Can You Use Free or Open-Source Software and Still Pass CMMC Level 1?

Short answer: yes. CMMC Level 1 doesn't care what you paid for your software, and it doesn't care whether the code is open or closed. It cares about one thing — whether each requirement is actually met. Free tools, open-source tools, and the software already built into your computers are all fair game.

That surprises people, because "compliance" tends to sound like a reason to go buy something expensive. For Level 1, it usually isn't. But there's a real catch in the word free, and it's worth understanding before you build your setup around it.

The framework doesn't have a shopping list

There's a common assumption that being compliant means buying specific, government-blessed, or premium-branded products. CMMC Level 1 has no such list. The 15 Level 1 requirements describe outcomes — limit who can access systems, require users to log in, protect against malicious code, keep software updated, control how information is shared. They don't name vendors, and they don't set a price floor.

That means a lot of what you need, you may already own:

• A firewall — most operating systems include one built in, at no extra cost.
• Antivirus / malware protection — modern Windows ships with capable protection built in, and there are free options for other systems.
• Software updates — the automatic update features in your operating system and apps directly support the requirement to fix known flaws.
• Multi-factor authentication — many tools, including free ones, can add a second login step.

None of those carry a brand requirement. If a free or open-source tool does the job the requirement describes, it counts.

The real test isn't price — it's three questions

Whether a tool is free, open-source, or expensive, Level 1 judges it the same way. Before you rely on anything to meet a requirement, ask:

1. Does it actually do what the control asks? A free antivirus that genuinely scans and blocks malicious code meets the malware-protection requirement. A tool that's free but doesn't really perform the function doesn't — regardless of the price tag.
2. Is it kept current? Level 1 expects your malware protection to stay updated and known security flaws to get fixed. A tool only helps if it's still receiving updates and you're applying them.
3. Can you show how it's set up? Your self-assessment rests on your own documentation of how each control is met. Free tools rarely come with that paperwork, so you write it yourself.

Pass those three, and the cost of the software is beside the point.

"Free" isn't free of effort

Here's the catch. When you pay for commercial software, part of what you're buying is support, automatic updates, and sometimes documentation that helps with compliance. With free, open-source, or self-hosted tools, that work doesn't disappear — it shifts to you.

You're the one configuring it correctly. You're the one making sure it stays patched. You're the one writing down how it's set up. For a small shop with someone willing and able to do that, it's often a perfectly good trade — you spend effort instead of money. Just go in knowing that's the deal, rather than assuming "free" means "less work."

The caveat that quietly bites

The one place free and open-source tools cause real Level 1 trouble is abandonment.

Two of the Level 1 requirements are about staying current: keeping malicious-code protection updated, and identifying and correcting flaws. A tool that's no longer maintained — an open-source project that stopped shipping updates, or a free app the developer walked away from — stops getting the security fixes those requirements assume. It can sit on your systems looking fine while quietly falling out of compliance.

So if you lean on free or open-source software for a control, pick something that's actively maintained, and check now and then that it still is. A well-supported open-source project can be a great fit. An orphaned one is a liability.

The bottom line

You do not have to buy expensive software to pass CMMC Level 1. Free, open-source, and built-in tools are all allowed, and many contractors already have most of what they need sitting on machines they own.

The price tag was never the question. The question is whether each of the 15 requirements is met by something that works, stays current, and is documented — paid or not. Get that right, and a free toolkit can carry a small contractor through Level 1 just as well as a costly one.

Working out which requirements you already cover, and which still need attention, is far simpler when they're laid out plainly, one question at a time.

See exactly where you stand on CMMC Level 1.

CMMCheck walks you through every Level 1 requirement as plain-English yes / no / not-sure questions — no consultant, no jargon — and hands you a clear report showing what's done and what's left.

→ Start your Level 1 self-assessment at cmmcheck.com