This article is based on a Q&A originally published by App Developer Magazine, featuring Ravi Balupari, co-founder and VP of Engineering and Threat Research at CloudVector.
The Shift Left Movement and API Security
One of the defining trends in modern DevOps is the “shift left” approach to security—moving security concerns earlier into the development lifecycle rather than bolting them on at the end. This convergence of security and development has given rise to the term DevSecOps, and it has reshaped conference agendas, tooling strategies, and team structures across the industry.
But shifting left requires practical tools, not just philosophy. One of the most effective and frequently overlooked tools for achieving this is the API catalog. Understanding what an API catalog is, how to build one, and how to use it across the CI/CD pipeline can measurably improve both application quality and security posture.
What Is an API Catalog?
An API catalog is a living document—or structured registry—of every API that an enterprise consumes, exposes, or integrates into its application stack. Each entry in the catalog typically includes the API’s specification: data types, endpoint URLs, parameters, transport protocols, authentication and authorization mechanisms, and access control rules.
It also carries metadata about each API, such as:
- Creator and maintainer
- Date last modified
- The application it belongs to
- Environment (dev, test, production)
- Whether parameters are required or optional
- Data type bounds and constraints
- A brief description of the data each parameter carries
Maintaining a complete and current API catalog is considered a DevOps best practice because it provides a shared source of truth that all teams—development, QA, operations, and security—can reference throughout the application lifecycle.
API Catalog vs. API Specification vs. API Blueprint
These terms are often used interchangeably, which causes confusion. Here is a practical breakdown:
- API specification and API blueprint are effectively the same thing: a formal description of how a single API is designed and how it should be used.
- API catalog is the collection—an inventory of all APIs in your ecosystem, each described by its own specification or blueprint, plus the metadata about each one.
Think of individual API specifications as blueprints for individual components, while the catalog is the master index of all those blueprints across a project or organization.
How to Generate and Maintain an API Catalog
At a high level, there are two approaches to creating an API catalog:
1. Manual Documentation
Developers manually capture API blueprints and specifications—including parameters, methods, and endpoint details—and store them in a cataloging system. This could be an internal wiki, a shared spreadsheet, or a dedicated solution such as MuleSoft Anypoint Exchange.
Storing API specifications in plaintext repositories (like an unstructured GitHub folder) or sharing them ad hoc over Slack is not recommended, as it makes discovery, versioning, and auditing unreliable.
A critical discipline with manual cataloging: every time an API changes, its catalog entry must be updated. Stale catalog entries are worse than no entry, because they create a false sense of documentation coverage.
2. Automated Discovery
API gateways can store API specifications and provide some degree of visibility, but they do not automatically generate or continuously maintain a full API catalog. Dedicated API observability tools can enable automatic and continuous API discovery, which helps keep the catalog current without relying entirely on manual updates.
Integrating the API Catalog into Your CI/CD Pipeline
The real power of an API catalog emerges when it is actively used at each stage of the software delivery pipeline. The recommended approach is to verify the API catalog throughout the CI/CD process—trusting but always checking.
Development Environment: The Golden Image
When your API catalog is first established in a development environment, it becomes your baseline or “golden image.” This is the authoritative reference for what APIs your application should expose and consume. It forms the foundation upon which testing and production environments are validated.
Test Environment: Quality Assurance and Gap Detection
When code moves into a test environment, the test-environment API catalog should be maintained and actively compared against the development catalog. This comparison surfaces two critical classes of issues:
- API in dev catalog but not in test catalog: QA missed testing that API. This is a process gap that could allow untested code to reach production.
- API in test catalog but not in dev catalog: The dev catalog is incomplete—it was never the true golden image. This invalidates assumptions made downstream.
Catching these discrepancies in the test phase is far cheaper than discovering them in production.
Production Environment: Real-World Validation and Risk Exposure
In production, the API catalog should reflect real-world application access patterns. Comparing the production catalog against the dev and test catalogs reveals additional issues:
- API in test catalog but not in production: This API is not being used in the real world. QA may have been testing for a use case that does not exist, and those development cycles could be redirected.
- API in production but not in the test catalog: This API has bypassed QA and security testing entirely. It is a Shadow API—a serious security risk. Threat actors actively search for undocumented or unmonitored APIs to exploit.
Using the API Catalog for Security and Risk Assessment
Security teams benefit directly when development teams maintain a rigorous API catalog. Specifically:
- The catalog gives security engineers a complete picture of the attack surface—every API endpoint that exists across environments.
- Cross-environment comparisons help identify Shadow APIs, which are prime targets for exploitation precisely because they have not undergone security review.
- A current, accurate API catalog enables more targeted and effective application security testing (AST), since testers know exactly what they are supposed to be testing.
- It supports risk scoring and prioritization: APIs that handle sensitive data types or use weak authentication can be flagged for deeper review.
For organizations implementing a DevSecOps model, the API catalog is one of the most direct mechanisms for giving security teams actionable, developer-generated intelligence.
Practical Recommendations
- Choose a structured cataloging tool rather than informal storage (wikis, spreadsheets, or Slack). Dedicated API management platforms offer versioning, search, and access controls that informal tools cannot.
- Enforce catalog updates as part of your definition of done. An API change that is not reflected in the catalog breaks the baseline for all downstream environments.
- Automate discovery where possible. Manual-only processes drift over time. Automated API observability tools can continuously surface APIs that are active in an environment but not reflected in the catalog.
- Run catalog diff checks as a CI/CD gate. Treat a significant discrepancy between the dev and test catalogs as a build failure—not a post-deployment finding.
- Involve security teams early. Share the API catalog with security engineers during sprint planning and test design, not just at audit time.
Summary
An API catalog is not documentation for its own sake. Maintained accurately and compared systematically across development, test, and production environments, it becomes a powerful instrument for quality assurance, process validation, and security risk detection. For teams serious about shifting security left, the API catalog deserves a first-class role in the CI/CD pipeline.
This article is based on a Q&A with Ravi Balupari, co-founder and VP of Engineering and Threat Research at CloudVector, where he led the development of their API Threat Protection platform. He previously served as Head of Threat Research at Netskope and spent ten years as a security researcher at McAfee. Original source: App Developer Magazine.