Cybersecurity · head to head
OWASP ZAP vs Sigstore
OWASP ZAP
Cybersecurity
Free, open-source web application scanner and intercepting proxy, now governed by the Software Security Project.
- From
- Free
- Rated
- -
Sigstore
Cybersecurity
Free public signing and transparency infrastructure for open source artifacts
- From
- Free
- Rated
- -
The short version
- Each has a real cost: OWASP ZAP authenticated scanning of modern single-page applications is the hard part and ZAP makes you build it by hand: session handling, token refresh and login scripts are configured per application, and a misconfigured session means the scanner logs itself out and reports a clean result for pages it never reached.; 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: OWASP ZAP covers Intercepting proxy, Sigstore covers Fulcio.
- Prices and features above were last checked on 31 August 2026.
Where they differ
Only the attributes on which OWASP ZAP and Sigstore actually diverge.
Identical on both: starting price (Free), free tier (Yes), user rating (Not yet rated), category (Cybersecurity).
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 OWASP ZAP
- Intercepting proxy
- Passive scanner
- Active scanner
- AJAX spider
- Automation Framework
- Headless daemon and REST API
- Docker images
- Add-on marketplace
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.
OWASP ZAP
- Adding a baseline security scan to every application's pipeline where per-target commercial licensing would limit coverage to a handfulnot Sigstore
- Manual penetration testing that needs an intercepting proxy, request replay and fuzzing without a paid licence per testernot Sigstore
- Teaching developers what an attack against their own endpoint looks like, using a tool they can install themselvesnot Sigstore
- Pre-release regression scanning of an internal application that would never justify a commercial DAST subscriptionnot Sigstore
Sigstore
- Open source projects signing releases without running a certificate authoritynot OWASP ZAP
- Organisations meeting a signed-artifact requirement without buying a signing productnot OWASP ZAP
- Publishing provenance that a consumer can verify independently of younot OWASP ZAP
- Self-hosting the same components where a public log is unacceptablenot OWASP ZAP
Where each one falls short
Documented limitations, not opinions. Every one is a constraint you would hit in normal use.
OWASP ZAP
- Authenticated scanning of modern single-page applications is the hard part and ZAP makes you build it by hand: session handling, token refresh and login scripts are configured per application, and a misconfigured session means the scanner logs itself out and reports a clean result for pages it never reached.
- There is no support contract in the product, so when a scan breaks the day before a release the escalation path is a GitHub issue and a community chat, which is not an answer that satisfies a delivery manager or an auditor who wants a named responsible party.
- Active scanning sends genuine attack traffic, so it can create records, trigger emails, exhaust rate limits or destabilise a fragile environment, and pointing it at production without prior agreement produces an incident rather than a test result.
- Output needs triage: passive rules generate large volumes of low-severity informational findings about headers and cookie flags that bury the few results that matter, and a team without someone tuning the rule set stops reading the report within a few sprints.
- As a dynamic scanner it can only test what it can reach, so authorisation flaws between accounts, business logic abuse and anything behind an undiscovered endpoint go unreported, and a passing ZAP scan is evidence of nothing more than the absence of the classes of bug it looks for.
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
OWASP ZAP
Free- Free & Open SourceFree
- Full functionality
- Active & passive scanning
- Spider
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 OWASP ZAP if
- You need intercepting proxy.
- You want to start without paying.
- You work on Desktop, Cli, Api.
- You also want passive scanner.
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.
Questions people ask
- Is OWASP ZAP or Sigstore better?
- Neither clearly leads. OWASP ZAP 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, OWASP ZAP or Sigstore?
- OWASP ZAP starts at Free and Sigstore at Free.
- Does OWASP ZAP or Sigstore run on more platforms?
- OWASP ZAP runs on Desktop, Cli, Api. Sigstore runs on Web, Linux, macOS, Windows, Self-hosted.
- Can I use OWASP ZAP for free?
- Both have a free tier, so you can try either at no cost before committing.
- What is OWASP ZAP best used for?
- OWASP ZAP is most often used for adding a baseline security scan to every application's pipeline where per-target commercial licensing would limit coverage to a handful, manual penetration testing that needs an intercepting proxy, request replay and fuzzing without a paid licence per tester, teaching developers what an attack against their own endpoint looks like, using a tool they can install themselves, pre-release regression scanning of an internal application that would never justify a commercial dast subscription. Of those, adding a baseline security scan to every application's pipeline where per-target commercial licensing would limit coverage to a handful and manual penetration testing that needs an intercepting proxy, request replay and fuzzing without a paid licence per tester are not what Sigstore is typically brought in for.
- What can OWASP ZAP do that Sigstore cannot?
- OWASP ZAP covers Intercepting proxy, Passive scanner, Active scanner, AJAX spider. Sigstore covers Fulcio, Rekor, Keyless signing, Multi-language clients.
Answered from the vendors’ own pages
OWASP ZAP: Is it still called OWASP ZAP?
The project left OWASP in August 2024 and is now governed by the Software Security Project, with core development sponsored by Checkmarx. The tool is now just ZAP, though most existing documentation, courses and search results still use the OWASP name.
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.
OWASP ZAP: Is it free for commercial use?
Yes. It is Apache 2.0 licensed, with no per-application, per-scan or per-user cost, and it can be used and modified commercially without a licence agreement.
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.
OWASP ZAP: Can it replace a penetration test?
No. It automates checks for known vulnerability classes against endpoints it can reach. It does not reason about business logic, chain findings into an attack, or test authorisation between accounts, which is most of what a tester actually does.
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.
OWASP ZAP: Does it run in CI?
Yes, through the official Docker images and the Automation Framework, which defines scan jobs in YAML so configuration lives in the repository. A baseline passive scan is the usual starting point because it is fast and non-intrusive.
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.
OWASP ZAP: How does it compare to Burp Suite?
Burp Suite Professional is the more polished manual testing tool and has a stronger scanner and extension ecosystem, but it is licensed per tester and Burp Suite Enterprise per target. ZAP is the better fit where cost per target is the binding constraint; many teams use both.
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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