Good open-source security scanners exist, and many are excellent. That makes "we can just build it" a reasonable first thought for any engineering leader. The harder question is what it costs to run, maintain and act on those tools over time. This guide helps you compare the two paths with your own numbers.
The short answer
Building makes sense when you have a small number of repositories, a security-minded engineer with spare time, and simple needs. Buying makes sense when the work of triaging findings and producing fixes is the bottleneck, when you need reporting for customers or auditors, or when no one has time to maintain the pipeline. Most teams end up with a mix: free scanners at the core, with a paid layer where time is scarce.
What "build" really includes
Scanners are the small part. A working program also needs:
- Scanners for each need. Static analysis for your code, dependency scanning for libraries, secret detection, and perhaps container and infrastructure checks.
- A pipeline. Running scans on every pull request and on a schedule, in each repository, with caching so they are fast enough to keep.
- Rule tuning. Default rules produce noise. Someone must adjust them per language and codebase.
- Deduplication and tracking. The same issue shows up in several tools and several runs. Something must merge, track and close findings.
- Triage. Someone decides which findings are real and which matter.
- Fixes. Someone, or something, writes the change, tests it and gets it reviewed.
- Reporting. Customers, auditors and leadership each want a view of status and trends.
- Upkeep. Tools change, rules change, pipelines break.
The scanners are free. The other items are engineering time.
What "buy" really includes
A purchased platform covers part of that list, not all of it.
- It usually handles scanning, tracking, deduplication and reporting out of the box.
- Some also propose or generate fixes, which attacks the slowest step.
- You still need an owner, a process for reviewing what the platform produces, and a decision about which findings you will accept.
- You take on a vendor relationship: pricing, data handling, support and the risk of switching later.
Buying moves effort from maintaining a pipeline to managing results. It does not remove the work of deciding what to fix.
Compare the two with your own numbers
Use a simple table. Fill it in with figures from your team and finance.
| Cost line | Build | Buy |
|---|---|---|
| Initial setup | Engineer hours to integrate scanners and pipelines | Hours to connect and configure |
| Ongoing upkeep | Hours per month to tune and repair | Usually low, covered by the vendor |
| Triage | Hours per month, unaffected by the choice unless the tool reduces noise | Same, unless the product reduces noise |
| Fixing | Developer hours per fix | Developer hours per fix, possibly lower with automation |
| Reporting | Hours to build and maintain views | Included, to varying degrees |
| Licences | None for open source | Annual cost |
| Risk | Gaps in coverage when the owner leaves | Dependence on a vendor |
Multiply the hours by a loaded hourly cost from finance. Compare the yearly totals, then ask which gaps matter more to your business.
An illustration of the method, with made-up round numbers: if one engineer spends 8 hours a month on upkeep and tuning at $100 an hour, that is $9,600 a year before any triage or fixing. If a product's licence is similar in size but also removes some fixing time, the comparison shifts. Your numbers will differ. Do the arithmetic yourself.
Questions that point to building
- Do you have a small, stable set of repositories?
- Is there an engineer who wants this work and will stay?
- Are your needs met by standard scanners, with little tuning?
- Do customers and auditors accept simple reports?
- Is the cost of a licence hard to justify against the volume of findings?
If most answers are yes, start with open source and revisit when the pain grows.
Questions that point to buying
- Is the backlog growing because fixes take too long?
- Are developers ignoring findings because of noise?
- Do enterprise buyers ask for evidence you cannot produce quickly?
- Does maintaining the pipeline compete with product work?
- Do you have many repositories or several languages?
If most answers are yes, a paid layer will probably pay for itself in time. Test that claim in a trial, as described in how to run a 30-day AppSec pilot.
A middle path
Many teams keep open-source scanners for detection and pay for the parts that cost the most time:
- Aggregation and tracking of findings across tools.
- Automated fix pull requests that engineers review.
- Reporting for customers and auditors.
This keeps the option to change tools and limits what you pay for. It adds integration work, so count that too.
Mistakes to avoid
- Treating free as zero cost. Time is the cost.
- Comparing licence price to nothing. The alternative is engineering hours, not zero.
- Buying before there is an owner. A platform with nobody responsible shows a dashboard and fixes nothing.
- Building without a stopping rule. Decide how many hours you will spend before reconsidering.
- Ignoring data handling. Know what code a vendor reads, where it runs and what it keeps.
- Locking in early. Prefer terms and exports that let you leave.
What to ask a vendor
- What code is read, where is it processed, and what is retained?
- Which languages and scanners are supported, and which parts are open source?
- How are fixes produced, tested and reviewed before merge?
- What can you export if you leave?
- What does pricing do as repositories or developers grow?
- Can you run a pilot on your own code with agreed success criteria?
Frequently asked questions
Is open source less secure than a paid product? No. Many leading scanners are open source. The difference is in who maintains the pipeline and does the follow-up work.
When does the cost of building overtake buying? When upkeep, triage and fixing together use more engineer time than a licence would cost. Track hours for a month to find out.
Can we switch later? Usually yes, if you keep findings and configuration in portable formats and avoid deep lock-in.
What do enterprise customers expect? Evidence that you scan, track and fix, in a form they can read. Either path can provide it. Buying tends to make it faster to produce.
Should a very small team do anything? Yes: turn on free dependency and secret scanning in your code host, and review the results monthly.
This guide is general guidance. The worked numbers are illustrations and do not describe any company.