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Cybersecurity · head to head

OWASP ZAP vs Userscripts

OWASP ZAP logo

OWASP ZAP

Cybersecurity

Free, open-source web application scanner and intercepting proxy, now governed by the Software Security Project.

From
Free
Rated
-
Full reviewWebsite
Userscripts logo

Userscripts

Browser Extensions

Open-source userscript manager for Safari on Mac and iOS

From
Free
Rated
-
Full reviewWebsite

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.; Userscripts safari cannot let extensions bypass a site's Content Security Policy, so strict sites produce "Refused to execute a script" errors that the @inject-into workaround does not always fix.
  • They diverge on capability: OWASP ZAP covers Intercepting proxy, Userscripts covers Built-in script editor.
  • Prices and features above were last checked on 17 September 2026.

Where they differ

Only the attributes on which OWASP ZAP and Userscripts actually diverge.

Attributes where OWASP ZAP and Userscripts differ
AttributeOWASP ZAPUserscripts
Pricing modelfreeopen-source
PlatformsDesktop, Cli, ApiSafari, macOS, iOS
CategoryCybersecurityBrowser Extensions
Founded2001Unknown

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 OWASP ZAP

  • Intercepting proxy
  • Passive scanner
  • Active scanner
  • AJAX spider
  • Automation Framework
  • Headless daemon and REST API
  • Docker images
  • Add-on marketplace

Only in Userscripts

  • Built-in script editor
  • Standard metadata support
  • GM API
  • Remote script updating
  • iCloud sync
  • Per-page popup

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 Userscripts
  • Manual penetration testing that needs an intercepting proxy, request replay and fuzzing without a paid licence per testernot Userscripts
  • Teaching developers what an attack against their own endpoint looks like, using a tool they can install themselvesnot Userscripts
  • Pre-release regression scanning of an internal application that would never justify a commercial DAST subscriptionnot Userscripts

Userscripts

  • Running userscripts on Safari without paying for Tampermonkeynot OWASP ZAP
  • Running userscripts on an iPhone or iPadnot OWASP ZAP
  • Writing scripts on a Mac and syncing them to iOSnot OWASP ZAP
  • Blocking or restyling site elements Safari content blockers cannot reachnot OWASP ZAP
  • Keeping a script library under an open-source licencenot 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.

Userscripts

  • Safari cannot let extensions bypass a site's Content Security Policy, so strict sites produce "Refused to execute a script" errors that the @inject-into workaround does not always fix.
  • Apple only. There is no Chrome, Firefox or Edge build, so it cannot be a cross-browser answer.
  • iCloud sync is documented as having delays, which is awkward when editing the same script on two devices.
  • Requires macOS 12 and Safari 14.1, or iOS 15.1, so older Apple hardware is excluded.
  • GPL v3 means a commercial licence is required for non-open-source use, which matters if you are embedding rather than just using it.

Pricing, plan by plan

OWASP ZAP

Free
  • Free & Open SourceFree
    • Full functionality
    • Active & passive scanning
    • Spider

Userscripts

Free
  • FreeFree
    • Full functionality
    • GPL v3 licensed
    • macOS, iOS and iPadOS

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.
OWASP ZAP review

Choose Userscripts if

  • You need built-in script editor.
  • You want to start without paying.
  • You work on Safari, macOS, iOS.
  • You also want standard metadata support.
Userscripts review

Questions people ask

Is OWASP ZAP or Userscripts better?
Neither clearly leads. OWASP ZAP starts at Free and Userscripts at Free, and user ratings are close enough to be indistinguishable. Choose on capability and platform support.
Which is cheaper, OWASP ZAP or Userscripts?
OWASP ZAP starts at Free and Userscripts at Free.
Does OWASP ZAP or Userscripts run on more platforms?
OWASP ZAP runs on Desktop, Cli, Api. Userscripts runs on Safari, macOS, iOS.
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 Userscripts is typically brought in for.
What can OWASP ZAP do that Userscripts cannot?
OWASP ZAP covers Intercepting proxy, Passive scanner, Active scanner, AJAX spider. Userscripts covers Built-in script editor, Standard metadata support, GM API, Remote script updating.

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.

Userscripts: Is Userscripts for Safari free?

Yes, free on the App Store and licensed under GPL v3. A commercial licence is required for use in something that is not itself open source.

Source
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.

Userscripts: Does it work on iPhone?

Yes, on iOS and iPadOS 15.1 or later, which makes it one of the few ways to run userscripts on an iPhone.

Source
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.

Userscripts: Why do I get "Refused to execute a script" errors?

Safari does not let extensions bypass a site's Content Security Policy the way other browsers do. The documented workaround is changing the script's @inject-into setting, though it does not resolve every case.

Source
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.

Userscripts: Do my scripts sync between Mac and iPhone?

Yes, over iCloud, though the project notes the sync can be delayed rather than immediate.

Source
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.

Userscripts: What are the system requirements?

macOS 12 or later with Safari 14.1 or later, or iOS and iPadOS 15.1 or later.

Source
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