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Developer Tools · head to head

Blacksmith vs Sigstore

Blacksmith logo

Blacksmith

Developer Tools

2x faster GitHub Actions with 60% cost savings

From
Free
Free plan
Yes
Full reviewWebsite
Sigstore logo

Sigstore

Cybersecurity

Free public signing and transparency infrastructure for open source artifacts

From
Free
Free plan
Yes
Full reviewWebsite

The short version

  • Each has a real cost: Blacksmith per-minute pricing model requires estimating usage to predict costs; Sigstore the security model depends on somebody watching the log. The documentation states that compromise of an identity provider or of Fulcio itself is detectable only if third parties monitor the transparency log, the monitoring tool is a community-tier rather than core project, and almost no consumer runs one.
  • They diverge on capability: Blacksmith covers Bare metal runners, Sigstore covers Fulcio.
  • Prices and features above were last checked on 31 August 2026.

Where they differ

Only the attributes on which Blacksmith and Sigstore actually diverge.

Attributes where Blacksmith and Sigstore differ
AttributeBlacksmithSigstore
Pricing modelUnknownOpen source, public instance free to use
PlatformsGitHub Actions, Linux, Windows, macOSWeb, Linux, macOS, Windows, Self-hosted
CategoryDeveloper ToolsCybersecurity

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 Sigstore

  • Fulcio
  • Rekor
  • Keyless signing
  • Multi-language clients
  • Timestamp authority
  • Neutral governance

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

Sigstore

  • Open source projects signing releases without running a certificate authoritynot Blacksmith
  • Organisations meeting a signed-artifact requirement without buying a signing productnot Blacksmith
  • Publishing provenance that a consumer can verify independently of younot Blacksmith
  • Self-hosting the same components where a public log is unacceptablenot 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

Sigstore

  • The security model depends on somebody watching the log. The documentation states that compromise of an identity provider or of Fulcio itself is detectable only if third parties monitor the transparency log, the monitoring tool is a community-tier rather than core project, and almost no consumer runs one.
  • It is a 99.5 percent objective with no service level agreement, which permits several hours of downtime a month and offers no remedy. A pipeline that signs on every build has taken a hard dependency on a free service with no contract behind it.
  • Log scale is a live engineering problem rather than a theoretical one. The active shard holds billions of entries, the log has already been sharded twice, and sharding version 1 requires stopping traffic, which is why a replacement was built.
  • Ten-minute certificates make trust depend on log availability. Verifying an older signature relies on the log entry proving it was made inside that window, so a lost or unreachable entry can render a valid artifact unverifiable.
  • Migration debt is substantial and ongoing. Version 2 of the log is generally available but not the public default, the signing client has an announced breaking release ahead, some official clients lag the new log format, and a post-quantum migration is named as the next break after that.

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

Sigstore

Free
  • Public good instanceFree
    • Free to everyone with no contract
    • 99.5 percent availability objective, not an agreement
    • 100KB cap per attestation upload
  • Self-hostedFree
    • Apache-2.0
    • Run your own Fulcio and Rekor
    • Rekor v2 available for self-hosters

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 Sigstore if

  • You need fulcio.
  • You want to start without paying.
  • You work on Web, Linux, macOS, Windows, Self-hosted.
  • You also want rekor.
Sigstore review

Questions people ask

Is Blacksmith or Sigstore better?
Neither clearly leads. Blacksmith starts at Free and Sigstore at Free, and user ratings are close enough to be indistinguishable. Choose on capability and platform support.
Which is cheaper, Blacksmith or Sigstore?
Blacksmith starts at Free and Sigstore at Free.
Does Blacksmith or Sigstore run on more platforms?
Blacksmith runs on GitHub Actions, Linux, Windows, macOS. Sigstore runs on Web, Linux, macOS, Windows, Self-hosted.
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 Sigstore is typically brought in for.
What can Blacksmith do that Sigstore cannot?
Blacksmith covers Bare metal runners, Multiple OS support, ARM support, Docker layer caching. Sigstore covers Fulcio, Rekor, Keyless signing, Multi-language clients.

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
Sigstore: Is the public instance really free?

Yes, with no contract and no paid tier. That is also the weakness: a 99.5 percent objective with no agreement, no remedy and support through Slack.

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
Sigstore: Has the public log moved to Rekor v2?

No. Version 2 reached general availability in October 2025 and self-hosters can use it, but the public instance still defaults to version 1 and the project has said it will for the foreseeable future.

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
Sigstore: Does Sigstore make my dependencies safe?

No, and this is a category error worth avoiding. It tells you who published something. It has no knowledge of what the artifact contains or whether it is vulnerable.

Sigstore: What are the rate limits?

Not published. Only the 100KB cap per attestation upload is documented, so do not design a high-volume pipeline around assumed throughput.

Sigstore: Should we self-host it?

If a public record of every signature is unacceptable, or if a free service with no agreement cannot sit in your build path, then yes. Otherwise the public instance is what most projects use.

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