There are hundreds of pentest tools on the market and most of them are open source. That can make choosing the right tooling a long process of trial and error. These top 10 free open source tools are a good place to start if you’re looking to build your toolkit or are just wondering what’s available. 

These options aren’t a full selection. Check our Ultimate Pentest Tools list for a full list. This selection includes some of our favorites, with information on why we picked them. So, in no particular order, our top 10 open source and/or free pentest tools. 


Ncat ius something of a swiss army knife for pentesters. You need to have it. It’s a network utility for reading and writing data. It’s also a command line tool with virtually unlimited applications. 

“NCat is a go-to in my toolbox, usually I use NMap followed by NCat as part of my standard network assessment”

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Ettercap is a command-line version of wireshark, best-fit for writing filters and getting information after your basic recon is finished. It also offers sniffing, content filtering, and network/host analysis, so there’re plenty you can do with the tool. 

“Ettercap is an easy to use command line tool, you can write your filters on the go, you only get the information you actually want.” says Mike,  “That’s good if you want specific traffic details, however, if you don’t know what you’re looking for, ettercap is unusable.” 

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ReNgine is an automated recon framework for OSINT and other recon gathering. IT’s relatively new to the market (we first saw it in 2020) but it’s gone on to be an in-house favorite at Cyver. In fact, we’re using ReNgine to replace Nessus. 

ReNgine is also fully open source, and that’s a huge plus. It also manages vulnerability checking, via the front-end dashboard which supports multiple tools like Harvester. 

“It’s one platform, you only have to push one button”, says Mike Terhaar, chief pentester at Cyver and co-founder of Cyver Core, “It has the same capabilities as Nessus plus some extras. Of course, there’s a quality difference because Nessus is premium and ReNgine is open source, but I really like it. That’s especially true when you add in tool s like Harvester. You can essentially check everything as part of your web recon and have it laid out in a dashboard. The dashboard is also really good for screenshots.” 

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W3af is a web application attack and audit framework. IT’s fully open source and has been since it was launched. W3af is also friendly for ethical hackers and for internal security teams – because you can identify and exploit vulnerabilities in web applications without risking crashing the application. 

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ZAP is the world’s most widely used web app scanner for a reason. It’s free, has dozens of add-ons, and is fully integrated with OWASP. 

“When Burp doesn’t work, I always turn to ZAP” says Mike, “You need it.” 

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SQLMap is the standard injection and database takeover tool used by thousands of pentesters and ethical hackers. The tool automates SQL injection vulnerability detection. You can also set up database server takeover to fully exploit those found vulnerabilities. 

“SQLMap is also really powerful if you have a hunch SQL injection is possible. It’s flexible and much faster than doing it by hand. Very fast and easy to automate”
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Metasploit free is an open source framework for post-exploitation tool management, assessment management, and more. The Pro version costs from $15,000 per year, but thousands of pentesters use the open-source framework. 

“Metasploit needs a lot of infrastructure level data.” says Mike, “ However, it’s flexible, old-school, and makes life a lot easier if you’ve done the recon upfront.” 

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Cain and Abel

Cain and Abel is an extremely versatile password cracker for Windows with packet sniffing and MAC capabilities. With 24+ password cracking, hashing, and sniffing functions, it replaces a lot of other tools, including rainbow tables, hash calculators, and decoders. Of course, the best toolkits rely on a range of tools, but Cain and Abel is a good place to start. 

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The world’s most popular port scanner with source code available for use on the OS of your choice. It’s popular for a reason. 

“it’s obvious to have this,” says Mike, “You can’t not have it. It’s a must-have that tells you basic Ip address information, so you can figure out what’s behind it.” 

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Postman is an API development platform and it’s not entirely free. However, you can parse, test, and review API files – making it an ideal recon tool for API testing. 

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What do you think? Do these top open source/free pentest tools align with your own list? Let us know. 
“Of course,” adds Mike, “everything starts with Command Prompt, it’s magic”.