# 5 Free Security Tools That Catch What Your Code Review Keeps Missing
In 2023, a SQL injection flaw in a popular library sat in production for 11 months before someone noticed. It passed code review. It passed automated scanning. The vulnerability was a single string concatenation on line 47 — and 720 million records were exposed.
That’s not an argument against code review. It’s an argument for the gaps review leaves.
Security vulnerabilities at this level aren’t sophisticated. They’re not zero-days or nation-state exploits. They’re inputs that weren’t sanitized, passwords hashed with the wrong algorithm, PII in logs that shouldn’t be there. The patterns are well-known. The problem is that catching them manually takes expertise most teams don’t have on every PR.
These five free tools don’t require accounts, subscriptions, or complex setup. They run in your browser. They catch the easy mistakes — the kind that are embarrassing to explain after a breach, not hard to fix before one.
1. Find SQL Injection Before It Finds Your Database
SQL Injection Detector checks text for dangerous query patterns. It knows what `’ OR ‘1’=’1` looks like. It flags `UNION SELECT`. It distinguishes between a quick surface scan and a full deep pattern match across stack-based, time-based, and boolean-blind injection styles.
Paste in a string, pick your scan depth, and it returns findings with line numbers. Each finding shows the matched payload and the pattern that caught it.
The critical word here is *before*. SQL injection is the #1 vulnerability in OWASP’s API top 10, and it’s still endemic because inputs look correct until they don’t. This tool is a first-pass sanity check that lives in your browser — not a replacement for parameterized queries, but the fastest way to catch the obvious mistakes before they ship.
Use it when: reviewing user-submitted content pipelines, auditing raw SQL strings in legacy code, or sanity-checking ORM output before it reaches a database.
2. Catch XSS Payloads Before They Reach Your Users
XSS Payload Detector scans input strings for cross-site scripting vectors across 10 attack categories. Script tags. Event handlers. `javascript:` protocols. URL-encoded and HTML-entity-encoded payloads. SVG-based injections. DOM-based XSS patterns like `eval` and `document.write`.
Each detection gets a severity rating: LOW, MEDIUM, HIGH, or CRITICAL. That triage is the point — you can prioritize the CRITICALs and follow up on the MEDIUMs later.
The feature that matters most: it decodes attacks before matching them. The payload `<script>` looks harmless to naive sanitizers. It doesn’t look harmless to this tool. Neither do URL-encoded `
