API discoverability: Why its important + the risk of Shadow and Zombie APIs

APIs are the backbone of modern digital systems, but managing them effectively is a challenge. Here’s the key takeaway: hidden or unmanaged APIs - like shadow and zombie APIs - pose serious security risks and hinder productivity. Without proper discoverability, businesses face vulnerabilities, inefficiency, and compliance issues.

Key Points#

• API discoverability ensures APIs are easy to locate, understand, and use, improving developer efficiency and security.
• Shadow APIs (undocumented, bypassing oversight) and Zombie APIs (deprecated but still active) expand attack surfaces, making businesses vulnerable.
• Stats to know:
  • 62% of companies manage 100+ APIs.
  • 36% experienced API security incidents last year.
  • 31% of attacks targeted shadow APIs.
• High-profile breaches (e.g., Meta fined €251M, Geico fined $9.75M) highlight the risks of unmanaged APIs.

Solutions#

• Maintain an up-to-date API inventory with automated tools.
• Assign clear ownership and implement lifecycle management policies.
• Use platforms like Zuplo for centralized monitoring, documentation, and security enforcement.
• Collaborate across teams and automate processes to reduce risks and streamline API management.

Bottom line: Proper API discoverability is critical for security, compliance, and operational efficiency. Without it, businesses risk costly breaches, inefficiency, and missed opportunities.

Key Benefits of API Discoverability#

API discoverability reshapes how teams work, collaborate, and innovate.

Better Developer Productivity#

When APIs are easy to find, developers can spend less time hunting for existing functionality and more time building meaningful solutions. This streamlining of development workflows prevents unnecessary duplication and allows teams to focus on delivering new features and improvements.

The results speak for themselves. With a forked collection, developers complete API calls up to 56 times faster. Developers also report being 50% more innovative when equipped with user-friendly tools and processes.

Take PayPal, for example. By improving API discoverability, they slashed their time-to-first-call from 60 minutes to just one minute and cut testing time from hours to mere minutes. Accessible APIs also encourage reuse across teams, ensuring consistency and eliminating redundant efforts across departments.

"The best way to help developers achieve more is not by expecting more, but by improving their experience." - Nicole Forsgren, Founder of DORA metrics and Partner Research Manager, Microsoft

Auto-generated API documentation further simplifies workflows by offering clear, accessible details about interfaces. With less mental effort spent deciphering unclear APIs, teams can focus on solving complex problems. These efficiencies also contribute to stronger security practices by clarifying how APIs should be used and accessed.

Stronger Security Posture#

API discoverability doesn’t just boost productivity - it also strengthens security by exposing hidden vulnerabilities. It’s a straightforward concept: you can’t secure what you don’t know exists. By gaining full visibility into their API landscape, organizations can close security gaps and eliminate blind spots.

The stakes are high. A staggering 92% of organizations reported API-related security incidents in the past year, with 58% identifying APIs as a security risk due to their role in expanding the attack surface. Shadow and zombie APIs - those unknown or forgotten by teams - are often the culprits, creating vulnerabilities that evade security measures.

Comprehensive API discovery maps out the entire API ecosystem, helping security teams identify risks, enforce governance policies, and meet compliance requirements. Considering that only 10% of organizations fully document their APIs, maintaining an accurate inventory is crucial for understanding functionality, managing permissions, and meeting regulatory standards.

Better Collaboration and Ecosystem Growth#

Discoverable APIs break down silos and improve collaboration, both internally and with external partners. By making APIs easier to find and understand, teams can reuse central APIs as shared resources, reducing duplication and ensuring consistent practices. This visibility also aids in managing untracked APIs, further reducing security risks.

The benefits extend beyond individual organizations. For instance, Expedia generates over 90% of its revenue from APIs, while Salesforce’s AppExchange creates over $17 billion in revenue opportunities for its partners annually.

The broader market reflects this growth. The global API management market is expected to reach $8.36 billion by 2028, with a compound annual growth rate (CAGR) of 10.9%. As APIs become more discoverable, organizations can better engage with developers, build thriving ecosystems, and drive continuous innovation.

Understanding Shadow and Zombie APIs#

APIs are essential for modern businesses, but not all of them are properly managed or even accounted for. Some remain hidden or forgotten, creating serious blind spots that can compromise security and disrupt operations. Let’s dig into what shadow and zombie APIs are, and why they’re a growing concern.

