Check My Links: The Browser Extension Every Bug Bounty Hunter, Pentester, and OSINT Analyst Should Know About
Imagine you're investigating a company's public-facing infrastructure during a bug bounty engagement. The target website appears modern and secure. Every visible page looks updated, and there are no obvious vulnerabilities.
Then you run a simple browser extension called Check My Links.
Within seconds, dozens of broken links appear across the website. Some point to old subdomains, retired applications, forgotten admin portals, and archived resources that nobody remembered existed. One abandoned URL leads to an outdated legacy application running vulnerable software.
This scenario is more common than many organizations realize.
In modern cybersecurity investigations, broken links are often more than just SEO problems. They can reveal forgotten assets, hidden infrastructure, legacy applications, misconfigured redirects, and even potential attack surfaces that attackers actively search for.
Check My Links is a lightweight browser extension designed primarily for link validation, but cybersecurity professionals frequently use it during reconnaissance, OSINT investigations, bug bounty hunting, web application testing, and security audits.
In this article, we'll explore how security professionals use Check My Links in real-world environments, why broken links matter from a security perspective, and how this simple extension can accelerate web reconnaissance efforts.
Table of Contents
- What is Check My Links?
- Why Broken Links Matter in Cybersecurity
- Key Features of Check My Links
- Using Check My Links for Reconnaissance
- OSINT Investigation Use Cases
- Bug Bounty Hunting Applications
- Finding Subdomain Takeover Opportunities
- Web Security Audit Benefits
- SEO and Security Connection
- Expert Tips
- FAQ
- Conclusion
What is Check My Links?
Check My Links is a browser extension that automatically scans all links on a webpage and verifies whether they are working correctly.
The extension highlights:
- Valid links
- Broken links (404 errors)
- Redirected URLs (301 and 302)
- Dead resources
- Misconfigured references
Although originally designed to help website owners identify broken links, cybersecurity professionals have adopted it as a fast reconnaissance and asset-discovery tool.
The extension works with:
- Google Chrome
- Microsoft Edge
- Brave Browser
- Opera
- Vivaldi
- Arc Browser
- Most Chromium-based browsers
Why Broken Links Matter in Cybersecurity?
Many organizations view broken links as a user-experience issue. Attackers often see them differently.
A broken link may indicate:
- Retired infrastructure
- Forgotten web applications
- Abandoned cloud resources
- Unmaintained subdomains
- Legacy systems
- Internal development environments accidentally exposed
From a security standpoint, every abandoned resource represents a potential entry point.
Security teams frequently discover attack surfaces by analyzing links that developers and administrators forgot existed.
Key Features of Check My Links
1. Fast Broken Link Detection
The extension automatically checks every hyperlink on a webpage and identifies broken URLs within seconds.
This saves analysts from manually testing dozens or hundreds of links.
2. Redirect Chain Discovery
Many websites contain redirect chains involving:
- 301 Permanent Redirects
- 302 Temporary Redirects
- Multiple hop redirects
Redirect chains can reveal legacy domains, old infrastructure, and migration artifacts.
3. Legacy Asset Identification
Broken references often point toward:
- Deprecated portals
- Old applications
- Retired development systems
- Forgotten cloud deployments
These assets may still be accessible even after being removed from public navigation menus.
4. Automated Link Enumeration
Instead of manually inspecting source code, analysts can quickly map page relationships through automatically detected links.
5. External Link Analysis
External URLs can provide valuable intelligence regarding:
- Third-party vendors
- Cloud providers
- Partners
- Acquired companies
- Historical infrastructure
Using Check My Links for Reconnaissance
Reconnaissance is one of the most important phases of any penetration test or bug bounty engagement.
Before testing vulnerabilities, security researchers attempt to understand the target environment.
Check My Links helps by exposing hidden paths that may not be immediately visible.
For example, while assessing a corporate website, you might discover links pointing to:
- support.company.com
- oldportal.company.com
- archive.company.com
- legacy.company.com
Some of these resources may no longer appear in navigation menus but remain publicly accessible.
This provides additional attack surface for security testing.
Recon Workflow Example
- Open target website.
- Run Check My Links.
- Review broken links.
- Identify unusual URLs.
- Investigate discovered subdomains.
- Perform additional enumeration.
This process often uncovers assets missed during traditional crawling.
OSINT Investigation Use Cases
Open Source Intelligence (OSINT) relies on collecting publicly available information.
Check My Links can significantly improve OSINT investigations by identifying historical and external relationships.
Discovering Historical Infrastructure
Old links often reveal:
- Previous hosting providers
- Legacy domains
- Past acquisitions
- Archived services
Identifying Third-Party Dependencies
External references may indicate partnerships with:
- Cloud vendors
- SaaS providers
- CDN platforms
- Marketing services
This information can help analysts better understand an organization's digital footprint.
