AdiIRC is constantly being developed and improved. It's among the most actively developed IRC clients nowadays, with a great beta team behind it. The changelog shows multiple substantial releases every month.

Nick Column feature support too.

It's a free IRC client supported by donations.

It works perfectly with Windows 10, has all the needed functions like:
1 - handle all irc:// links.
2 - start with windows.
3 - start minimized.
4 - close to tray icon when pressing X(close button).
5 - it can open all the channels in one window or open each channel in new windows (it is up to you).
6 - tons of options to pick up from.

Configurations, scripts and snippets are saved within the installation folder, allowing you to easily move them to a different installation. It also means that nothing is changed in your system.

Does not create registry keys.
Does not create any other folder than it's own on any other location.
Even when the installer is used, you can make it portable by just moving the folder around, don't need to worry about anything else.

Feature requests, suggestions and bug reports get prompt feedback.

A portable version is also available in the download section. It can be run without installation allowing it to be run off of external devices such as USB sticks.

You choose, Simple or Complex layout. Check the screenshots section in here.

miRC themes also works well in AdiIRC.

Supports Foobar2000, Winamp, QCDPlayer, iTunes, MusikCube, MediaMonkey, XMPlay, Spotify, VLC Media Player, Media Player Classic, MusicBee, PotPlayer and SMPlayer.

The vast majority of mIRC scripts/snippets work in AdiIRC, with compatibility constantly being improved.

Unlike hexchat, which needs to manually add a script.

Inline support for custom emotes and icons. Adding , removing or editing images replaces whole chat buffer tags in real time. AdiIRC makes your irc experience much more fun.

Plugins support too, with certain scripting languages to write.

Spellcheck for over 120 different languages is available. Full list of languages can be found here.

The user interface has full internationalization support and the developer is quick to integrate translations created by users or other contributors. Currently, full translations are included with the standard installation for Danish, German, Polish and Brazilian Portuguese.

The application can be configured to search for available updates at user-defined intervals for both the Stable and Beta release channels, and provides a dialog which automatically retrieves the updated installer and launches it.

You can modify or add your own hotkeys to your desire function.

You can monitor any event you like via a dockable panel that will record and optionally notify you upon detection of anything matching the set criteria.

The standard installer includes several standard color schemes to choose from, and it is possible from within the Options dialog to export any that you customize or create to share with others, or import those shared by others. The syntax of the file which defines them is well-documented and can be modified in any text editor if desired.

The client weighs less than 1MB.
Low CPU usage. Almost no CPU usage, in fact...

IRC is still very much alive and the protocol specification continues to evolve with new features and standards developed and published by the IRCv3 Working Group. As part of their work, they track the adoption and implementation of the specification they publish, and they announced on their website that as of the release of AdiIRC v3.9 on September 30, 2020, it was the first IRC client they were aware of to correctly implement support for all of the features in the current IRCv3 spec. This was accomplished only five months after two of the major IRCd servers (InspIRCd and Oragono) had released versions implementing all of those same features.