What Are Shadow APIs?#

Shadow APIs are essentially rogue APIs that operate outside the oversight of IT and security teams. They often emerge during fast-paced development cycles where speed takes precedence over process. These APIs bypass formal practices like authentication, rate limiting, and logging, making them invisible to API gateways and monitoring tools. The lack of documentation and oversight creates vulnerabilities that attackers can exploit. At their core, shadow APIs reflect organizational gaps - especially the absence of a robust documentation culture.

What Are Zombie APIs?#

Zombie APIs, on the other hand, are leftovers from the past. These are APIs that were once active and properly managed but have since been deprecated or abandoned, yet they remain operational. Over time, as systems evolve, these APIs are forgotten, leaving behind outdated functionality that can be exploited. According to the Salt Security State of API Security report, zombie APIs have been the top API security concern for four consecutive surveys. Unlike shadow APIs, zombie APIs were documented at some point but are no longer actively tracked or maintained. This lack of attention results in old vulnerabilities, such as outdated SSL configurations or obsolete authentication methods.

Both shadow and zombie APIs represent more than just technical oversights - they highlight deeper organizational issues, such as poor deprecation standards and incomplete cleanup processes.

Risks of Shadow and Zombie APIs#

The risks posed by these unmanaged APIs are substantial. Shadow APIs often skip essential security measures, such as proper authentication and encryption. Meanwhile, zombie APIs are no longer patched, leaving them riddled with outdated protocols and known vulnerabilities. Both types expand the attack surface, providing attackers with easy entry points.

Recent data underscores the severity of these risks. A staggering 92% of organizations reported API-related security incidents in the past year, with 58% identifying APIs as a key security risk due to their role in expanding the attack surface. Another survey revealed that 37% of respondents experienced an API security incident in the past year, a significant jump from 17% in 2023.

There’s also a compliance angle to consider. Shadow and zombie APIs can lead to violations of strict data protection regulations, particularly in industries like healthcare (HIPAA) and finance (PCI DSS). Shadow APIs, for instance, can expose sensitive information without proper monitoring, creating risks under GDPR and CCPA.

The consequences of these vulnerabilities are costly. Data breaches linked to shadow or zombie APIs can result in millions of dollars in fines under regulations like GDPR. Operationally, zombie APIs add to technical debt and complicate monitoring, while shadow APIs create unreliable functionality outside of expected channels.

The scope of this issue is massive. On average, a single business application relies on 26 to 50 APIs, and enterprises often manage over 1,000 APIs. Alarmingly, only 10% of organizations fully document their APIs, making the spread of unmanaged shadow and zombie APIs a significant threat.

The real challenge lies in addressing these hidden risks. Shadow and zombie APIs aren’t easily spotted by traditional security tools, yet they dramatically increase the attack surface. Without proper oversight, they weaken an organization’s ability to enforce comprehensive API security across its digital landscape.

Over 10,000 developers trust Zuplo to secure, document, and monetize their APIs

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Strategies for Better API Discoverability and Managing Hidden APIs#

Making APIs easier to find and managing hidden ones requires strong governance, supported by the right tools and processes. Here's how organizations can approach this challenge effectively.

Best Practices for API Inventory Management#

Keeping an up-to-date API inventory (ex. Using API definitions like OpenAPI) is the cornerstone of discoverability. But it's not just about having a list - it's about creating a structured system to document, track, and manage APIs throughout their lifecycle.

• Automate the process: Use discovery tools that scan API traffic and crawl systems to detect APIs automatically.
• Assign ownership: Designate clear API owners to ensure documentation stays accurate and security measures evolve as needed.
• Standardize documentation: Use templates to clearly outline an API’s purpose, version, security requirements, dependencies, and lifecycle stage. This applies to APIs built with REST, GraphQL, and anything else you expose externally.
• Integrate with CI/CD pipelines: Automatically log API changes during development and deployment to keep the inventory current.
• Create a searchable catalog: Organize APIs by functionality, technology, or business domain to make them easy to discover and encourage reuse.

These practices help establish centralized platforms that improve API visibility and governance.

How Zuplo Supports API Discoverability#

Zuplo offers tools that align with these best practices, providing a comprehensive approach to API management. Its programmable API gateway acts as a central hub, monitoring all requests and making it harder for shadow APIs to bypass security controls. You can use the built-in analytics to track usage of individual endpoints, so you can deprecate dead ones before they become zombies.

