DevEstimates
I made a tool to turn my spreadsheet for project estimation into a slightly better web app experience. The premise is that project estimates (how long will feature X take to ship) tend to be extremely inaccurate and moderately toxic BUT if you don't /try/ to make them accurate you can still get useful project data.
This is essentially the 2 outside estimates from the "3 point estimate" project management paradigm -- I ask everyone working on the project for two intentionally extreme estimates - a mythical ship date if everything went impossibly well (works on the first try, the designs don't change, nothing pulls you away, etc) and a date that is intentionally after the ship date if absolutely everything goes wrong. These are extreme enough it tends to take the stress out of picking a date, they can be given from the hip in 30 seconds, and they obviously can't be weaponized as 'actual estimates' so there isn't as much fear that some manager somewhere will try to hold anyone to them as a deadline.
There is no resulting "this will probably ship on date X/Y/Z" answer but it has been extremely helpful on my team so far since you can learn a lot from the relationships between the guesses - big gaps between team members means we're not on the same page, everyone jumping up means requirements just got changed or discovered, the guesses growing at the same rate week over week means we don't feel like we're making progress, etc.
It has been a surprisingly effective tool when using it this way but I'm the first to admit it isn't for everyone since it does NOT spit out a "when will this ship" date and it actually just tells the project leader where to go do more legwork (and I think it takes a rare, mindful person to like using a tool that tells them to go work more - doesn't feel like a pain killer OR a vitamin). As a secondary benefit it has also been helpful for folks (me included) to reflect on our estimation accuracy after the project ships.
I've made it in a "maybe this could make money one day if other people unexpectedly want this too" but I don't expect that and I honestly kind of love the project being just for my use case and not having customers - the writing is snarky (eg, "Estimating sucks but most businesses still demand estimates from their makers anyway..."), the ui is brutalist and minimal (no design framework other than the ironically named classless.css), and it is not very feature bloated yet. I have had fun throwing spaghetti code around and not worrying about breaking things for customers or impacting other team members.
At this point the project is (minimally) feature complete and I'm using it for my real life work - I'm in the last stage of deciding where it is going to live in production so hopefully it can 'go live' next week instead of living on my laptop. I'll make a proper HN post at that point so y'all can roast me into oblivion since I need to be taken down a peg every once in a while.