Acunetix vs Nessus: Which is right for you? [2026]

Vulnerability management has shifted significantly over the last few years. Security teams are no longer dealing with a small number of static servers protected by a network perimeter. Instead, modern environments consist of cloud workloads, containerized services, CI/CD pipelines, third-party integrations, and constantly changing web applications and APIs. This shift has expanded the attack surface and made it harder to rely on a single category of security tooling.

Two tools that frequently appear in vulnerability management evaluations are Acunetix and Nessus. While both aim to identify security weaknesses, they operate at very different layers of the stack. Nessus is widely adopted for infrastructure and host-based vulnerability scanning, whereas Acunetix focuses on dynamic application security testing for web applications and APIs.

Choosing between these tools is not simply a matter of feature checklists. It depends on where your primary risk lies, how your teams work, and whether you are securing infrastructure, applications, or both. This comparison breaks down Acunetix vs Nessus in detail and also introduces Beagle Security as an alternative automated web and API penetration testing platform for teams that need deeper, exploit-focused application security testing.

Overview of Acunetix and Nessus

Acunetix, developed by Invicti Security, is a dynamic application security testing (DAST) platform designed to identify vulnerabilities in web applications and APIs while they are running. It scans applications by crawling pages, discovering inputs, and actively testing them for vulnerabilities such as SQL injection, cross-site scripting, insecure authentication, and misconfigurations. Acunetix is particularly known for its proof-based scanning approach, which attempts to safely verify vulnerabilities to reduce false positives.

Nessus, developed by Tenable, is a commercial vulnerability scanner focused on identifying known vulnerabilities across infrastructure assets. It scans servers, operating systems, network devices, and services to detect missing patches, exposed services, insecure configurations, and known CVEs. Nessus is widely used in enterprise environments and is often part of compliance and audit-driven security programs.

While both tools are used under the broad umbrella of vulnerability management, they are designed to answer different security questions.

Acunetix vs Nessus at a glance

An alternative web and API penetration testing platform for comparison: Beagle Security

Traditional vulnerability scanners and DAST tools play an important role, but many real-world breaches exploit gaps that these tools do not fully cover. Infrastructure scanners do not understand application logic, and traditional DAST tools often struggle with complex authentication, multi-step workflows, and chained attack paths.

Beagle Security is an automated web and API penetration testing platform designed to simulate how a real attacker would attempt to exploit an application. Instead of focusing solely on vulnerability detection, Beagle Security emphasizes exploitability, attack paths, and contextual reporting.

This makes Beagle Security a complementary or alternative option for teams that want deeper application-layer coverage, especially in SaaS, API-first, and CI/CD-driven environments.

Why Beagle Security might be a better fit

Modern development teams ship code frequently, rely heavily on APIs, and implement complex authentication flows. In these environments, traditional tools often generate findings that are technically correct but difficult to prioritize or act upon.

Beagle Security may be a better fit for teams that:

• Need exploit-focused testing rather than raw vulnerability lists

• Rely on authenticated workflows and APIs

• Want findings developers can immediately understand and fix

• Integrate security testing directly into CI/CD pipelines

By focusing on real attack simulation, Beagle Security helps teams identify vulnerabilities that are most likely to be exploited in production.

Acunetix vs Nessus vs Beagle Security: Feature comparison

Acunetix web application security features

Acunetix is purpose-built for scanning web applications and APIs. It automatically crawls applications to identify pages, parameters, and endpoints before launching dynamic tests to uncover vulnerabilities.

Key capabilities include:

• Detection of OWASP Top 10 vulnerabilities

• Proof-based vulnerability validation

• Automated crawling of modern web apps

• API scanning support for REST services

• Compliance-oriented reporting

Acunetix performs well for identifying common and well-known application vulnerabilities. However, it can struggle with deeply customized business logic and multi-step attack chains that require attacker intuition.

Nessus vulnerability scanning features

Nessus focuses on identifying known vulnerabilities across infrastructure assets using a large and frequently updated plugin database.

