What is?

List of freely available (mostly FOSS) software for Windows that makes using it a little nicer. Some are available for other platforms.

Some tools in this list require more setting up than just install-and-go. These are denoted with an asterisk (*) by their names.

Many tools are donationware. Please consider supporting development if you end up using any of these tools a lot, or if they make your life better.

shareX*

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Screenshot, screen recording, color picker, among other things.
Can be used right out the box, but has extensive settings catalogue. I've mapped my screenshot, region screenshot and region screen record keys to match macOS and it's great. Windows' built-in screenshot tool is definitely capable, this just beats it for me.

PowerToys by Microsoft

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Collection of tweaks and better-making features direct from Microsoft, with ability to turn each one on/off. Especially useful for things like adding SVG thumbnails/previews in Explorer, which for some reason isn't included by default. Also has:

• a bulk renaming feature if the options in Bulk Renaming Utility (above) are too complex.
• "PowerToys Run": essentially MacOS' Spotlight Search
• Key remapper: if like me you got far too used to how the Apple keyboard layout was
• one-click image resizer

peazip

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archive tool.
Deals with pretty much all archive formats, include a fair few the built-in Windows archive utility does not. Not sure how prevalent RAR files are nowadays, but man, back in the day...

teracopy

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Replaces the built-in Windows file copy / move utility and adds support for retries, validity checks and lists of what's succeeded or failed in copying/moving. Useful when dealing with things that have a lot of files.

winaero tweaker*

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A program that provides a whole host of tweaks to help you get your Windows looking and behaving just as you want.
Note that this is in some cases a tool for tweaking registry values, so back up your registry before using registry-altering tweaks.

audacity

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Audio editing program. Requires separate download of the LAME library in order to export MP3 files

rainmeter*

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Desktop customiser du jour circa the mid-2000s. Lets you add / create skins to display different things on the desktop, like storage and computer performance, clocks, music, music visualisations and more

musescore

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music notation creation and reading software similar to Guitar Pro

MusicBee

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music player with extensive list of tweakable settings. Essentially the "make the music player you want to have". Supports streaming radio, podcasts and local play

Bulk Rename Utility

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Windows doesn't have very good file renaming options. This fixes that! I'd go as far as to say this is better than the default macOS bulk renamer, too.

Miro video converter

http://www.mirovideoconverter.com/download_win.html
Want that video to be in a different format? How about an audio file instead? For free you say? Easily?

Pencil (flowcharts)

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Diagram-making software. Has built-in stencil sets for basic flowcharts, phone/web mockup-ery, is good.

HandBrake*

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More in-depth video / audio / streaming media transcoder than is Miro.

Caesium Image Compressor

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Simple image compressor / resizer.