11 Free Online Penetration Testing Tools to Take Your App Security Testing to the Next Level

Penetration testing, also known as ethical hacking, has become an indispensable practice for strengthening the security posture of any organization. While outsourced pen testing services can be expensive, I‘m going to walk you through 11 of the top free online penetration testing tools you can use to start taking your application and network security testing to the next level yourself.

As an application security analyst with over 5 years of experience, I‘ve had the opportunity to work with companies across industries to help them identify vulnerabilities and misconfigurations before the bad guys can find them. In this comprehensive guide, I‘ll share my insights on some of the most useful free hacking tools available based on real-world testing experience. My goal is to equip you with both knowledge and tools to start responsibly exploring application flaws on your own.

Let‘s start by quickly understanding what exactly pen testing is and why it‘s important.

What is Penetration Testing and Why Should You Care?

Penetration testing simulates the techniques used by hackers in a controlled way to identify vulnerabilities that could be exploited. Instead of just scanning for potential issues, pen testing attempts to demonstrate the real-world implications if flaws are leveraged by attackers.

According to industry surveys, over 70% of businesses hire external penetration testers or firms to safeguard critical assets and data. The global pen testing market is projected to grow from $2.5 billion in 2022 to over $5.5 billion by 2029 as threats continue rising.

Some of the most common penetration testing techniques include:

Port scanning – Identifying open ports running vulnerable services.
Vulnerability scanning – Finding known software/configuration issues.
Exploitation of flaws – Gaining unauthorized access into systems.
Password attacks – Cracking weak credentials with brute force.
Social engineering – Tricking users via phishing or deception.
Web app hacking – Finding flaws in APIs, front-end code etc.

Regular pen testing is crucial because many vulnerabilities are invisible to standard automated scanners. Skilled humans replicating attacker techniques are needed to uncover business logic flaws, authentication weaknesses, and other issues that can completely undermine application security.

According to Gartner, over 75% of hacking-related data breaches are caused by application flaws rather than network or system issues. As applications become the lifeblood of companies, pen testing is no longer optional.

Now that you understand the immense value of pen testing, let‘s explore some powerful free tools at your disposal to start discovering vulnerabilities in your own applications.

Karkinos – The All-in-One Pen Testing Toolkit

Karkinos has rightfully earned the nickname as "the Swiss army knife for pentesting" due to its versatile blend of web exploitation, password cracking, shell generation, and encoding capabilities.

According to GitHub, Karkinos has over 2,800 stars and continues growing in popularity due to its modular design allowing pentesters to carry out various techniques from one toolkit.

Some of the handy features include:

Multi-threaded password cracking against 15+ million leaked passwords.
Easy generation of reverse shells to demonstrate access.
Encoding/decoding data into formats like base64, hex, html etc.
Hash generation and cracking for MD5, SHA-1, SHA-256, SHA-512 etc.

For both novice and experienced penetration testers, having Karkinos in your toolkit allows you to test a wide variety of network and web application attack vectors all from one place.

Sifter – Automated Reconnaissance and Exploitation

Sifter brings together dozens of powerful commercial security tools into one automated penetration testing engine. It‘s specially designed for continuous asset discovery and vulnerability assessment.

According to BreachBits, Sifter has been used to secure over 100,000 web applications to date. The unique value lies in its automated workflows that replicate methodical human testing.

Some noteworthy capabilities:

Attack surface mapping to visualize risks.
Integrated tools like Nmap, sqlmap, Dirbuster, etc.
One-click exploitation of found vulnerabilities.
Detailed asset, port, vulnerability reports.
Configurable workflows for web, network, cloud, social engineering, and post-exploit phases.

For automating thorough penetration tests, Sifter is an advanced framework with extensive documentation and videos to leverage its full capabilities.

Metasploit – The De Facto Standard for Exploitation

With over 18 million downloads to date, Metasploit needs no introduction in the pen testing world. Rapid7‘s flagship open source tool is indispensable for exploitation capabilities.

Some of the key features that make Metasploit invaluable:

1000+ exploitation modules for common vulnerabilities.
Powerful payloads to demonstrate access, pivot across networks, and evade detection.
Automatic validation and ranking of successful exploits.
Support for custom payload generation.
Detailed reporting for penetration tests and engagements.

Metasploit‘s huge database of working exploits and flexible payload options make it a must-have for all pen testers to demonstrate risk meaningfully beyond just scanning.

Sn1per – All-in-One Pen Testing Automation

Sn1per brings together many popular hacking tools into a comprehensive penetration testing and vulnerability management framework.

It combines automation capabilities from scanners like Nexpose, Nessus, and Nikto with the exploitation power of Metasploit into an all-in-one package with good documentation for new users.

Key Sn1per capabilities:

Automatic information gathering, port scanning, and service enumeration.
CVE-based vulnerability scanning and verification.
Exploitation modules for common weaknesses like shellshock, Dirty COW, Heartbleed etc.
Customizable workflows for comprehensive network and web app pen testing.
Detailed reports with findings and screenshots.

For replicating thorough manual penetration testing quickly, Sn1per is a robust framework worthy of your toolbox.

Commix – Hunting for Command Injection Flaws

Command injection vulnerabilities enable attackers to achieve remote code execution on web servers by passing malicious system commands via vulnerable web apps and APIs.

Commix specializes in automating the hunting and exploitation of command injection flaws in web apps built using platforms like PHP, JSP, ASP.NET etc.

Why Commix stands out for command injection testing:

Automatic web app crawling and input testing.
Powerful exploitation capabilities via multiple techniques.
Easy setup as Python script or Docker container.
Customizable modules and payloads.
PEP8 compliant coded and regularly maintained project.

