Closed-source software refers to programs whose source code isn’t shared with the public. You can use the app, but you can’t peek “under the hood” to see how it works or make changes.
If you’ve ever wondered what makes a program “closed source,” why it matters for cybersecurity, and how to spot risks and benefits, you’re in the right spot. We’ll break it all down with real-world examples, analogies, and some pro-level best practices—for everyone from cybersecurity newcomers to seasoned pros.
What is closed-source software?
Closed-source software is software whose creators don’t release the program’s original instructions (called the “source code”) to the public. This means only authorized people (usually the software company’s employees and partners) can see, change, or share the code that makes the app run.
Anyone can buy, download, or use “closed source” software—but you won’t get access to what’s inside it or the ability to change how it works. Big names like Microsoft Office, Adobe Photoshop, and macOS fall into this category.
How is closed-source software different from open-source software?
Simply put, it’s open. It comes down to transparency and control.
Closed source: Source code is hidden. Only the company or its partners can view or modify it. You can install and use the app, but that’s it.
Open source: Source code is shared publicly. Anyone can look at it, change it, or even help improve and redistribute it (as long as they follow some licensing rules).
Analogy time: Think of closed source like buying a car with the hood welded shut. You can drive it, but can’t tinker with the engine. Open source? That’s a car with a wide-open hood and a manual, free for you (and your friends) to fix, modify, or upgrade.
What are the features and examples of closed-source software?
Closed-source software is everywhere. Some hallmarks:
Proprietary licensing: You pay for a license to use the software, not “own” it fully.
Updates and support: The company controls updates, bug fixes, and new features.
Limited customization: Customizing or expanding the program is usually a no-go (unless you have a special contract).
Legal restrictions: Reverse engineering or copying the software is restricted or outright illegal.
Everyday examples include:
Microsoft Office suite (Word, Excel, PowerPoint)
macOS and Windows operating systems
Adobe Creative Cloud (Photoshop, Illustrator)
Zoom, Slack, and most major antivirus programs
Why do companies use closed-source software?
There are a few big reasons organizations keep their code under wraps:
Business interests: Protect intellectual property (IP), keep competitors from copying features or designs.
Consistent user experience: Companies maintain full control over updates, ensuring things work as intended.
Monetization: Closed-source software is often sold or licensed, making it easier to generate revenue.
Security (with a caveat): By hiding the source code, it’s believed to be less vulnerable to attack, but that’s not always the case. (More on this below!)
How does closed-source software impact cybersecurity?
The cybersecurity stakes are high for all software, but closed-source comes with unique factors. Here’s the lowdown:
Pros of closed-source software for security
Attack surface is hidden: If attackers can’t see the source code, it’s (slightly) harder to spot vulnerabilities.
Controlled patching: The company has tight control over security updates, reducing “wild west” risk from haphazard third-party changes.
Professional support: Most closed-source vendors offer dedicated security teams and customer support.
Cons of closed-source software for security
Lack of transparency: Security researchers and defenders can’t easily audit how things work under the hood, so vulnerabilities might stay hidden for longer.
Slow response to vulnerabilities: You're at the mercy of the vendor’s patching schedule.
Risk of “security by obscurity”: Relying solely on hidden code for protection is weak; determined attackers can still reverse engineer apps.
Case in point: The infamous WannaCry ransomware used a vulnerability in closed-source Windows software. Because the code was hidden, many organizations didn’t know about the bug until after hackers did.
Best practices for using closed-source software
Keep your devices and organization safe using these practical steps:
Update promptly: Always install patches and updates as soon as they’re available.
Understand vendor policies: Know how your vendor handles vulnerability disclosures, patch development, and support timelines.
Supplement with open source: Where possible, use open source alternatives for tasks that require more transparency.
Audit permissions: Limit software privileges to the minimum necessary for daily tasks.
Stay informed: Sign up for cybersecurity advisories that mention new vulnerabilities in the closed-source tools you use (US-CERT is a great start).
Top five FAQs about closed-source software
Not always. Security depends on how well the code is written, tested, and updated, not just on whether the code is hidden. Closed source can hide flaws from casual observers, but determined attackers may still find them. Strong vendor support is key.
Usually no. Most closed-source licenses legally prevent you from changing, studying, or sharing the software, even if you’re a technical pro.
Closed-source software usually comes with a proprietary license or “terms of use” document that makes it clear you can’t access or modify the code. You won’t find a public GitHub or Bitbucket repository with the code, either.
Nearly always, no. Most licenses, as well as copyright law, say you can’t decompile, reverse engineer, or analyze the code without explicit permission. There are some exceptions for interoperability under specific laws, but tread carefully.
There’s no universal answer. Open source is great for transparency and community support. Closed source offers dedicated support and a consistent user experience. The best choice depends on your security needs, compliance standards, and technical resources.
Key takeaways
Closed-source software is a staple of the digital world, powering everything from personal laptops to massive enterprise networks. While you don’t get to peek at (or hack) the code, you do get structure, support, and a consistent experience.
Security isn’t about hiding your code; it’s about keeping your software well-maintained and informed. If you use closed-source tools, stay vigilant with updates, policy reviews, and basic cybersecurity hygiene. Mix in open-source options where transparency matters.
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