A so-called "productivity tool" will save you 15 minutes a day. Asking questions and thinking will save you weeks of work.
More on productivity here: https://codewithoutrules.com/2016/08/25/the-01x-programmer/
That is probably my number one productivity tool.
The next most important tool is moving everyone to an established process where all requests/bugs/tasks have to come through a single channel. In this case, the channel is Jira for me. Before this, things could come from many different channels. Having things all in one place ensures things do not fall through the cracks. It gives you the ability to see a big picture view of what is going on.
For smaller teams, it might not make sense to use something big like Jira, but none the less, having a process in place really helps.
- Computing power of course.
- magit: I cannot imagine using git without it. This and org-mode are still the reasons why I use Emacs.
- IntelliJ: My younger, stupid self always felt proud of using spartan tools (spartan, as in "emacs is too bloated and the only thing I need are ed or mg and how dare you using a mouse"). Fortunately I grew up and abandoned all sort of tribalistic or elitist thoughts. IDEs are an invaluable tool and I feel sorry for the suckers that are still trapped on the "programmers that use IDEs are inherently stupid" narrative.
- TOAD SQL & Winmerge: I don't work with Windows anymore but miss these two daily. Let me know if you know of tools that are similar for macOS / Linux.
- cwm: I rarely use it anymore as I don't boot my OpenBSD box as much as I'd like but it has this thing where you press M-/ (I think?) so you can query windows by name. It's really useful. So are groups.
- Ctrl-up & Ctrl-down in macOS. Win+tab in Windows.
- Windowmaker's Dockapps. I miss those.
- ACME: You don't know what you're talking about when you say "UNIX as IDE" if you haven't tried this.
- vi keybindings.
- A internal wiki: 1/4 of my time is spent writing or reading it.