Timeline Analysis
Abandoned URLs frequently expose clues about infrastructure evolution over time.
This can be valuable during threat intelligence investigations and attribution efforts.
Bug Bounty Hunting Applications
Experienced bug bounty hunters rarely rely solely on vulnerability scanners.
Instead, they focus on uncovering overlooked assets.
Check My Links supports this methodology by helping identify:
- Hidden endpoints
- Forgotten applications
- Legacy login portals
- Unmaintained web services
- Retired APIs
Many valid bug bounty findings originate from neglected systems rather than actively maintained applications.
Broken links often serve as breadcrumbs leading researchers toward those systems.
Finding Potential Subdomain Takeover Opportunities
One of the most interesting security use cases involves subdomain takeover research.
Organizations frequently retire cloud resources but forget DNS entries that still reference those services.
Broken links may expose subdomains connected to:
- GitHub Pages
- Azure resources
- AWS services
- Heroku applications
- Shopify stores
- Other cloud-hosted platforms
If the underlying service is removed while DNS records remain active, a subdomain takeover risk may exist.
While Check My Links alone cannot confirm takeover vulnerabilities, it can help analysts identify candidate targets for further investigation.
How Security Auditors Use Check My Links?
Security audits often require assessing the overall health of a web environment.
Check My Links helps auditors:
- Identify outdated references
- Locate abandoned resources
- Verify migration completeness
- Find broken security-related pages
- Discover forgotten infrastructure
Large enterprises often operate hundreds of websites and web applications.
Over time, maintaining accurate link structures becomes challenging.
This creates opportunities for attackers and compliance concerns for defenders.
The Connection Between SEO and Security
SEO teams and cybersecurity teams often work independently, but both groups care about broken links.
From an SEO perspective, broken links harm search engine rankings and user experience.
From a security perspective, they may indicate:
- Poor asset management
- Shadow IT
- Untracked infrastructure
- Configuration drift
- Potential attack surfaces
Organizations that regularly audit broken links tend to maintain stronger visibility into their digital assets.
Better visibility often translates into better security.
Expert Tips from Real-World Assessments
Don't Ignore 301 Redirects
Many analysts focus only on 404 errors.
In practice, redirect chains frequently reveal more valuable information than broken links.
Analyze External Domains
Third-party references can expose suppliers, vendors, and cloud providers that help map an organization's ecosystem.
Check Historical URLs
If a link is broken today, investigate whether archived versions exist through publicly available web archives.
Combine with Other Recon Tools
Check My Links works exceptionally well alongside:
- Burp Suite
- OWASP Amass
- Subfinder
- Assetfinder
- Wayback Machine
- Google Dorking
- SecurityTrails
Review Every Abandoned Resource
Many high-impact discoveries originate from assets that organizations believe no longer exist.
Always investigate suspicious URLs further.
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Frequently Asked Questions (FAQ)
Is Check My Links a hacking tool?
No. It is primarily a link-checking extension. However, cybersecurity professionals use it during reconnaissance and security assessments.
Can Check My Links find vulnerabilities?
Not directly. It helps identify potential attack surfaces and forgotten resources that may warrant further investigation.
Is it useful for bug bounty hunting?
Yes. Many bug bounty hunters use it to discover hidden URLs, abandoned assets, and legacy infrastructure.
Does it detect subdomain takeover vulnerabilities?
No. It only helps identify candidate URLs that may require additional takeover verification.
Can SOC analysts benefit from this extension?
Yes. SOC teams performing threat hunting, asset discovery, and exposure assessments can use it to improve visibility.
Which browsers support Check My Links?
It supports Chrome, Edge, Brave, Opera, Vivaldi, Arc, and most Chromium-based browsers.
Does it require advanced cybersecurity knowledge?
No. Beginners can use it effectively, while experienced analysts can incorporate it into larger reconnaissance workflows.
Conclusion
Check My Links may appear to be a simple SEO utility, but in the hands of a cybersecurity professional, it becomes a surprisingly effective reconnaissance tool.
Broken links often reveal far more than missing webpages. They can expose forgotten subdomains, legacy applications, abandoned infrastructure, redirect chains, and hidden resources that attackers and defenders alike are interested in finding.
Whether you're conducting a bug bounty assessment, performing OSINT research, auditing enterprise web assets, or mapping a target's digital footprint, Check My Links can dramatically reduce the time required to uncover valuable intelligence.
In modern cybersecurity, visibility is everything. Sometimes the fastest way to discover hidden attack surfaces is simply to follow the links everyone else ignored.