Burp Suite and OWASP ZAP are both intercepting proxies for analyzing, modifying and automating the HTTP requests of a web app during a security assessment. Burp Suite focuses on a highly polished operator experience and fast workflows for manual testing, while OWASP ZAP offers an open source platform with a built-in scanner, an API and automation available at no license cost.

The choice doesn't come down to which scanner finds more vulnerabilities. In a real assessment, what matters is the quality of the proxy, how quickly you can repeat a request, how authentication is handled, control over scope, and the time it takes to verify false positives. A scanner that produces a lot of unvalidated findings can slow the work down more than it speeds it up.

This article compares the two tools using the same operational sequence:

  1. proxy and browser configuration;
  2. crawling and endpoint discovery;
  3. analysis of authenticated requests;
  4. modifying and replaying with Repeater or Request Editor;
  5. passive and active scanning;
  6. automation, extensions and results management.

Tests should only be run against applications you own or environments you're explicitly authorized to test. For a reproducible lab you can use OWASP Juice Shop, WebGoat or PortSwigger Web Security Academy.

Table of contents

Main differences

Both tools sit between the browser and the application. The browser sends a request to the local proxy, the proxy displays it and can forward it to the server after modifying it. The same request can then be saved, repeated and turned into a test case.

Area Burp Suite OWASP ZAP
Proxy Stable proxy, very polished interface and excellent traffic control tools Full-featured proxy, integrated with HUD and scan contexts
Manual replay Repeater is fast and well suited to iterative testing Request Editor and resend are available, with a workflow less focused on replay
Scanner Passive Scanner in the free editions; active scanning in the paid editions Passive and Active Scanner included in the platform
Automation API, headless scanner and integrations mostly in the professional editions API, Automation Framework and CI/CD pipeline integration
Extensions BApp Store and Montoya API for Java extensions Marketplace, add-ons and Java, Python and script APIs
Results management Effective issue definitions and project organization Configurable Alert, Risk and Confidence filters
License Free Community edition with operational limitations; paid Professional and Enterprise editions Open source and free, with optional commercial support

Burp Suite tends to be faster for manual work. ZAP offers an automation surface that's easier to adopt in a project that needs to run from a script or a pipeline. This distinction matters more than an abstract comparison between the two scanners.

Burp Suite: operational workflow

Configuring the proxy

After starting Burp Suite, the proxy is normally exposed on 127.0.0.1:8080. You can use Burp's built-in browser or manually configure Firefox or Chromium.

Manual configuration also requires installing the CA certificate generated by Burp, needed to inspect HTTPS traffic without certificate errors in the browser. The certificate should only be installed in the test environment, never in a profile used for everyday browsing.

In the Proxy > Intercept panel, interception can be turned on or off. During the exploration phase it's better to leave it off and watch traffic in HTTP history instead. Continuously intercepting every request makes browsing slow and adds noise.

The Proxy > Settings function lets you configure scope, interception rules and WebSocket request handling. Limiting scope to the application's domain right away avoids capturing external traffic like analytics, CDNs or third-party services.

Collecting endpoints and application surface

The browser is used to manually walk through the application's main functions: login, search, profile editing, upload, API calls and logout. Every observed request shows up in the history and can be added to the site map.

Manual navigation stays useful even when you have an automated scanner available. Modern JavaScript-built applications may only load certain endpoints after an interaction, while a generic crawler might not reach menus, modals or flows gated behind client-side state.

To include a request in the test, just check host, port and protocol in the history. From there you can send selected items to Repeater, Intruder or Organizer. Extensions installed from the BApp Store can add analysis for JWT, GraphQL, OpenAPI and other formats.

Analyzing authentication

Burp keeps track of cookies, headers and tokens observed during navigation. An authenticated request can be sent to Repeater to check behavior with a different user, an expired token or a missing authorization parameter.

The check needs to distinguish authentication from authorization. Removing the cookie and verifying a redirect to login tests the former. Swapping a resource identifier for one belonging to another account tests access control instead.

For complex flows, Burp Professional offers session handling features that can refresh tokens and cookies before sending a request. The configuration needs care: a badly recorded macro can refresh the wrong session or produce results that look valid but aren't reproducible.

