Ask HN: What are some tools / libraries you built yourself?

That was a good guess! Your comment provided some helpful motivation to go look into it. :)

It seems to have actually been a typo-misuse of moment.tz's very similar but very different constructor patterns. To illustrate, imagine we have a date "2020-01-01", an offset tz "America/Vancouver", and "America/Toronto" as the locale's timezone.

moment(date).tz(offset) says "interpret date in its given tz, falling back to the locale tz if not given, then reinterpret it via the offset tz". So the date "2020-01-01" with no encoded tz data is interpreted as midnight in the locale's tz, America/Toronto. That is then reinterpreted in the offset timezone America/Vancouver, so calling .format() on it gives the result "2019-12-31T21:00:00-08:00" -- midnight on New Year's Eve in Toronto was 9 PM on Dec 31st in Vancouver. Offset here is changing the output, not the input.

moment.tz(date, offset) says "interpret date in its given tz, falling back to offset as the tz if not given". So the date "2021-01-01" with no tz data is interpreted as midnight in the offset tz, "America/Vancouver". Now calling .format() gives "2020-01-01T00:00:00-08:00", or midnight in Vancouver, which would be 3 AM in Toronto.

Glad to have it fixed.

I built Accelerator Keys, a niche tool replicating Windows accelerator key shortcuts in Mac Excel [0]. I made it to scratch my own itch at first, as accelerator keys are a much more intuitive and faster way to use a shortcut intensive app like Excel. Before this, power users needed to run a full VM and use Windows Excel if they wanted to use these shortcuts. It seemed like overkill to me.

Last year, I decided to take the leap and try selling my first piece of software. Here's the PH launch from a few months ago [1]. It's not easy tracking down users, but I've managed to sell a few hundred licenses so far.

It has been a fruitful journey. Learned a lot while building it (e.g. about accessibility features on Macs), but making this a product also meant learning about licensing, payments, front end for the landing page, SEO and FB ads.

[0]: https://acceleratorkeys.com

[1]: https://www.producthunt.com/posts/accelerator-keys

A couple of years ago, I went to work in SF area and I switched my dev environment for MacOS.

On my free time I love to do some apps and when I started to learn Swift and Cocoa, I got tired of dealing with same things with platform specific complicated stuff.

I decided to build by own GUI tool, written with the Go programming language.

A couple of iteration later (years), it became a WebAssembly library for building progressive web apps.

It is named go-app and you can see how it look like with this dogfooded documentation website: https://go-app.dev

If you like lofi music when working, or you are a fan of World of Warcraft game, there is those 2 others ones built with this package: https://lofimusic.app and https://murlok.io

Hope you find it interesting :)

Lately I wrote a small ssh client that allows you to take your configuration files (such as .bashrc, .vimrc) to the remote easily. Got too frustrated copying those manually as I have quite many remotes I work with and also because I like to tune my configs constantly. Also I have some ideas for further development once I have time for that.

https://github.com/drodil/envssh

10 years ago I built a little library / test app to support embedded Ruby development with a kind of Fuzx testing. One of the cool features of Ruby is that one thread can raise an exception in another thread.

So my library simply allows you to define a set of exceptions, with a distribution across them. The app runs an extra thread in parallel with the main app, and "carpet bombs" the main app with exceptions drawn from the desired distribution.

Very useful for checking that the code is resilient to all sorts of real world edge cases you haven't thought of!