a saturator or tape machine. This step is crucial for adding harmonic richness and subtle distortion, which can really bring a track to life. Tape saturation, in particular, is useful when dealing with harshness in the mix, as it smooths out these frequencies and adds a pleasing warmth. This can make digital mix sound more natural and dynamic, adding depth and warmth.

Finally, a limiter is indispensable at the end of my mastering chain. It's essential for maximizing the loudness of the track without introducing distortion or sacrificing dynamic range. Often, I will use a clipper before the limiter. Clipping before limiting is a technique that helps to control the peaks and improve the response to transients. By trimming the transients slightly before hitting the limiter, I can achieve a louder and more impactful master while preserving the punch and clarity of the original mix.

However, it's important to remember that while these tools are crucial, it's not just the equipment that makes a great master, it's the experience and taste behind the decisions. A truly outstanding master comes from understanding how to use these tools effectively and having the artistic sensibility to make the track shine.
 

None. It always depends on the mix you're working on. If the mix is great, the only thing you need to do is usually to make it slightly louder, that's it  At the mastering stage less is more.

I'd definitely say Ozone! It's super versatile and the Maximizer in particular is the best way I've found to get streaming-ready loudness whilst maintaining transients and dynamic range.

I also think if you want a plugin to give you instant excitement even whilst writing then OTT is a great one if you use it lightly, and it's free!