Key capabilities include:

• Detection of CVEs across operating systems and services

• Credentialed scanning for deeper host visibility

• Configuration and compliance audits

• Broad coverage across diverse environments

Nessus excels at infrastructure hygiene and compliance readiness. Its limitation lies in its lack of visibility into application logic and runtime behavior.

Beagle Security features

Beagle Security focuses on automated penetration testing rather than passive scanning.

Key capabilities include:

• Automated attack simulation for web apps and APIs

• Support for REST and GraphQL APIs

• Advanced authentication and session handling

• Context-rich reports with exploit evidence

• Retesting workflows and CI/CD integration

This approach helps teams prioritize vulnerabilities based on real risk rather than volume.

Acunetix vs Nessus vs Beagle Security: Pricing comparison

Acunetix vs Nessus vs Beagle Security: Customer reviews comparison

Acunetix reviews

G2 rating: 4.1 / 5

Acunetix (by Invicti Security) is frequently praised for its proof-based scanning, which helps confirm exploitability and reduce false positives in web application testing. Reviewers highlight strong detection of OWASP Top 10 vulnerabilities, clear reporting, and reliable automation for DAST workflows.

Common feedback themes include:

• Accurate identification of web vulnerabilities

• Reduced false positives compared to traditional DAST

• Clean and usable reports

• Higher cost as the number of targets or scan scope increases

Nessus reviews

G2 rating: 4.5 / 5

Nessus is consistently reviewed as a reliable and mature infrastructure vulnerability scanner. Users value its extensive plugin library, regular updates, and ease of deployment across networks and hosts. It is commonly used for vulnerability management and compliance-driven scanning.

Common feedback themes include:

• Broad vulnerability and CVE coverage

• Strong credentialed scanning

• Useful compliance and audit reporting

• Asset-based licensing costs

• Limited visibility into application-layer and business-logic issues

Beagle Security reviews

G2 rating: 4.7 / 5

Beagle Security reviews often emphasize actionable, developer-friendly reporting and ease of setup for web and API penetration testing. Users highlight its ability to handle authenticated workflows, simulate real attack paths, and provide contextual evidence that helps prioritize fixes.

Common feedback themes include:

• Clear remediation guidance for developers

• Automated authenticated testing

• Strong focus on web and API security

• Improved collaboration between security and engineering teams

Acunetix vs Nessus vs Beagle Security: Which is best for you?

Choose Acunetix if:

• Your primary focus is web application vulnerability scanning

• You want proof-based validation

• You follow a traditional AppSec workflow

Choose Nessus if:

• Your priority is infrastructure vulnerability management

• Compliance and asset visibility are critical

• You need a mature enterprise scanning tool

Choose Beagle Security if:

• You need exploit-focused web and API testing

• Developer-friendly, contextual findings matter

• Continuous testing in CI/CD is a priority

Many organizations use a layered approach, combining infrastructure scanners with application-focused penetration testing.

Try Beagle Security for free to see how it compares to Acunetix and Nessus

Beagle Security provides automated penetration testing designed specifically for modern web applications and APIs, going beyond traditional vulnerability scanners that focus primarily on known signatures or infrastructure-level issues. By simulating real-world attack scenarios, Beagle helps teams identify exploitable security gaps, business logic flaws, and API-specific risks that are often missed by conventional tools.

Teams can start with a 14-day free trial, which includes full access to Beagle Security’s application and API testing capabilities. This allows security and engineering teams to run scans against real environments, review contextual findings, validate false positives quickly, and assess reporting quality before committing to a paid plan. For organizations with more complex environments or specific evaluation needs, Beagle Security also offers an interactive demo, where teams can walk through features, workflows, and integrations in detail with product experts.

This trial-and-demo approach makes it easier to directly compare Beagle Security’s accuracy, usability, and reporting clarity against tools like Acunetix and Nessus in a practical, hands-on way.

Written by

Jijith Rajan

Cyber Security Engineer

Contributor

Mayookha S Shankar

Product Marketing Specialist