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Cybersecurity · head to head

Sigstore vs Spacelift

Sigstore logo

Sigstore

Cybersecurity

Free public signing and transparency infrastructure for open source artifacts

From
Free
Free plan
Yes
Full reviewWebsite
Spacelift logo

Spacelift

Developer Tools

Infrastructure-as-code orchestration for Terraform, OpenTofu, Pulumi and Kubernetes

From
Free
Free plan
Yes
Full reviewWebsite

The short version

  • Each has a real cost: 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.; Spacelift users are unlimited and private workers are metered, so deployment concurrency rather than headcount drives the bill, which inverts how most engineering budgets are built and is easy to under-forecast.
  • They diverge on capability: Sigstore covers Fulcio, Spacelift covers Multi-tool orchestration.
  • Prices and features above were last checked on 31 August 2026.

Where they differ

Only the attributes on which Sigstore and Spacelift actually diverge.

Attributes where Sigstore and Spacelift differ
AttributeSigstoreSpacelift
Pricing modelOpen source, public instance free to useBy private worker and tier, not by user
PlatformsWeb, Linux, macOS, Windows, Self-hostedWeb, Self-hosted, Cloud
CategoryCybersecurityDeveloper Tools

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 Sigstore

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

Only in Spacelift

  • Multi-tool orchestration
  • Policy as code
  • Private workers
  • Spaces
  • Blueprints
  • Drift detection

What people use each for

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

Sigstore

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

Spacelift

  • Platform teams running infrastructure changes through approval gates rather than through application CInot Sigstore
  • Organisations standardising Terraform and OpenTofu across many teams with policy enforcementnot Sigstore
  • Estates needing private runners so cloud credentials never leave the networknot Sigstore
  • Teams wanting drift detection and reconciliation rather than plan-time checks alonenot Sigstore

Where each one falls short

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

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.

Spacelift

  • Users are unlimited and private workers are metered, so deployment concurrency rather than headcount drives the bill, which inverts how most engineering budgets are built and is easy to under-forecast.
  • There is no affordable paid entry point. The free tier stops at two users and the next tier is a five-figure commitment with nothing in between.
  • Three of the five tiers are quote-only, so a shortlist cannot be costed without entering a sales process with each vendor on it.
  • The self-hosted build lags the hosted one, has no public worker pool and lacks the Azure and Google Cloud integrations available in the SaaS product, with OIDC federation offered as the workaround.
  • Stacks, Rego policies, Blueprints, Spaces and Spacelift-managed state are proprietary constructs, so leaving means rebuilding the orchestration layer rather than pointing it at a different runner.

Pricing, plan by plan

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

Spacelift

Free
  • FreeFree
    • Two users
    • Public workers only
    • No private workers
  • Starter Plus$undefined/year
    • Unlimited users
    • Two public workers
    • One to two private workers
  • Business$undefined/year
    • Unlimited users
    • Three private workers
    • Quoted
  • Enterprise$undefined/year
    • Unlimited users
    • Five to thirty private workers
    • Self-hosted option

Which should you pick?

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

Choose Spacelift if

  • You need multi-tool orchestration.
  • You want to start without paying.
  • You work on Web, Self-hosted, Cloud.
  • You also want policy as code.
Spacelift review

Questions people ask

Is Sigstore or Spacelift better?
Neither clearly leads. Sigstore starts at Free and Spacelift at Free, and user ratings are close enough to be indistinguishable. Choose on capability and platform support.
Which is cheaper, Sigstore or Spacelift?
Sigstore starts at Free and Spacelift at Free.
Does Sigstore or Spacelift run on more platforms?
Sigstore runs on Web, Linux, macOS, Windows, Self-hosted. Spacelift runs on Web, Self-hosted, Cloud.
Can I use Sigstore for free?
Both have a free tier, so you can try either at no cost before committing.
What is Sigstore best used for?
Sigstore is most often used for open source projects signing releases without running a certificate authority, organisations meeting a signed-artifact requirement without buying a signing product, publishing provenance that a consumer can verify independently of you, self-hosting the same components where a public log is unacceptable. Of those, open source projects signing releases without running a certificate authority and organisations meeting a signed-artifact requirement without buying a signing product are not what Spacelift is typically brought in for.
What can Sigstore do that Spacelift cannot?
Sigstore covers Fulcio, Rekor, Keyless signing, Multi-language clients. Spacelift covers Multi-tool orchestration, Policy as code, Private workers, Spaces.

Answered from the vendors’ own pages

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.

Spacelift: How is Spacelift priced?

By tier and by private worker count rather than per user. Users are unlimited on every paid plan. The published figure on the pricing page carries no period label, and the FAQ describes the tier as an annual subscription, so confirm the period in writing.

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.

Spacelift: Does it support OpenTofu?

Yes, and Spacelift sponsors the OpenTofu project, which is a substantive hedge for anyone avoiding Terraform under the Business Source Licence.

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.

Spacelift: Is there a self-hosted version?

Yes, described as carrying Enterprise functionality, but it is priced on request and lags the hosted product on cloud integrations.

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.

Spacelift: Why not just use the CI system we already have?

That is the real comparison. General purpose CI handles state, drift, approval gates and concurrency control for infrastructure poorly, and whether that is worth a five-figure floor depends on how much infrastructure change your organisation actually ships.

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.

Spacelift: What happens to our pipelines if we leave?

They do not port. Rego policies, Blueprints, Spaces and managed state are Spacelift constructs and the orchestration has to be rebuilt elsewhere.

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