I maintain a ~250K LoC Zig compiler code base [0]. We've been through several breaking Zig releases (although the code base was much smaller for most of that time; Writergate is the main one we've had to deal with since the code base crossed the 100K LoC mark).

The language and stdlib changing hasn't been a major pain point in at least a year or two. There was some upgrade a couple of years ago that took us awhile to land (I think it might have been 0.12 -> 0.13 but I could be misremembering the exact version) but it's been smooth sailing for a long time now.

These days I'd put breaking releases in the "minor nuisance" category, and when people ask what I've liked and disliked about using Zig I rarely even remember to bring it up.

[0]: https://github.com/roc-lang/roc

I've worked on two "production" zig codebases: tigerbeetle [0] and sig [1].

These larger zig projects will stick to a tagged release (which doesn't change), and upgrade to newly tagged releases, usually a few days or months after they come out. The upgrade itself takes like a week, depending on the amount of changes to be done. These projects also tend to not use other zig dependencies.

[0]: https://github.com/tigerbeetle/tigerbeetle/pulls?q=is%3Apr+a...

[1]: https://github.com/Syndica/sig/pulls?q=is%3Apr+author%3Akpro...

Zig 0.15 is pretty stable. The biggest issue I face daily are silent compiler errors (SIGBUS) for trivial things, e.g. a typo in an import path. I've yet to find exactly why this [only sometimes] causes such a crash, but they're a real pain to figure out over a large changeset. `zig ast-check` sometimes catches the error, else Claude's pretty good at spotting where I accidentally re-used a variable name (again, 90% of the time I do that, it's an easy error, but the other 10%, I get a message-less compiler crash). It sounds like the changes in the OP might be specifically addressing these types of issues.

Also, my .zig-cache is currently at 173GB, which causes some issues on the small Linux ARM VPS I test with.

As for upgrades. I upgraded lightpanda to 0.14 then 0.15 and it was fine. I think for lightpanda, the 0.16 changes might not be too bad, with the only potential issue coming from our use of libcurl and our small websocket server (for CDP connections). Those layers are relatively isolated / abstracted, so I'm hopeful.

As a library developer, I've given up following / tracking 0.16. For one, the change don't resonate with me, and for another, it's changing far too fast. I don't think anyone expects 0.16 support in a library right now. I've gotten PRs for my "dev" branches from a few brave souls and everyone seems happy with that arrangement.

The forever backwards compatible promise of C++ was a tremendous design mistake that has resulted in mindshare death as of 2026. It might suck to have to modify your code to continue to get it to work, but it’s the right long term approach.

It's been a non-issue for us at tvScientific. Once or twice a year you settle in for a mass refactor, and when that's done you move on with your day.

Packages do fall behind. We only use a couple, so it's pretty easy to point to an internal fork while we wait for upstream to update or to accept our updates. That'd probably be a pain point if you were using a lot of them.

The language itself does not change much, but the std does. It depends on individuals, but some people rely less on the std, some copy the old code that they still need.

> Are there cases where packages you may use fall behind the language?

Using third party packages is quite problematic yes. I don't recommend using them too much personally, unless you want to make more work for yourself.

I recently tried to learn it and found it frustrating. A lot of docs are for 0.15 but the latest is (or was) 0.16 which changed a lot of std so none of the existing write ups were valid anymore. I plan to revisit once it gets more stable because I do like it when I get it to work.

I stopped updating the compiler at 0.14 for three projects. Getting the correct toolchain is part of my (incremental) build process. I don't use any external Zig packages.

I think one of the more PITA changes necessary to get these projects to 0.15 is removing `usingnamespace`, which I've used to implement a kind of mixin. The projects are all a few thousand LOC and it shouldn't be that much trouble, but enough trouble that none of what I gain from upgrading currently justify doing it. I think that's fine.

Mitchell Hashimoto (developer of Ghostty) talks about Zig a lot. Ghostty is written in it, and he seems to love it. The churn doesn't seem to bother him at all.

I asked him about in a thread a while back: https://news.ycombinator.com/item?id=47206009#47209313

The makers of TigerBeatle also rave about how good Zig is.

> I know Bun's using zig to a degree of success, was wondering how the rest were doing.

Just a degree of success?

You can fix you code 10 times you will fix it.

For those like me who have never heard of this software: Bun, some sort of package management service for javascript. https://en.wikipedia.org/wiki/Bun_(software)