Zuplo is OpenAPI-native which ensures that documentation stays in sync with actual implementations, reducing the risk of shadow and zombie APIs. Developers benefit from a portal that provides detailed documentation, usage examples, and testing tools, which helps eliminate duplicate or undocumented APIs. Zuplo's API portal is great for cataloging all of your APIs, and is open-sourced as Zudoku. Check it out:

Zuplo also integrates with GitOps to enforce version control and review processes for API changes, maintaining a full audit trail and preventing ad-hoc deployments. Features like advanced authentication and rate limiting further enhance security by identifying and controlling unauthorized API usage.

Tools for Monitoring and Governance#

Strong API governance depends on a combination of monitoring tools and well-defined policies to maintain oversight.

• Endpoint detection: Use tools to flag unauthorized activity and enforce lifecycle policies to keep ungoverned APIs in check.
• Sunset policies: Define clear workflows for API deprecation and deletion.
• Attack surface mapping: Regularly assess the API ecosystem to identify endpoints that may have slipped through monitoring processes.
• Service meshes: Gain detailed insights into API communications, especially in distributed systems and microservices architectures where API sprawl can become a problem.
• Infrastructure monitoring: Track historical usage trends and set up automated alerts to catch unusual behavior early.

Best Practices for Maintaining a Healthy API Ecosystem#

Managing APIs effectively requires ongoing effort and strategic planning. With API attacks surging by over 400% and zombie APIs becoming prime targets, it's clear that a well-maintained API ecosystem is more important than ever. Below are actionable strategies to help ensure your APIs remain secure and resilient.

Continuous API Lifecycle Management#

Proper lifecycle management is key to keeping APIs secure and up-to-date. This involves creating formal policies with scheduled reviews and clear deprecation timelines to avoid APIs lingering indefinitely.

One effective approach is introducing a formal sunset policy that includes well-defined deprecation and deletion workflows. Regular audits and compliance checks ensure all active endpoints meet current security and regulatory standards. Publishing quarterly reports on retired APIs can also provide transparency, detailing why specific endpoints were deprecated and confirming their removal.

Consider these real-world examples: St. Luke's Health System suffered a breach exposing 450,000 patient records because an outdated SOAP API remained active. The vulnerability had been patched in newer services, but the deprecated API went unnoticed for six months, leading to regulatory fines and reputational harm. Similarly, a major US retailer experienced a breach affecting 14 million credit card records after an old checkout API was left active post-migration. The four-month delay in detecting the issue resulted in multimillion-dollar losses and a blow to public trust.

Promoting Cross-Team Collaboration#

Breaking down silos between development, security, and operations teams is essential to prevent shadow APIs and reduce the lifespan of zombie APIs. When teams operate in isolation, governance policies are harder to enforce, and oversight weakens.

Cross-functional collaboration ensures that governance practices are aligned with organizational goals and consistently applied. Clear communication protocols and tools that support both real-time and asynchronous communication are crucial.

Regular meetings, workshops, and training sessions can further enhance collaboration, offering opportunities to align on governance standards and address challenges. Providing targeted training on API lifecycle management, security, and compliance ensures everyone understands their role in maintaining API health.

Using Automation for API Maintenance#

While collaboration sets the foundation for API health, automation takes it to the next level. Managing APIs manually becomes impractical at scale, but automation can streamline processes, reduce risks, and free up developers to focus on innovation.

Incorporating API discovery and security scanning into your CI/CD pipeline helps catch issues before they reach production. Automated cataloging can identify active APIs, including undocumented ones, while continuous monitoring with risk scoring detects unusual access patterns or suspicious behavior. A great tool for analyzing API security across your entire API is RateMyOpenAPI which scans your API for security inconsistencies and vulnerabilities, as well as APIs that don't conform to standards.

The speed advantage is undeniable. AI-powered tools allow developers to ship code many times faster, making robust API security solutions a necessity. Proactive API discovery can operationalize systems in as little as 15 minutes.

Automation should cover the entire API lifecycle - from design and deployment to testing, publishing, and consumption. Automated testing ensures APIs meet their specifications by verifying functionality, efficiency, compatibility, and security. Additionally, automated security processes can identify vulnerabilities, classify sensitive data, and establish baselines for normal behavior.

