Developer Tools · head to head
ESLint vs OWASP ZAP
OWASP ZAP
Cybersecurity
Free, open-source web application scanner and intercepting proxy, now governed by the Software Security Project.
- From
- Free
- Free plan
- Yes
The short version
- Each has a real cost: ESLint slow performance on large codebases compared to newer tools like Oxlint and Biome; 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.
- Prices and features above were last checked on 30 August 2026.
Where they differ
Only the attributes on which ESLint and OWASP ZAP actually diverge.
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 ESLint
Nothing recorded that OWASP ZAP does not also cover.
Only in OWASP ZAP
- Intercepting proxy
- Passive scanner
- Active scanner
- AJAX spider
- Automation Framework
- Headless daemon and REST API
- Docker images
- Add-on marketplace
What people use each for
The jobs each tool is most often brought in to do.
ESLint
- Statically analysing JavaScript and JSX to find problems before runtimenot OWASP ZAP
- Automatically fixing issues with syntax-aware rewritesnot OWASP ZAP
- Enforcing a consistent code style across a teamnot OWASP ZAP
- Running as a CI step to block non-conforming codenot OWASP ZAP
- Writing custom rules for project-specific conventionsnot OWASP ZAP
OWASP ZAP
- Adding a baseline security scan to every application's pipeline where per-target commercial licensing would limit coverage to a handfulnot ESLint
- Manual penetration testing that needs an intercepting proxy, request replay and fuzzing without a paid licence per testernot ESLint
- Teaching developers what an attack against their own endpoint looks like, using a tool they can install themselvesnot ESLint
- Pre-release regression scanning of an internal application that would never justify a commercial DAST subscriptionnot ESLint
Where each one falls short
Documented limitations, not opinions. Every one is a constraint you would hit in normal use.
ESLint
- Slow performance on large codebases compared to newer tools like Oxlint and Biome
- Complexity in configuration from scratch, particularly for TypeScript support
- Limited built-in TypeScript support, requiring separate parsers and coordination with new TypeScript features
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.
Pricing, plan by plan
ESLint
FreeNo published plan breakdown. See the ESLint review.
OWASP ZAP
Free- Free & Open SourceFree
- Full functionality
- Active & passive scanning
- Spider
Which should you pick?
Choose ESLint if
- You want to start without paying.
- You work on Browser-based JavaScript, Node.js, Any JavaScript environment.
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.
Questions people ask
- Is ESLint or OWASP ZAP better?
- Neither clearly leads. ESLint starts at Free and OWASP ZAP at Free, and user ratings are close enough to be indistinguishable. Choose on capability and platform support.
- Which is cheaper, ESLint or OWASP ZAP?
- ESLint starts at Free and OWASP ZAP at Free.
- Does ESLint or OWASP ZAP run on more platforms?
- ESLint runs on Browser-based JavaScript, Node.js, Any JavaScript environment. OWASP ZAP runs on Desktop, Cli, Api.
- Can I use ESLint for free?
- Both have a free tier, so you can try either at no cost before committing.
- What is ESLint best used for?
- ESLint is most often used for statically analysing javascript and jsx to find problems before runtime, automatically fixing issues with syntax-aware rewrites, enforcing a consistent code style across a team, running as a ci step to block non-conforming code. Of those, statically analysing javascript and jsx to find problems before runtime and automatically fixing issues with syntax-aware rewrites are not what OWASP ZAP is typically brought in for.
- What can ESLint do that OWASP ZAP cannot?
- OWASP ZAP covers Intercepting proxy, Passive scanner, Active scanner, AJAX spider.
Answered from the vendors’ own pages
ESLint: Does ESLint automatically fix code issues?
Many problems ESLint finds can be automatically fixed via the --fix flag. ESLint fixes are syntax-aware so you won't experience errors introduced by traditional find-and-replace algorithms.
SourceOWASP 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.
ESLint: How much does ESLint cost?
ESLint is completely free and open-source software maintained by the OpenJS Foundation. The project accepts voluntary donations from sponsors.
SourceOWASP 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.
ESLint: Can I write custom ESLint rules?
Yes. You can develop custom rules that work alongside built-in functionality through ESLint's plugin system, allowing complete customization for your project needs.
SourceOWASP 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.
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.
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.
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