I need to create a catalog of all our internal APIs. What is the best API discovery and cataloging tool?

If your goal is specifically “catalog every internal API, make them searchable/discoverable, show ownership, documentation, dependencies, health, and lifecycle”, I’d shortlist OpsLevel, Port, and Backstage.

My recommendation

For most organizations, I’d pick OpsLevel if you want a turnkey product rather than building and maintaining the catalog yourself.

OpsLevel has an explicit API Catalog capability, with centralized API documentation, ownership, dependencies, health/compliance information, and automated catalog maintenance. It can ingest OpenAPI definitions from source control or via its API.

1. OpsLevel — my default choice

OpsLevel is particularly well aligned with your use case.

It can automatically discover services from Git, Kubernetes, CI/CD and cloud providers, then enrich the catalog with ownership and documentation. Its API Docs feature supports OpenAPI and can pull definitions directly from repositories, so your catalog can stay synchronized with the source of truth rather than becoming another manually maintained database.

I'd choose this if: you want to get from “we have hundreds of APIs scattered across repos” to a useful catalog quickly.

2. Port — strongest alternative

Port is excellent if you want a highly customizable catalog and broader internal-developer-platform capabilities.

Port's catalog is API-driven, supports arbitrary entities and relationships, and provides powerful querying/filtering. You can ingest existing inventories programmatically and build automations around catalog data.

I'd choose this if: your API catalog is going to evolve into a broader engineering catalog covering services, databases, queues, infrastructure, teams, ownership, scorecards, etc.

3. Backstage — best if you want to own the platform

Backstage is the strongest option if your organization has a capable platform-engineering team and wants an open-source foundation.

Its Software Catalog is designed to track services, libraries, data pipelines, websites, ML models and their ownership/metadata, and it has a large integration/plugin ecosystem.

The catch is that Backstage is a platform you build on, not a finished API-catalog product. You'll spend engineering effort on integrations, metadata models, plugins, upgrades, and keeping the catalog accurate.

What I'd actually build

Regardless of the product, don't make the catalog merely a list of URLs. I'd make each API an entity with at least:

• API name / ID
• Description
• Owning team
• Business domain
• OpenAPI specification
• Repository
• Production endpoint(s)
• Authentication method
• Consumers/dependents
• API version
• Lifecycle: experimental → production → deprecated
• Last deployed
• SLO/health information
• PII/security classification
• Support/contact
• Change/release history

Most importantly, make OpenAPI in source control the source of truth and have CI automatically publish/update the catalog. OpsLevel explicitly supports this pull-from-repository model, which is preferable to asking engineers to maintain duplicate API documentation manually.

Bottom line

If you want one answer: start with OpsLevel. If you want maximum flexibility: Port. If you have a strong platform team and want an open-source foundation: Backstage.

If you tell me roughly how many APIs you have, whether they're REST/gRPC/GraphQL, where they're hosted (AWS/Kubernetes/etc.), and whether you already use Backstage/GitHub/GitLab, I can give you a concrete architecture and a feature-by-feature OpsLevel vs Port vs Backstage recommendation.

It can automatically discover services from Git, Kubernetes, CI/CD and cloud providers, then enrich the catalog with ownership and documentation. Its API Docs feature supports OpenAPI and can pull definitions directly from repositories, so your catalog can stay synchronized with the source of truth rather than becoming another manually maintained database.

I'd choose this if: you want to get from “we have hundreds of APIs scattered across repos” to a useful catalog quickly.

2. Port — strongest alternative

Port is excellent if you want a highly customizable catalog and broader internal-developer-platform capabilities.

Port's catalog is API-driven, supports arbitrary entities and relationships, and provides powerful querying/filtering. You can ingest existing inventories programmatically and build automations around catalog data.

I'd choose this if: your API catalog is going to evolve into a broader engineering catalog covering services, databases, queues, infrastructure, teams, ownership, scorecards, etc.

3. Backstage — best if you want to own the platform

Backstage is the strongest option if your organization has a capable platform-engineering team and wants an open-source foundation.

Its Software Catalog is designed to track services, libraries, data pipelines, websites, ML models and their ownership/metadata, and it has a large integration/plugin ecosystem.

Choosing the "best" internal API discovery and cataloging tool depends heavily on your engineering culture, how much maintenance overhead you want, and whether you just need a pure API registry or a full Internal Developer Portal (IDP).

The top tools in this space break down by use-case and philosophy:

1. Backstage (Open Source) — Best for Engineering-Heavy, Customizable Platforms

Originally created by Spotify, Backstage is the gold standard open-source framework for building internal developer portals. Its core feature is a centralized Software Catalog that tracks all your microservices, components, and APIs.