Assigning clear ownership for each API enhances accountability, while automated tools help maintain independent test cases and minimize dependencies. Regular monitoring ensures that automation efforts are effective and highlights areas needing improvement. This is especially critical given that 92% of organizations reported experiencing an API-related security incident in the past year - yet only 10% fully document their APIs. With the average cost of an API-related breach exceeding $4 million, the stakes couldn't be higher.

Conclusion#

API discoverability isn’t just a technical feature - it’s a critical business necessity that directly influences security, efficiency, and overall success. With API-related attacks on the rise and the cost of a single API security breach averaging $6.1 million - projected to nearly double by 2030 - this is a risk no organization can afford to ignore. Currently, these breaches affect 60% of organizations and contribute to annual losses estimated at a staggering $75 billion. The rapid growth of APIs, coupled with insufficient governance, has created a dangerous gap that businesses must urgently address.

When APIs are properly cataloged, documented, and managed, they become a powerful asset rather than a liability. Organizations that prioritize discoverability can boost developer efficiency, strengthen security measures, and foster better collaboration across teams. This is why 93% of organizations acknowledge APIs as essential to their operations. Visibility is the cornerstone of control, enabling organizations to mitigate risks while unlocking opportunities.

Unmanaged APIs, such as shadow and zombie APIs, pose serious threats. Shadow APIs are undocumented and bypass security protocols, while zombie APIs are outdated endpoints that can serve as entry points for attackers. Tackling these vulnerabilities requires a robust strategy that includes comprehensive lifecycle management, teamwork across departments, and scalable automation tailored to evolving API ecosystems.

Modern solutions, like Zuplo, are designed to meet these challenges head-on. These platforms provide centralized management, precise access control, automated versioning, and seamless OpenAPI synchronization. Tom Carden, Head of Engineering at Rewiring America, highlights the benefits:

"Zuplo is the ultimate one-stop shop for all your API needs. With rate limiting, API key management, and documentation hosting, it saved us weeks of engineering time and let us focus on solving problems unique to our mission."

To stay ahead, organizations must adopt proactive governance and continuous monitoring while leveraging the right tools to maintain visibility across their API landscape. This approach not only ensures security but also paves the way for ongoing innovation and sustainable scaling. Businesses that invest in API discoverability today are positioning themselves to thrive in an increasingly API-driven world.

The health of your API ecosystem directly impacts your ability to deliver value securely and efficiently. By prioritizing discoverability, addressing shadow and zombie APIs, and committing to strong governance, you’ll set the stage for secure growth and long-term success.

FAQs#

What’s the difference between shadow APIs and zombie APIs, and why are they a security concern?#

Shadow APIs refer to undocumented APIs that are created without proper approval or oversight. Since they aren't officially tracked, they often lack the necessary security measures, leaving them open to potential exploitation. Meanwhile, zombie APIs are outdated or abandoned APIs that remain accessible but are no longer actively maintained. These neglected APIs can become easy prey for attackers, as they often contain unpatched vulnerabilities.

Both shadow and zombie APIs expand your system's attack surface, exposing sensitive information and introducing compliance risks. Because they're frequently overlooked, they can lead to severe security breaches if not addressed. To counter these risks, it's crucial to prioritize API visibility and conduct regular audits to keep your systems secure.

How can organizations keep their API inventory up-to-date to improve discoverability and reduce risks from unmanaged APIs?#

To keep your API inventory accurate and current, the key lies in automation and consistent updates. Tools like runtime monitoring and OpenAPI specifications can simplify automated API discovery and documentation. Make it a habit to review and organize your APIs regularly, keeping track of dependencies and usage to maintain transparency and relevance.

Steer clear of static tools like spreadsheets - they become outdated too fast. Instead, opt for dynamic API management platforms that offer real-time updates and actionable insights. Taking this proactive approach not only boosts API discoverability and operational efficiency but also reduces risks, such as security vulnerabilities or compliance gaps, tied to unmanaged APIs.

How does API discoverability boost developer productivity and improve team collaboration?#

API discoverability is crucial for helping developers work smarter and faster. When APIs are easy to find and integrate, developers can save time and avoid the headaches of tracking down hidden or poorly documented APIs.

It also encourages smoother teamwork. A well-organized and transparent API ecosystem ensures that everyone on the team has access to the same resources. This not only helps prevent redundant work but also promotes consistency across projects, making collaboration more seamless.