APIs are the essential building blocks that allow different parts of modern systems to communicate and innovate. However, the decentralized nature of modern API development often leads individual teams and developers, working to quickly deliver features, to inadvertently create new APIs that duplicate existing functionality or introduce inconsistencies.
Imagine you're at a company building a microservice-based banking application. In this company, different teams, such as the payments, accounts, and notifications teams, each build their own APIs to support the features they're responsible for. For example, the payments team builds an API to process transactions, and the notifications team builds one to send alerts when a payment is made.
However, because there's no central API documentation or coordination, the accounts team also builds a similar payment alert API without realizing one already exists.
Over time, multiple APIs begin doing nearly the same thing, but in slightly different ways. Some might use different naming conventions, others may lack authentication, and some may just be poorly documented. This lack of control and visibility creates significant challenges not just for developers struggling to find or build the right service, but also leads to inefficiencies and increased costs for the business. This state of affairs is what we call API sprawl.
This article takes a closer look at what API sprawl is, its causes, why it matters (both technically and for the business), and how you can keep it in check We'll also discuss why API governance is crucial and share practical ways to stay on top of your APIs.
What is API sprawl?
API sprawl is the uncontrolled proliferation of APIs, often resulting from decentralized development and a lack of strategic oversight.
It typically happens in microservices architectures where multiple teams work in parallel and unknowingly build redundant or inconsistent APIs. As more APIs get added, keeping track of them—and managing, securing, or reusing them—becomes a real challenge.
Without coordination, teams often end up building overlapping features or using inconsistent designs. This creates a frustrating experience for developers, who might waste time rebuilding something that already exists, have trouble finding the right API, or run into integration issues due to different design choices.
Figure 1: Consequences of API sprawl
Over time, this slows down development, increases maintenance costs, and introduces risks in system reliability and security.
How does API sprawl happen, and why?
There are several factors that contribute to API sprawl. Some of the most common causes include:
- No central API oversight: When there's no clear process for managing APIs across teams, everyone ends up doing things their own way. This leads to mismatched standards, naming conventions, and security practices that pile up over time.
- Teams building the same thing: It's easy to miss that another team has already built an API with similar functionality. So instead, you build your own, adding more clutter and making it unclear which version should be used.
- Missing or outdated documentation: When API docs are hard to find or no longer accurate, teams are less likely to reuse existing services. Instead, they build new ones, even if they do the exact same thing.
- Rapid team growth or scaling: As your company grows and adds more engineering teams, the rate of API creation also increases. Without a structured approach, everyone ends up building APIs without coordination, which quickly leads to sprawl.
- Absence of reusable design standards: When your team doesn't follow shared design guidelines, APIs can vary widely in how they're structured. This makes integration harder and contributes to a disconnected developer experience.
- Lack of an internal API catalog: If you can't easily browse or search for existing APIs, you'll waste time trying to track them down or skip that step and build your own. Over time, this behavior becomes the norm and contributes to duplicate APIs.
- Overuse of microservices without planning: Microservices naturally lead to more APIs, but without a plan, you can lose visibility into what's been built. This makes your architecture harder to manage and increases the risk of inconsistent or unnecessary APIs.
Symptoms and consequences of API sprawl
There are a few key symptoms that indicate your organization is experiencing API sprawl. The following are some of the most common signs:
- Difficulty in discovering existing APIs: When APIs are scattered and undocumented, it's hard to know what already exists. You might end up spending time digging through codebases or Slack threads instead of building on top of what's already there.
- Increased security risks: If one team builds an API without knowing another team has already done something similar, you get duplicates with different behaviors and sometimes weaker security. That confusion makes it harder to know what's safe to use.
- Redundant development effort: Some APIs might use REST while others use GraphQL; some might require tokens, others nothing at all. As a result, you and your team constantly switch mental models, which slows development and increases the chance of errors.
- Inconsistent developer experience: When APIs sprawl without centralized management, it's easy to miss outdated endpoints or insecure implementations. That opens the door to vulnerabilities you may not even know exist.
- Tougher to maintain and grow: The more APIs you have, the more things can break. Integrations get messier, bugs get harder to trace, and making changes without breaking something becomes a real challenge.
