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Developer Tools · head to head

Bazel vs Blacksmith

Bazel logo

Bazel

Developer Tools

Multi-language build system with fast, correct incremental builds

From
Free
Rated
-
Full reviewWebsite
Blacksmith logo

Blacksmith

Developer Tools

2x faster GitHub Actions with 60% cost savings

From
Free
Rated
-
Full reviewWebsite

The short version

  • Each has a real cost: Bazel steep learning curve for developers unfamiliar with build systems; Blacksmith per-minute pricing model requires estimating usage to predict costs
  • They diverge on capability: Bazel covers Fast incremental builds, Blacksmith covers Bare metal runners.

Where they differ

Only the attributes on which Bazel and Blacksmith actually diverge.

Attributes where Bazel and Blacksmith differ
AttributeBazelBlacksmith
Pricing modelopen-sourceUnknown
PlatformsWindows, macOS, LinuxGitHub Actions, Linux, Windows, macOS

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 Bazel

  • Fast incremental builds
  • Multi-language support
  • Distributed caching
  • Parallel execution
  • Dependency analysis
  • Starlark extensibility
  • Cross-platform support

Only in Blacksmith

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

What people use each for

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

Bazel

  • Building large monorepos with hundreds of interdependent projectsnot Blacksmith
  • Multi-language projects requiring consistent build semanticsnot Blacksmith
  • Organizations requiring reproducible builds and hermetic test executionnot Blacksmith
  • Teams implementing distributed CI with shared build artifact cachingnot Blacksmith

Blacksmith

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

Where each one falls short

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

Bazel

  • Steep learning curve for developers unfamiliar with build systems
  • Initial setup complexity; requires BUILD files and Bazel configuration
  • Verbose error messages can be difficult to debug for new users
  • Smaller community and fewer third-party integrations vs enterprise tools

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

Pricing, plan by plan

Bazel

Free

No published plan breakdown. See the Bazel review.

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

Which should you pick?

Choose Bazel if

  • You need fast incremental builds.
  • You want to start without paying.
  • You work on Windows, macOS, Linux.
  • You also want multi-language support.
Bazel review

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

Questions people ask

Is Bazel or Blacksmith better?
Neither clearly leads. Bazel starts at Free and Blacksmith at Free, and user ratings are close enough to be indistinguishable. Choose on capability and platform support.
Which is cheaper, Bazel or Blacksmith?
Bazel starts at Free and Blacksmith at Free.
Does Bazel or Blacksmith run on more platforms?
Bazel runs on Windows, macOS, Linux. Blacksmith runs on GitHub Actions, Linux, Windows, macOS.
Can I use Bazel for free?
Both have a free tier, so you can try either at no cost before committing.
What is Bazel best used for?
Bazel is most often used for building large monorepos with hundreds of interdependent projects, multi-language projects requiring consistent build semantics, organizations requiring reproducible builds and hermetic test execution, teams implementing distributed ci with shared build artifact caching. Of those, building large monorepos with hundreds of interdependent projects and multi-language projects requiring consistent build semantics are not what Blacksmith is typically brought in for.
What can Bazel do that Blacksmith cannot?
Bazel covers Fast incremental builds, Multi-language support, Distributed caching, Parallel execution. Blacksmith covers Bare metal runners, Multiple OS support, ARM support, Docker layer caching.

Answered from the vendors’ own pages

Bazel: Does Bazel support distributed builds across CI infrastructure?

Yes, Bazel supports distributed execution and remote caching, allowing build work to be distributed across multiple machines and CI agents.

Source
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
Bazel: What languages can be built with Bazel?

Bazel has built-in support for Java, C++, Go, Python, and Android/iOS development, with additional language support available through custom rules and community extensions.

Source
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
Bazel: Can I use Bazel for small projects or is it only for large monorepos?

While Bazel excels at handling large projects, it can be used for smaller codebases. However, the setup overhead may not be justified for very small or simple projects.

Source
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
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