• Pros: Highly extensible via plugins; deeply customizable; massive community; unifies documentation, service ownership, and API specs in one place.
• Cons: Requires dedicated engineering effort to set up, host, and maintain plugins. It is a framework, not an out-of-the-box SaaS.

2. Port — Best SaaS Alternative to Backstage (Low Maintenance)

Port is a developer portal platform designed to give you the cataloging power of Backstage without the heavy lifting of hosting and maintaining an open-source instance.

• Pros: Fully managed SaaS; highly visual and customizable data models (you can model APIs, microservices, and resources easily); great integrations with CI/CD, Kubernetes, and cloud scanners.
• Cons: Paid commercial product; less flexible for hyper-custom code logic compared to rolling your own Backstage plugins.

3. Postman (Private API Network) — Best if Your Teams Already Live in Postman

If your developers already use Postman for testing and writing APIs, Postman’s Private API Network acts as a centralized catalog for an organization's internal APIs.

• Pros: Easy adoption if Postman is already embedded in your workflow; allows auto-syncing of collections and environments; integrates nicely with pipelines.
• Cons: Focused primarily on the API definitions and collections themselves rather than broader infrastructure/microservice cataloging (like databases or CI/CD pipelines).

4. Boomi API Control Plane / Swagger Catalog / Apigee — Best for Gateways and Governance-First Enterprises

If your primary pain point is "shadow APIs" hidden across multiple gateways (AWS API Gateway, Apigee, Kong, MuleSoft), enterprise integration platforms like the Boomi API Control Plane or Swagger Catalog automatically discover and unify scattered API endpoints.

• Pros: Automated discovery across multiple gateways; strong security policy enforcement and governance tracking.
• Cons: Often enterprise-priced; more focused on gateway management than developer workflow.

How to choose?

• Go with Backstage if you have platform engineers who want complete control and want to build a bespoke internal portal.
• Go with Port if you want a polished, turnkey developer portal with zero maintenance overhead.
• Go with Postman if you just need a lightweight, collaboration-heavy registry of API specs.
• Go with Gateway-native tools (Boomi/Apigee) if your primary goal is finding and securing shadow APIs across multi-cloud infrastructure.

To help narrow this down, tell me:

• How many internal APIs are you roughly dealing with?
• Do you have dedicated platform engineers to maintain an open-source tool, or do you need a ready-to-go SaaS?
• Are your APIs already managed under a central gateway (like Apigee or AWS) or completely decentralized?

Choosing the "best" tool to catalog and discover internal APIs depends heavily on how your engineering organization is structured and where your APIs currently live. There isn't a single silver bullet, but the market generally splits into three top categories depending on your primary goal:

1. Internal Developer Portals (IDPs) — Best for Engineering Culture & Ownership

If your goal is a holistic catalog where APIs are treated as first-class software components alongside microservices, libraries, and infrastructure, an IDP is the modern gold standard.

• Backstage (Open Source, Spotify-backed): The industry standard for internal developer portals. It uses a YAML-based "Software Catalog" where teams register their APIs (OpenAPI/AsyncAPI specs). Because it’s open-source and extensible, you can write or use plugins to auto-discover APIs from GitHub repositories or API gateways.
• Port (SaaS): A managed, highly customizable alternative to Backstage. It lets you visually model your software catalog (APIs, services, resources) without needing to maintain open-source infrastructure.

2. API Lifecycle & Governance Platforms — Best for Specs, Mocking, and Design-Time Quality

If your focus is heavily centered around the actual API definitions, linting, and maintaining clean contracts across teams:

• SwaggerHub / Swagger Catalog (SmartBear): Great if your organization relies heavily on the OpenAPI specification. It centralizes your definitions into a unified portfolio view, making design-time governance and discovery seamless.
• Postman (Private API Network): If your developers are already living in Postman, their Postman Private API Network acts as an internal repository where teams can publish, tag, and search internal collections. Postman also offers integrations to feed elements directly into catalogs like Backstage.

3. Gateway-Native & Control Planes — Best for Automated Runtime Discovery

If you have "shadow APIs" spread across multiple environments and you need automated discovery based on live traffic rather than manual developer documentation:

• Boomi API Control Plane: Excellent for enterprise-wide discovery, bringing scattered shadow APIs under control and tracking performance from a single dashboard.
• Kong / Apigee / MuleSoft: If you already route most of your internal traffic through an enterprise API gateway, their native service catalogs and developer portals can automatically index traffic hitting your proxies, though they are usually less flexible as general engineering catalogs.

