Bitwarden is the shit. As if the free tier werenāt good enough, the annual subscription is dirt cheap and you donāt have to remember more than the master password anymore.
My worker cooperative helps authors self-publish, and we use as much open-source as possible to do that. We rely almost exclusively on a number of tools which are all better than proprietary counterparts for one reason or another (sometimes merely because they are free and allow us to keep costs minimal) but the main reason is most of our clients value unquestioned data ownership over anything else. We avoid corporate cloud services and self-host as much as possible, for example.
Having said that, IMO many of these are also better designed and better UI than comparable paid tools. Blender being the obvious best example, but WordPress is another one. I used to ignorantly shit on WP so much when I was working in the professional startup industry as a web developer. Since then, I've learned to my delight that it's awesome if you don't bog it down with a bunch of horrible plugins, and the latest versions with their block editor approach are so good for easy and quick theming.
Here's a list off the top of my head of our regularly used software. I'm sure I'm forgetting some, and many of these are going to be unsurprising:
Linux (seems obvious, but definitely worth mentioning. We primarily use Ubuntu and Debian based images.)
Caddy (web server with dead-simple config and automatic https support)
Zulip (chat, the threading style they use is so effective for organizing discussions about client work, it's miles beyond Slack or any other options we've all used in past corporate lives)
Wordpress even has activitypub integration now! Hooray! Here's hoping automattic do good on their word and bring it to their other projects like Tumblr
Also as much as I like gimp, it is unfortunately not that widely used due to super specialised and hard to use compared to the industry standard juggernaut that is adobe's creative suite. You're probably going to get laughed at in any professional industry if you suggest seriously using it.
Proxmox VE makes this easy. Also makes building a cluster of such hypervisors easy. Thereās a free version that gives you the entire feature set but you need to pay for support and access to the Enterprise repository.
Itās not the only option, and it may not even be the best option, but itās pretty damn good.
I'm not even talking about proxmox, I'm talking about straight up QEMU with virt-manager on any RHEL like distro. Better yet if you have cockpit installed.
Not really client software but proxmox is damn useful. It's replaced any hypervisors at at least 2 companies I've been in IT at. It's not going to run your multi-national datacenters, but for the 2 or 4 locations on a low budget, with a need for Virtualization Proxmox makes it easy.
Argo workflows and Argocd (vs. something like Harness) - Requires a handful of customizations to get it parity, but it's really useful out-of-the-box I think. Good ol' Jenkins works too, I suppose.
Soon, OpenTofu - unfortunately Hashicorp is going IPO which means bad news. OpenTofu is the fork of terraform.
Podman - Docker alternative. It's really close, especially with Podman Desktop. I had a few issues that I ran into, but there are probably workarounds.
Vscode / codium - yeah it's Microsoft, and has tracking. But it's popular for a reason.
TrueNAS Scale. Itās based on Debian instead of FreeBSD (like TrueNAS Core) and has KVM virtualization and k3s containerized app support built in, in addition to being a NAS operating system.