Dropping upstream Nix from Determinate Nix Installer

In early 2026, we plan to stop distributing upstream Nix via Determinate Nix Installer and to switch to distributing only Determinate Nix.

We’ve seen incredible success with Determinate Nix Installer. It performs nearly a million installations every month and has been chosen by countless users and organizations as their gateway to Nix. We’re extremely proud to have provided the community with a next-generation installer that works reliably across a broad range of environments.

But the installer is just the beginning of the great work we’ve done to make Nix better.

We believe strongly that Determinate Nix is the best way to build and distribute software and development environments and we’ve worked hard to ship meaningful improvements to our users. That means lazy trees, parallel evaluation, native Linux builders on macOS, stable flakes, and countless smaller developer experience touch-ups.

That’s why we’re taking the important step of sunsetting support for installing upstream Nix with Determinate Nix Installer.

I know this may be disruptive to some users, and I do apologize for that. Our motivation for this change is focus. I want my team to concentrate their efforts on giving our users the best Nix experience that we can muster.

We’re targeting users who want more than just a good Nix installer: we’re targeting users who want a better Nix experience altogether. I believe that Determinate Nix is that substantive improvement, across incredible evaluation performance, developer experience, and reliability.

If you don’t want that, that’s okay! The Nix community’s Nix Installer Working Group has published an experimental fork of our installer that only installs upstream Nix. I sincerely hope that this becomes the de facto standard installation tool for upstream Nix. We’re grateful for the community’s work and happy to continue our three-year collaboration on adopting it.

But if you do like our work, I hope that you stick with us as we create the best Nix experience we possibly can. I want to deliver that in the most determined and focused way we can.

In sum, here’s is what you need to know:

Determinate Nix Installer will only install Determinate Nix no sooner than January 1, 2026.

To that end, we’ll be shipping these changes over the next few weeks:

1. We’ll update our documentation to only show instructions for Determinate Nix.
2. Starting with the next release, Determinate Nix Installer and the DeterminateSystems/nix-installer-action on GitHub will start warning users of this change with a link to this intent-to-ship blog post.
3. The installer will accept a new flag, --prefer-upstream-nix, that tells the installer that you specifically want upstream Nix for automated installations.

Then, starting on November 10, 2025:

1. Running the installer like this with the command below will switch to installing Determinate Nix unless you apply the --prefer-upstream-nix flag:

   curl -fsSL https://install.determinate.systems/nix | \
     sh -s -- install --no-confirm

2. Our installer Action, DeterminateSystems/nix-installer-action, will switch to installing Determinate Nix unless determinate: false is passed.

Finally, starting no sooner than January 1, 2026:

1. Determinate Nix Installer will no longer prompt for Determinate Nix and will always install Determinate Nix. The --prefer-upstream-nix flag will no longer have an effect.

2. DeterminateSystems/nix-installer-action will also always install Determinate Nix.

I don’t relish this choice but I think it’s the right way to go. Why? Because we as a company neither own nor control upstream Nix, and that’s a good thing. But we want our installer to deliver something that we do control and are directly responsible for.

The Action will continue to warn users about this intent-to-ship change, which is declared in this GitHub issue.

Please contact us at support@determinate.systems if you have feedback about our intentions or our plan of action.