Repeating and modifying requests

The move from HTTP history to Repeater is one of Burp's strong points. The request stays available in a dedicated tab, where you can edit method, path, query string, headers and body. Sending it shows status code, size, timing and the full response.

A simple test on a JSON endpoint might start from a request like this:

POST /api/profile HTTP/1.1
Host: app.test
Content-Type: application/json
Authorization: Bearer <token>

{"displayName":"Alice"}

In Repeater you can change the field, remove the Authorization header, add unexpected parameters or alter the HTTP method. Comparing responses is helped by the built-in diff function, useful when the server returns nearly identical pages with a single meaningful difference.

Intruder is well suited to parameterized tests on a single point of the request. The Community Edition throttles attack speed, while the paid editions remove that limit. For most manual checks, though, Repeater stays easier to control and produces less noise.

Running a scan

Burp's Passive Scanner analyzes observed traffic without sending additional requests. It can flag cookies missing attributes, missing headers, mixed content and other issues detectable from the response alone.

Active scanning is available in the professional editions. Before starting it you need to define scope, exclude destructive endpoints and consider how features that modify data will behave. Running active scan indiscriminately against a shared environment is bad practice, regardless of how good the tool is.

Results include a description, a sample request, a response and a confidence indication. A finding needs to be validated with Repeater: the scanner's report is a starting point, not conclusive proof of a vulnerability.

OWASP ZAP: operational workflow

Configuring the proxy

ZAP also commonly uses 127.0.0.1:8080 by default. The browser can be launched directly from ZAP's interface, or configured to use the proxy and the local CA certificate.

The interface shows traffic in the Sites tree nodes. The History panel lets you filter requests and responses, while the HUD tab can overlay controls and information directly on the browser page. HUD is handy for quickly checking session state, but it can get in the way during a detailed analysis.

ZAP organizes work through Contexts. A context groups URLs, authentication, users and inclusion or exclusion rules. Setting it up at the start helps the scanner tell the target application apart from external resources.

Collecting endpoints and application surface

Manual navigation populates the Sites tree with pages, APIs, parameters and responses. ZAP can also use the traditional spider or the AJAX Spider to follow applications with a more complex JavaScript component.

The traditional spider works well with HTML links and predictable paths. The AJAX Spider uses a browser to run JavaScript and reach elements generated client-side, but it can take more time and needs local dependencies.

When the application exposes an OpenAPI spec, it can be imported to build a more complete test surface. That's preferable to random endpoint discovery: the document describes methods, parameters and schemas that the crawler might otherwise miss.

Handling login and users

ZAP supports sessions, contexts and users defined for scanning. The Session Properties panel lets you set the session management method, while context properties can include the login URL and the data needed for authentication.

An assessment with two users needs an explicit configuration. Requests must be tied to the right user, and the application needs to be monitored to make sure the token gets refreshed without breaking the scan.

Automatic login configuration isn't always enough for applications with MFA, CAPTCHA or dynamic challenges. In those cases it's often more reliable to log in through the browser, confirm ZAP has captured the session, and then use the recorded requests as the basis for manual tests.

Modifying and repeating requests

A request from the History panel can be opened with Open/Resend with Request Editor. The editor lets you change the HTTP message and send it again, showing the response, status code and headers.

Reusing the earlier example, the test can be run like this:

POST /api/profile HTTP/1.1
Host: app.test
Content-Type: application/json
Authorization: Bearer <token>

{"displayName":"Alice"}

You can modify the body, remove the token, or swap out the value of an identifier. ZAP also lets you add the request to a comparison session and use scripts to automatically transform messages before sending.

Compared to Repeater, Request Editor needs a few more steps for a very fast edit-and-send cycle. In exchange, its integration with scripts opens up interesting possibilities for anyone who wants to build repeatable checks.

Running a scan

ZAP includes both a Passive Scanner and an Active Scanner. The first analyzes traffic already observed, while the second sends additional payloads to selected endpoints.

The Scan Policy Manager lets you choose which plugins to enable and at what aggressiveness level. Tuning it matters: a full scan can generate a large number of requests and alerts, especially against APIs with many parameters.

