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

There is no one miracle tool or solution - more important than using any one plugin is intent, and knowing what you're doing.

Do not add plugins and effects just for the sake of adding it. Instead, lean back, listen to the track and decide, what does this track need right now. Are the highs muffled and could use some sparkle? Are the low-mids a bit too muddy? Is the bass too wide and phasing? Are the drums sticking out of the track, or are the dynamics all over the place? 

With intention slowly you can layer the effects and craft your individual mastering chain for each and every project. Every song is different, but for me personally, often this ends up being a combination of the following Plugins:

EQ (Pro-Q3) → Resonance Surpression (Soothe2) → Compression (Glue Compressor) → Multiband Compression (ProMB / OTT) → Limiting (Pro L-2)

EDM & Dance engineer here!

In my mastering chain, a limiter is absolutely indispensable. I typically use two limiters for different purposes:

The first limiter acts as a clipper to catch and control peaks. 
The second limiter is for achieving that extra loudness while ensuring clarity. 

These two stages work in tandem to help me achieve the competitive loudness expected in modern dance music, while still preserving the energy and clarity that’s essential for a great-sounding master.

Hey there!

When it comes to music production, I believe in keeping things simple. I focus on getting the mix right before moving on to mastering. During mastering, my goal is to enhance the existing sound without making drastic changes, adding subtle touches only when necessary.

I usually rely on FabFilter Pro-Q 3 or Kirchhoff-EQ for my equalization needs. I've also been using Izotope Ozone for a long time. It has a bit of a learning curve, but once you get the hang of it, its power becomes evident.

For more in-depth processing, I might suggest trying out Bloom by Oeksound and Virtual Mix Rack by Slate Digital for a clean and modern sound. If you're looking for a vintage vibe, the Ampex ATR-102 Mastering Tape Recorder could be a good choice for chain coloring. However, it's important to be cautious with these tools, as they can significantly transform your mix and may not always be necessary if your mix already sounds great after the mixing stage.

The best mastering is when you don’t need any, but most tracks do need some work. A common issue is mixes that sound flat or over-compressed. They need volume changes to sound lively. Another issue is inconsistent vocal levels. You can fix this a bit by compressing the mid channel but be careful not to mess up anything else.

The must-have tools are good speakers, one "bad" bandlimited speaker (really!), a good room to listen in, headphones, fresh ears, and patience.

I mostly use hybrid chain. I love Shadow Hills mastering compressor or MAAG EQ4 for overall clarity. But nowadays great mastering can be done in the box as well.

Once I’ve got the analog color and glue, I bring it back into the box for precision. That’s where digital EQs like FabFilter Pro-Q come in handy for surgical tweaks, and digital multiband compression or limiters (iZotope Ozone Dynamics, Maximizer, Fabfilter L 2) allow me to fine-tune the dynamics and loudness. The key is getting that analog mojo without losing control over the details that digital tools excel at.

Throughout the process, I’m always bouncing between the analog warmth and digital clarity, making sure the two complement each other rather than clash. It’s all about harnessing the depth of analog while keeping the surgical precision of digital!

The essential tools for my work are compression, EQ, and limiting, provided they are quality tools with a lot of flexibility and features. For example, I look for capabilities like mid/side processing, dynamic functionality, and variable Q in an equalizer; sidechain input and stereo linking for compression; and lookahead for limiting. While I have many other tools that are useful for specific projects, I could manage most tasks with just these three fundamental tools. Of course, having good mastering software is also crucial—I typically use WaveLab Pro, Reaper, and iZotope RX.

The MCDSP ML4000 is a fundamental tool in my vocalchain, it is simply magical, it makes vocals recorded with $100 mics sound like $1000 mics. You must try it! 
If I have to mention another one it would be Soothe2, Fab L2.

Depends what budget you're on. But there are a few that I couldn't do without.

I absolutely love the UAD API2500. Its a lovely Compressor, super smooth and just helps glue everything together. (if I'm in the box)

I'll drive things a little with the UAD Studer A800 for that nice expensive saturation that tape gives.

I also have some analog gear which I like - the API 550bs are some really great EQs and the SSL Bus Compressor when I'm going full analog in place of the API 2500

I always use Ozone - its got some great dynamic EQ's which can be really handy in taking our problem frequencies and the master rebalance tool is super handy if someone has sent a song with the vocals too loud (can sneakily push them back). Its 'AI' function is a great starting point but it can be a little over zealous with its application of things so usually good to pair it back.

Then my secret weapon - BX master desk 2. I use this for literally one thing only and thats the widening. Its mad. So good.

Just my 50p there!