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Blacksmith vs Nixpacks

Blacksmith logo

Blacksmith

Developer Tools

2x faster GitHub Actions with 60% cost savings

From
Free
Rated
-
Full reviewWebsite
Nixpacks logo

Nixpacks

Developer Tools

Build system that turns a source directory into an OCI image, now in maintenance mode

From
Free
Rated
-
Full reviewWebsite

The short version

  • Each has a real cost: Blacksmith per-minute pricing model requires estimating usage to predict costs; Nixpacks the project is in maintenance mode with no commits on the default branch since May 2026 and no release since October 2025, so support for new language versions arrives only if someone forks it.
  • They diverge on capability: Blacksmith covers Bare metal runners, Nixpacks covers Automatic language detection.
  • Prices and features above were last checked on 31 August 2026.

Where they differ

Only the attributes on which Blacksmith and Nixpacks actually diverge.

Attributes where Blacksmith and Nixpacks differ
AttributeBlacksmithNixpacks
Pricing modelUnknownOpen source, no licence fee
PlatformsGitHub Actions, Linux, Windows, macOSLinux, macOS, CLI, Docker

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

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
  • Sticky disks
  • GitHub Actions observability
  • Free tier
  • Static IPs

Only in Nixpacks

  • Automatic language detection
  • No Dockerfile required
  • Nix toolchains
  • Configuration escape hatches

Both cover

  • Docker layer caching

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 Nixpacks
  • Accelerating CI build times for organizations with heavy CI loadnot Nixpacks
  • Reducing cloud spend on GitHub Actions by 60% or morenot Nixpacks
  • Supporting ARM architecture builds without GitHub runnersnot Nixpacks

Nixpacks

  • Understanding the build behaviour of a platform that adopted Nixpacks before it was frozennot Blacksmith
  • Producing container images from a polyglot monorepo where nobody wants to own several Dockerfilesnot Blacksmith
  • Reproducing an existing Railway build locally while planning a migration to Railpacknot Blacksmith
  • Comparing what a Nix based builder does differently from a buildpack before choosing a successornot 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

Nixpacks

  • The project is in maintenance mode with no commits on the default branch since May 2026 and no release since October 2025, so support for new language versions arrives only if someone forks it.
  • Build determinism is softer than it appears, because providers pin a nixpkgs archive commit and bumping that archive silently moves compiler and runtime versions underneath a build that looks unchanged.
  • Caching is limited to Docker layers rather than a content addressed graph, so a small change early in the build invalidates everything after it, which is exactly the limitation Railpack was rewritten to fix.
  • Images carry Nix store layers and come out larger than an equivalent tuned Dockerfile or buildpack output, which costs registry storage and slows cold pulls on scale-out.
  • There is no specification, no vendor neutral governance and no third party provider ecosystem, so a single company was able to redirect strategy and leave every downstream user with a frozen build tool.

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

Nixpacks

Free
  • NixpacksFree
    • MIT licensed, no usage limits
    • No commercial edition and no support contract
    • In maintenance mode, superseded by Railpack

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 Nixpacks if

  • You need automatic language detection.
  • You want to start without paying.
  • You work on Linux, macOS, CLI, Docker.
  • You also want no dockerfile required.
Nixpacks review

Questions people ask

Is Blacksmith or Nixpacks better?
Neither clearly leads. Blacksmith starts at Free and Nixpacks at Free, and user ratings are close enough to be indistinguishable. Choose on capability and platform support.
Which is cheaper, Blacksmith or Nixpacks?
Blacksmith starts at Free and Nixpacks at Free.
Does Blacksmith or Nixpacks run on more platforms?
Blacksmith runs on GitHub Actions, Linux, Windows, macOS. Nixpacks runs on Linux, macOS, CLI, Docker.
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 Nixpacks is typically brought in for.
What can Blacksmith do that Nixpacks cannot?
Blacksmith covers Bare metal runners, Multiple OS support, ARM support, Sticky disks. Nixpacks covers Automatic language detection, No Dockerfile required, Nix toolchains, Configuration escape hatches. Both handle Docker layer caching.

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
Nixpacks: Should I start a new project on Nixpacks?

No. The documentation and README both say it is in maintenance mode and recommend Railpack. Choose Railpack, Cloud Native Buildpacks or a Dockerfile instead.

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
Nixpacks: Will my existing Nixpacks builds stop working?

Not immediately. Pinned nixpkgs archives keep resolving, so builds continue. What you lose is support for new runtime major versions and any fix for a provider bug.

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
Nixpacks: What replaces it?

Railpack, also from Railway and also MIT licensed, rebuilt as a BuildKit custom frontend for finer grained caching and parallel steps.

Nixpacks: Is it still open source?

Yes, MIT, and the repository is not archived. Being open source does not help much when nobody is merging provider updates.

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