An example of launching a scan from the command line with Docker:

docker run --rm -t \
  -v "$PWD/reports:/zap/wrk:rw" \
  ghcr.io/zaproxy/zaproxy:stable \
  zap-baseline.py \
  -t https://app.test \
  -r baseline.html

zap-baseline.py runs a passive scan and a limited crawl, producing a report. It doesn't replace an active scan or manual validation. In a CI pipeline, the severity level that fails the job should be a deliberate project decision, not an accepted default.

Scanners and false positives

Scanners work by heuristics. A cookie without HttpOnly can be intentional for a session managed by JavaScript, while a missing header may be irrelevant if the context doesn't call for it. An automated result should always be tied back to a concrete impact.

Finding Manual verification
Cookie without Secure check whether the cookie is transmitted over HTTPS and whether reachable HTTP paths exist
Missing security header verify actual browser behavior and the type of content served
Reflected input check the output context and whether code execution is possible
Suspicious access control repeat the request with a second user and compare status, body and side effects
Permissive CORS test origin, credentials and the data actually returned
SQL error or response anomalies reproduce the behavior with controlled input and assess any data access

Burp tends to present results with a flow more geared toward manual triage and report writing. ZAP typically separates Risk and Confidence, a useful distinction for not treating a low-confidence alert as a confirmed vulnerability.

In both cases it's worth recording four things: the original request, the change applied, the response observed, and the impact. A finding without that trail is hard to verify and even harder to fix.

Automation and extensions

ZAP has a clear edge in accessible automation. Its API can be used to start the spider, the scanner and result collection. The Automation Framework lets you describe the work plan in a YAML file, making behavior more reproducible across environments.

Burp offers automation through its API and headless tools, mostly in the professional editions. BApp Store extensions expand the product with features for JWT, authorization, logging, GraphQL and custom analysis. The ecosystem is very practical, but the availability of some features depends on the license.

For custom extensions, Burp now uses the Montoya API, while ZAP supports add-ons and scripts in several languages. An extension should add a specific check or cut down on repetitive work. Installing a lot of add-ons without evaluating their maintenance and permissions makes the environment less predictable.

A concrete example is testing authorization across multiple objects. A script can extract an identifier from the response, substitute it in the next request, and compare the result with the one obtained by the authorized user. This kind of check requires application logic that a generalist scanner can't reliably infer on its own.

Cost and choosing the tool

OWASP ZAP is open source and can be used without buying a license. That makes it suitable for labs, teaching projects, teams building internal pipelines, and assessments where the tooling budget is limited.

Burp Suite Community Edition is enough for the proxy, history and a good chunk of manual testing. The most significant limitations concern speed and the availability of advanced features, including active scanning and some automation capabilities. Burp Suite Professional adds the scanner, Intruder without the Community Edition's speed limit, project features and dedicated integrations.

Pricing and commercial models can change, so the financial evaluation should be based on the product's official page and the license that applies to your team. The cost of the license should be weighed against the time saved on replay, triage and reporting, not just the number of features listed.

A practical rule of thumb:

  • Burp Suite for intensive manual assessments, fast request debugging and very frequent individual workflows;
  • OWASP ZAP for automation, CI/CD integration and work that has to stay entirely open source;
  • both, for cross-validation, when a project needs both a fast manual flow and an independent automated scan.

An effective process can start with ZAP in a baseline pipeline, to catch regressions in headers, cookies and obvious misconfigurations on every application change. Findings above a meaningful severity threshold should be filtered and sent to the team only after minimal verification.

Manual analysis can then move to Burp Suite, especially for testing authorization, parameter manipulation, business logic and flows that depend on multiple requests. Repeater and the history make it straightforward to build a series of controlled test cases.

Using both together shouldn't turn into mechanical duplication. Running the same active scan with identical settings on both tools rarely doubles coverage. It's more valuable to use the second tool to check different endpoints, reproduce a finding, or verify an uncertain result with a different technique.

The repeatable sequence stays the same: define scope, record the authenticated flow, collect endpoints, manually repeat sensitive requests, run a passive scan, run an active scan against a controlled environment, and validate every alert. The final report should separate confirmed vulnerabilities, informational observations and closed false positives.

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