Managing API sprawl
To get a handle on API sprawl, it's important to have a clear plan in place, one that covers visibility, governance, ownership, and managing the API lifecycle. Here are some strategies that can help you take control of your APIs:
Establishing visibility: Know what you have
If you can't see all the APIs your teams are building you can't manage or reuse them effectively. Start by cataloging every API in your organization, whether internal, external, experimental, legacy, and make them accessible through a centralized platform or portal. When APIs are visible and searchable, you reduce duplication, encourage reuse, and make onboarding easier for new team members.
You should also consider tagging APIs by team, status (e.g., beta, stable, deprecated), and usage metrics. This helps you and others understand which APIs are in active use, who owns them, and what needs attention.
Implementing governance without friction
Governance doesn't mean blocking teams; it means giving them just enough guidance to stay consistent. Define lightweight API standards around naming, versioning, authentication, and data formats, and bake these into your developer workflows with tools like linters, checklists, or CI/CD policies. When governance is embedded into how your team works, it feels helpful rather than burdensome.
To make this stick, avoid one-size-fits-all rules and instead provide patterns and templates your team can follow. If you're too strict, teams will work around you; if you're too loose, sprawl continues. Strike a balance where your team feels supported, not slowed down, by the governance model you've put in place.
Assigning ownership and defining lifecycle
If nobody owns an API, it becomes technical debt the moment it's released. Every API should have a clear owner, which is usually the team that built it, and that ownership should be visible in your internal API catalog. This makes it easier for others to report issues, request changes, or understand how long an API will be maintained.
You should also define a standard API lifecycle that includes phases like design, implementation, API testing, release, and deprecation. When you communicate where each API is in its lifecycle, you help other teams plan better and reduce the risk of integrating with unstable or soon-to-be-retired endpoints.
Controlling sprawl across environments
It's easy for your development, staging (test environment), and production environments to each become their own mini-ecosystem of APIs, especially if there's no control or synchronization. You might deploy different versions to different environments, forget to clean up old API endpoints, or allow shadow APIs to sneak into staging and never get removed.
To control this, treat API environments as part of your release strategy. Use consistent naming conventions and deployment processes so that every API is traceable from dev to prod. You should also periodically audit these environments to ensure you're not running APIs that no one uses anymore, or worse, APIs that never should've gone live in the first place.
Monitoring, auditing, and deprecating responsibly
You can't manage what you don't measure. Start monitoring API usage to understand which endpoints are active, which are slow, and which are unused. This gives you the data you need to spot potential risks and make informed decisions about what to improve or retire.
Deprecation is just as important as release. Communicate clearly when an API is being phased out, give your users time to migrate, and track who's still calling deprecated endpoints. By making auditing and deprecation part of your API management routine, you avoid carrying unnecessary baggage and keep your ecosystem clean and reliable.
API sprawl is natural — but controllable
API sprawl is a natural consequence of rapid growth and innovation, especially in microservice architectures. However, it doesn't have to be chaotic or unmanageable.
By establishing visibility, governance, ownership, and lifecycle management, you can tame API sprawl and create a more efficient and effective development environment. It's not about restricting growth; rather, it's about giving teams the structure and tools to grow responsibly.
To effectively gain the necessary visibility and automation needed to keep API sprawl in check, consider leveraging a tool like Blackbird. Its features are designed to directly address key challenges in managing a growing API landscape.
For instance, Blackbird's GitHub integration automatically discovers and imports OpenAPI specifications directly from your repositories, which is crucial for ensuring your API catalog remains always up-to-date and accurately aligned with what's in your codebase.
Beyond documented APIs, if you're working with legacy services or undocumented endpoints, Blackbird offers capabilities to help you generate OpenAPI specs directly from their source code, a vital step in turning fragmented APIs into discoverable, manageable assets.
Whether you're working API-first or code-first, Blackbird becomes the connective tissue across your API ecosystem. It gives your team a single source of truth, accelerates onboarding, and reduces the operational burden of manual tracking. If you're serious about scaling your APIs without losing control, it's time to let Blackbird do the heavy lifting.