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Developer Tools · head to head

Blacksmith vs NixOS

Blacksmith logo

Blacksmith

Developer Tools

2x faster GitHub Actions with 60% cost savings

From
Free
Rated
-
Full reviewWebsite
NixOS logo

NixOS

Operating Systems

Linux distribution where the whole machine is defined in one declarative configuration and every change can be rolled back

From
Free
Rated
-
Full reviewWebsite

The short version

  • Each has a real cost: Blacksmith per-minute pricing model requires estimating usage to predict costs; NixOS the Nix language is a prerequisite, not an optional extra, and error messages are frequently unhelpful, so the first month of adoption is slow for even experienced administrators.
  • They diverge on capability: Blacksmith covers Bare metal runners, NixOS covers Declarative configuration.
  • Prices and features above were last checked on 31 August 2026.

Where they differ

Only the attributes on which Blacksmith and NixOS actually diverge.

Attributes where Blacksmith and NixOS differ
AttributeBlacksmithNixOS
Pricing modelUnknownOpen source, no licence fee
PlatformsGitHub Actions, Linux, Windows, macOSx86-64, ARM64, WSL, Containers, Cloud images, macOS via Nix package manager
CategoryDeveloper ToolsOperating Systems

Identical on both: starting price (Free), free tier (Yes), user rating (Not yet rated).

What each one covers

Drawn from each product's published feature list. An absence here means we hold no record of it - not that the product lacks it.

Only in Blacksmith

  • Bare metal runners
  • Multiple OS support
  • ARM support
  • Docker layer caching
  • Sticky disks
  • GitHub Actions observability
  • Free tier
  • Static IPs

Only in NixOS

  • Declarative configuration
  • Rollbacks by generation
  • Reproducible builds
  • Nixpkgs
  • Development shells
  • Home Manager

What people use each for

The jobs each tool is most often brought in to do.

Blacksmith

  • Replacing GitHub Actions runners with faster, cheaper infrastructurenot NixOS
  • Accelerating CI build times for organizations with heavy CI loadnot NixOS
  • Reducing cloud spend on GitHub Actions by 60% or morenot NixOS
  • Supporting ARM architecture builds without GitHub runnersnot NixOS

NixOS

  • Fleets where every machine must be provably identical rather than approximately identicalnot Blacksmith
  • Build and CI infrastructure that has to reproduce an old toolchain exactly, years laternot Blacksmith
  • Developer workstations where each project pins its own compiler and library versionsnot Blacksmith
  • Servers where an unattended upgrade must be revertible at boot without a restorenot Blacksmith

Where each one falls short

Documented limitations, not opinions. Every one is a constraint you would hit in normal use.

Blacksmith

  • Per-minute pricing model requires estimating usage to predict costs
  • macOS M4 pricing ($0.08/min) is significantly higher than GitHub Actions
  • Docker layer caching and sticky disks are paid add-ons at $0.50/GB/mo
  • Static IP add-on costs $100/IP/mo

NixOS

  • The Nix language is a prerequisite, not an optional extra, and error messages are frequently unhelpful, so the first month of adoption is slow for even experienced administrators.
  • Flakes have been the practical standard while still marked experimental, which splits tutorials, blog posts and manuals into two incompatible styles and makes searching for answers frustrating.
  • There is no conventional filesystem hierarchy, so downloaded binaries, vendor installers and anything expecting /usr/lib fail until wrapped with steam-run, an FHS environment or patchelf.
  • Old generations and the store consume disk aggressively, and a machine that is never garbage collected will fill its root partition without any obvious cause.
  • Anything not already in Nixpkgs has to be packaged by you, which turns a five-minute install on another distribution into an afternoon of writing a derivation.

Pricing, plan by plan

Blacksmith

Free
  • Ubuntu x64$0.004/minute
    • 3,000 free minutes per month
    • 2x faster hardware
    • 4x faster cache downloads
  • Ubuntu ARM$0.0025/minute
    • 3,000 free minutes per month
    • 2x faster hardware
    • 4x faster cache downloads
  • Windows x64$0.008/minute
    • 3,000 free minutes per month
    • 2x faster hardware
    • 4x faster cache downloads
  • macOS M4$0.08/minute
    • 3,000 free minutes per month
    • 2x faster hardware
    • 4x faster cache downloads

NixOS

Free
  • NixOSFree
    • No licence fee or registration
    • All packages and channels
    • Binary cache hosted by the project

Which should you pick?

Choose Blacksmith if

  • You need bare metal runners.
  • You want to start without paying.
  • You work on GitHub Actions, Linux, Windows, macOS.
  • You also want multiple os support.
Blacksmith review

Choose NixOS if

  • You need declarative configuration.
  • You want to start without paying.
  • You work on x86-64, ARM64, WSL, Containers, Cloud images, macOS via Nix package manager.
  • You also want rollbacks by generation.
NixOS review

Questions people ask

Is Blacksmith or NixOS better?
Neither clearly leads. Blacksmith starts at Free and NixOS at Free, and user ratings are close enough to be indistinguishable. Choose on capability and platform support.
Which is cheaper, Blacksmith or NixOS?
Blacksmith starts at Free and NixOS at Free.
Does Blacksmith or NixOS run on more platforms?
Blacksmith runs on GitHub Actions, Linux, Windows, macOS. NixOS runs on x86-64, ARM64, WSL, Containers, Cloud images, macOS via Nix package manager.
Can I use Blacksmith for free?
Both have a free tier, so you can try either at no cost before committing.
What is Blacksmith best used for?
Blacksmith is most often used for replacing github actions runners with faster, cheaper infrastructure, accelerating ci build times for organizations with heavy ci load, reducing cloud spend on github actions by 60% or more, supporting arm architecture builds without github runners. Of those, replacing github actions runners with faster, cheaper infrastructure and accelerating ci build times for organizations with heavy ci load are not what NixOS is typically brought in for.
What can Blacksmith do that NixOS cannot?
Blacksmith covers Bare metal runners, Multiple OS support, ARM support, Docker layer caching. NixOS covers Declarative configuration, Rollbacks by generation, Reproducible builds, Nixpkgs.

Answered from the vendors’ own pages

Blacksmith: How much do Blacksmith runners cost compared to GitHub Actions?

Blacksmith offers 60-75% cost savings depending on OS. Ubuntu x64 costs $0.004/min vs GitHub at $0.012/min. All plans include 3,000 free minutes monthly.

Source
NixOS: Do I need NixOS to use Nix?

No. The Nix package manager and development shells work on other Linux distributions and on macOS, which is how most teams try it before committing a machine to NixOS.

Blacksmith: Can I use Docker layer caching with Blacksmith?

Yes, Docker layer caching is available as an add-on at $0.50/GB/mo. Managed Docker layer persistence is included with the base service.

Source
NixOS: Are flakes safe to use in production?

They are widely used in production and are the standard way to pin inputs, but they are still formally experimental and must be enabled by a flag. Treat the documentation split as the real cost, not instability.

Blacksmith: What is the SLA for Enterprise plans?

Enterprise Blacksmith plans include a 99.9% SLA guarantee along with 24/7 priority support, dedicated Slack channels, white-glove onboarding, and CI optimization support.

Source
NixOS: What happened to the project leadership?

The founder stepped back as project lead in 2024 following a public governance dispute, an elected steering committee took over direction, and a fork drew off some contributors. Nixpkgs development continued throughout.

NixOS: How often are releases made?

Twice a year, versioned by year and month, plus a continuously updated unstable channel that many desktop users track instead.

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