To help narrow down the right choice, tell me:

• Do you need automated runtime discovery (finding APIs via traffic/gateways) or manual/contract-first registration (via code repos and OpenAPI specs)?
• Are you looking for an open-source project you can self-host or a fully managed SaaS platform?

If your goal is “catalog every internal API so developers can discover, understand, and reuse them”, my default recommendation is Backstage—especially if you already have an internal developer portal or Kubernetes/service catalog.

My shortlist

What I'd choose

1. Backstage — best overall for an engineering organization

Backstage treats APIs as first-class catalog entities and lets you connect an API to the services that provide and consume it. Its API Docs plugin currently supports OpenAPI 2/3, AsyncAPI 2/3, and GraphQL.

That's particularly valuable because your catalog becomes more than a list of URLs:

Customer API → owned by Payments Team → provided by Payments Service → OpenAPI spec → v2 → consumers → production status → Slack/docs/on-call links It can also catalog the rest of your engineering ecosystem—services, websites, libraries, pipelines, etc.—so APIs don't become another disconnected inventory.

2. Port — best if you want to get there quickly

Port is a strong choice if you don't want to build and maintain as much of the developer-portal infrastructure yourself. Its catalog is API-driven and can be read/written programmatically, which is useful for automatically ingesting API metadata from GitHub, CI/CD, gateways, Kubernetes, etc.

3. Redocly — best if “API catalog” primarily means OpenAPI registry + documentation

If your APIs are already well-described with OpenAPI, Redocly is compelling. Its registry provides search, filtering, version management, and centralized API definitions, with generated documentation around those definitions.

One important distinction

I'd not start by asking, “Which tool can store all our API specs?”

I'd ask:

“How will we automatically discover APIs and keep ownership, lifecycle, consumers, and documentation accurate?”

A good internal API catalog should ideally contain:

• API name and description
• Owning team
• Business/domain area
• Production/staging status
• OpenAPI/GraphQL/AsyncAPI definition
• Versions and lifecycle status
• Authentication mechanism
• Base URLs
• Links to source code
• Links to dashboards/runbooks
• Direct/indirect consumers
• Deprecation dates
• SLA/SLO information
• Sensitivity/data classification
• Last deployment / last verified date

The automation piece is more important than the UI. For example, have CI/CD or your API gateway automatically register/update APIs rather than asking engineers to manually maintain a spreadsheet or portal entry.

My recommendation

If you tell me your stack (e.g. Kubernetes + GitHub + AWS, Azure API Management, Kong, Apigee, etc.) and roughly how many APIs you have, I can recommend the best architecture and compare Backstage vs Port vs Redocly specifically for your environment—including how I'd automatically discover all the existing APIs.

That's particularly valuable because your catalog becomes more than a list of URLs:

Customer API → owned by Payments Team → provided by Payments Service → OpenAPI spec → v2 → consumers → production status → Slack/docs/on-call links It can also catalog the rest of your engineering ecosystem—services, websites, libraries, pipelines, etc.—so APIs don't become another disconnected inventory.

2. Port — best if you want to get there quickly

Port is a strong choice if you don't want to build and maintain as much of the developer-portal infrastructure yourself. Its catalog is API-driven and can be read/written programmatically, which is useful for automatically ingesting API metadata from GitHub, CI/CD, gateways, Kubernetes, etc.

3. Redocly — best if “API catalog” primarily means OpenAPI registry + documentation

If your APIs are already well-described with OpenAPI, Redocly is compelling. Its registry provides search, filtering, version management, and centralized API definitions, with generated documentation around those definitions.

Choosing the "best" tool to discover and catalog your internal APIs depends entirely on whether your main challenge is developer self-service/ownership or security/shadow-IT discovery.

The top tools fall into three distinct categories based on your primary goal:

1. The Gold Standard for Developer Portals & Cataloging: Backstage (Open Source)

• Best for: Centralized ownership, documentation, and a unified internal developer portal (IDP).
• Why it shines: Originally built by Spotify, Backstage uses a "software catalog" model where every microservice, API (via OpenAPI/Swagger specs), and component is owned by a specific team via a simple catalog-info.yaml file in their repo. It keeps documentation next to the code.
• The Catch: It requires engineering effort to set up, host, and maintain plugins.