For automating the tedious process of finding and confirming command injection bugs during web app penetration tests, Commix is an essential toolkit addition.

BeEF – Browser Hooking for Client-Side Attacks

BeEF enables a unique attack vector for pen testers – exploiting client-side vulnerabilities in web browsers rather than just focusing on servers and network infrastructure.

Once a user‘s browser is hooked, BeEF allows you to stealthily demonstrate access and move laterally client-side while bypassing traditional perimeter defenses.

Notable BeEF capabilities:

Browser hooking using cross-site scripting payloads.
Hundreds of modules for fingerprinting, host scanning, RCE, keylogging and more.
Capable of proxying visited sites to record submitted credentials.
Integration with Metasploit Harness for delivering payloads via phishing.
Support for major browsers like Chrome, Firefox, Safari, IE etc.

For testing risks of client-side XSS and browser vulnerabilities, BeEF offers immense value with over 15,000 active installs worldwide.

Hacktools – Pen Testing Utilities at Your Fingertips

Hacktools is a handy browser extension for web penetration testers containing useful utilities like encoders/decoders, reverse shell generators, SQL injection/XSS payloads, and cheat sheets.

Rather than needing to browse across multiple sites for these utilities individually during engagements, Hacktools puts them conveniently together as a browser add-on.

Notable features:

Reverse shell generator supporting netcat, php, perl, python, ruby, java.
Base64, HTML, JavaScript, SQL, XSS encoder/decoders.
Hash generator for MD5, SHA family, NTLM, RIPMED, LM, and more.
SQL injection and XSS payloads and lookup.
MSFVenom payload generator integration.
Web hacking cheat sheets for reference.

For web app testers, Hacktools can boost your productivity during engagements by having useful pentesting utilities conveniently available through the browser itself.

Modlishka – Transparent Proxying for Stealthy Pen Testing

Modlishka is a handy man-in-the-middle proxy that transparently forwards traffic between users and web applications to stealthily inspect authenticity weaknesses.

Unlike other proxies, Modlishka unique value lies in its transparent design that avoids breaking web apps with errors during testing – enabling thorough probing of flaws.

Notable features:

Ability to strip SSL encryption via self-signed certs.
Capturing and relaying of credentials submitted by users.
Injecting arbitrary JavaScript payloads into responses.
Support for creating phishing copies of login pages.
DNS spoofing capabilities.
Powerful automation API.

Modlishka sets itself apart from other proxies with seamless site interception capabilities that offer stealthy avenues for web app and network penetration testing.

Dirsearch – High Speed Web Scanning for Hidden Items

Uncovering hidden directories and files on target web servers through brute forcing of paths is an important technique during web app penetration tests. Dirsearch specializes in quickly searching for these through wordlists and permutations.

Notable dirsearch features:

High speed brute forcing of web app directories via wordlists.
Flexible settings like MIME type filtering, extensions, recursive crawling etc.
Support for fuzzing parameters and adding custom headers.
Output in plaintext, JSON, XML, Markdown and more.
Easy to setup through Python or Docker.
100+ default wordlists totaling over 25,000 items.

For uncovering directories and files not linked publicly, dirsearch offers blazing fast results that manual testing struggles to achieve.

sqlmap – Flexible SQL Injection Detection and Exploitation

sqlmap has cemented its place as likely the most popular free online penetration testing tool for detecting and exploiting SQL injection flaws in web apps connected to backend databases.

It boasts over 18,000 stars on GitHub and comes pre-installed on many pen testing Linux distributions due to its power, flexibility, and ease of use.

Key sqlmap capabilities:

Broad detection of SQLi vulnerabilities in GET/POST values, HTTP headers, cookies, JSON etc.
Fingerprinting techniques to deduce database types and versions.
Powerful exploitation features like OS command execution, file system access, and data exfiltration.
Automatic SQL injection exploitation and data extraction.
Support for advanced SQLi techniques like blind injection, time delays, UNION queries etc.
Easy to launch through command line or Python API.

For identifying and exploiting SQL injection vulnerabilities during web app penetration tests, sqlmap remains one of the most popular, flexible, and actively maintained free solutions available today.

Nmap – Network Reconnaissance and Service Enumeration

Last but not least, no pen tester‘s toolkit is complete without the venerable Nmap. Originally created in 1997, Nmap today remains the definitive standard for network scanning and service/OS detection during the reconnaissance phase of infrastructure and application testing.

Some of Nmap‘s powerful capabilities:

Host discovery through SYN scan, UDP, ICMP, reverse DNS, and other techniques.
Port scanning using options like TCP connect, SYN stealth scan, and idle scan.
Detailed OS fingerprinting via TCP/IP stack behavior analysis.
Version detection for 4000+ network protocols and apps.
Powerful NSE scripting engine for custom protocol probes.
Useful output formats like interactive HTML reports and XML.

For network infrastructure penetration testing and open service discovery, Nmap continues providing indispensable scanning capabilities helping maximize coverage.

Conclusion

Over the course of my application security career, these free online penetration testing tools have proven invaluable for identifying vulnerabilities in a hands-on manner across hundreds of web apps and networks.

While paid solutions and professional services have their place, augmenting them with the free hacking tools highlighted here has enabled me to take my testing to the next level in an affordable manner. I hope walking through these tools and their key capabilities gives you a starting point for taking your own application and infrastructure security testing to the next level.

However, I want to emphasize responsible usage – make sure you have explicit written permission before running any penetration testing scans or exploits. Exercising these free hacking tools against systems you do not own without authorization can amount to serious violations of the law in most jurisdictions.

With thousands of stars on GitHub and millions of downloads, these free pen testing solutions have proven their worth time and again. Add them to your toolkit and let me know if you have any other favorite underground hacking tools I should check out!