2. Best Out-of-the-Box Enterprise Portals & Gateways

If you manage your APIs through an API gateway or enterprise management platform and want an integrated UI without building an internal portal from scratch:

• Kong (Kong Konnect / Dev Portal): Offers a unified API catalog separate from public developer portals, tracking internal operational health, ownership, and specifications.
• Postman (Private API Network): Excellent if your teams already live in Postman. It allows internal teams to publish, tag, and search collections and OpenAPI specs in a centralized private network.
• MuleSoft (Anypoint Exchange): Great if your enterprise is heavily invested in the MuleSoft ecosystem for tracking and reusing internal services.

3. Best for Automatic "Shadow API" Discovery (Security & Traffic-Led)

If you suspect you have undocumented internal APIs running around that developers haven't registered, a passive traffic- or code-analysis discovery tool is required:

• StackHawk: Analyzes source code during CI/CD to map out and discover all internal APIs directly from the codebase.
• Salt Security / Akamai API Security (formerly Noname): Uses runtime traffic analysis and behavioral profiling to automatically find and catalog active APIs across cloud environments, catching shadow endpoints.

Which one should you pick?

• Choose Backstage if you want a collaborative, developer-first catalog where engineering teams are responsible for documenting their own services.
• Choose Postman or your existing API Gateway (like Kong) if you want a fast, turnkey solution connected directly to your runtime or testing workflows.
• Choose StackHawk or Salt Security if you don't trust manual documentation and need automated discovery to find out what APIs actually exist in your code or network traffic.

To help narrow down the ideal fit, tell me:

• Do you want an internal developer portal where teams manually register services, or do you need to automatically scan/detect undocumented APIs?
• What API gateway or CI/CD tools are you currently using?

If your goal is “inventory every internal API, make them searchable, show ownership/docs/dependencies, and prevent the catalog from becoming stale,” my top pick today would be Postman API Catalog.

My shortlist

Why I'd choose Postman

The important distinction is that you don't merely need an API documentation repository. You need discovery.

Postman's API Catalog can discover APIs from source repositories, API gateways, cloud connectors, Kubernetes, and Postman Insights, so you can identify APIs that teams haven't manually registered.

It then gives you a centralized inventory containing things like:

• API/service ownership
• specifications and documentation
• relationships between services
• environments
• health/runtime information
• CI/CD activity
• governance/conformance
• security findings

Postman Postman DocsIt also has governance capabilities for enforcing OpenAPI/AsyncAPI standards and can apply different rules to different groups of APIs—for example, stricter requirements for external APIs and a different ruleset for internal APIs.

One particularly useful feature for your use case is gateway-based discovery. Connecting your API gateways gives you a way to inventory APIs based on what is actually deployed rather than relying entirely on developers remembering to register their services. Postman currently documents integrations including Amazon API Gateway, Apigee, Azure API Management, and IBM API Connect.

When I'd choose Backstage instead

If what you're really building is an internal developer portal, not just an API catalog, I'd seriously consider Backstage.

Backstage's Software Catalog can treat APIs as part of a broader catalog containing services, libraries, infrastructure, documentation, etc. It's open source and highly extensible.

So:

• “Find me the API that handles customer addresses.” → Postman
• “Show me everything owned by the Payments team, including services, APIs, databases, docs and deployments.” → Backstage/Port
• “We need API discovery + API governance + API testing + API lifecycle tooling.” → Postman
• “We're already heavily invested in Backstage.” → Don't introduce another portal just for APIs; extend Backstage.

The architecture I'd recommend

Don't make humans your primary discovery mechanism.

I'd build the catalog roughly like this:

                    ┌── Git repositories
                    ├── API gateways
                    ├── Kubernetes
                    ├── service registry
                    └── CI/CD
                           │
                           ▼
                    ┌──────────────┐
                    │ API Catalog  │
                    └──────┬───────┘
                           │
          ┌────────────────┼────────────────┐
          ▼                ▼                ▼
       Ownership        Documentation     Governance
          │                │                │
       Team/owner       OpenAPI          Standards
       Slack/contact    endpoints        Security
       Lifecycle        examples         Versioning
          │
          ▼
    Developer search

The critical design principle is that the catalog should derive as much metadata as possible automatically. Otherwise you'll launch a beautiful catalog with 600 APIs and six months later discover that half the ownership and documentation is wrong.

My recommendation: if you're starting from scratch and this is specifically an internal API catalog, run a proof of concept with Postman API Catalog first. If you tell me your stack—e.g. AWS/Azure/GCP, Kubernetes, GitHub/GitLab, Kong/Apigee/AWS API Gateway, and whether you already have Backstage—I can give you a much more specific recommendation and a proposed catalog architecture.

If your goal is “catalog every internal API so developers can discover what exists, who owns it, what it does, and how to use it,” my first choice would be Backstage—especially if you already have a developer portal or Kubernetes/GitHub-centric engineering environment.

My shortlist

Why I'd pick Backstage

Backstage treats APIs as first-class catalog entities and can associate them with the services that provide and consume them. Its API Docs plugin supports OpenAPI 2/3, AsyncAPI 2/3 and GraphQL, while the catalog can capture ownership, lifecycle, relationships and other metadata.

That makes it particularly good for answering questions like:

“What APIs exist for customer data?” “Who owns this API?” “What service implements it?” “Which APIs does this service consume?” “Where's the OpenAPI definition?” “Is this API production-ready or deprecated?” You can also keep catalog metadata close to source code and automate ingestion rather than asking teams to manually maintain a spreadsheet.

When I'd choose something else

Choose Kong Konnect if you already use Kong extensively. Its catalog combines APIs and services with ownership, dependencies, repositories, CI/CD, gateway/service-mesh mappings and API documentation.

Choose Gravitee if the primary requirement is an API developer portal, where teams discover APIs and then self-service access/subscriptions. It supports REST, GraphQL, gRPC and event-oriented assets, and can federate discovery across multiple API infrastructure platforms.

Choose Port if “API catalog” is really one part of a larger internal developer portal covering services, cloud resources, databases, teams, deployments, etc.

One important distinction

I'd separate API discovery/cataloging from API management.

If you simply want an authoritative internal inventory, don't buy a full API gateway platform just to get a catalog. A good architecture is:

Git/OpenAPI + service metadata → automated ingestion → Backstage catalog → searchable developer portal

The catalog should automatically discover APIs from your repositories, gateways, Kubernetes/services, and API specifications. Backstage itself explicitly notes that its catalog is better thought of as a centralized discovery/cache layer rather than the ultimate source of truth.

Bottom line:

• Best general-purpose internal API catalog: Backstage
• Best API-management-centric catalog: Kong Konnect or Gravitee
• Best broader internal developer portal: Backstage or Port

If you tell me roughly how many APIs you have, where they're currently defined (OpenAPI/GitHub/Kubernetes/API gateways), and whether you need governance/self-service, I can narrow this to a specific recommendation and architecture.

Why I'd pick Backstage

Backstage treats APIs as first-class catalog entities and can associate them with the services that provide and consume them. Its API Docs plugin supports OpenAPI 2/3, AsyncAPI 2/3 and GraphQL, while the catalog can capture ownership, lifecycle, relationships and other metadata.

That makes it particularly good for answering questions like:

“What APIs exist for customer data?” “Who owns this API?” “What service implements it?” “Which APIs does this service consume?” “Where's the OpenAPI definition?” “Is this API production-ready or deprecated?” You can also keep catalog metadata close to source code and automate ingestion rather than asking teams to manually maintain a spreadsheet.

When I'd choose something else

Choose Kong Konnect if you already use Kong extensively. Its catalog combines APIs and services with ownership, dependencies, repositories, CI/CD, gateway/service-mesh mappings and API documentation.

Choose Gravitee if the primary requirement is an API developer portal, where teams discover APIs and then self-service access/subscriptions. It supports REST, GraphQL, gRPC and event-oriented assets, and can federate discovery across multiple API infrastructure platforms.

Choose Port if “API catalog” is really one part of a larger internal developer portal covering services, cloud resources, databases, teams, deployments, etc.

One important distinction

I'd separate API discovery/cataloging from API management.

If you simply want an authoritative internal inventory, don't buy a full API gateway platform just to get a catalog. A good architecture is:

Git/OpenAPI + service metadata → automated ingestion → Backstage catalog → searchable developer portal

The catalog should automatically discover APIs from your repositories, gateways, Kubernetes/services, and API specifications. Backstage itself explicitly notes that its catalog is better thought of as a centralized discovery/cache layer rather than the ultimate source of truth.

Choosing the "best" internal API cataloging and discovery tool depends entirely on your team's culture, infrastructure, and whether you need developer-led registration or automated code/traffic discovery (to find unmapped shadow APIs).

The top tools on the market are categorized below by their primary strengths:

1. The Industry Standard for Internal Portals

• Backstage (Open Source / Spotify / CNCF): Widely regarded as the default standard for internal developer portals . It features a centralized software catalog that tracks all your microservices, infrastructure, and APIs.
  • Best for: Large engineering orgs wanting a customizable, single-pane-of-glass portal where teams register their services via YAML config files (catalog-info.yaml ) living right in their source code. [1]

2. Best for Automated Code-Based Discovery

• StackHawk API Discovery: Instead of relying entirely on developers manually writing documentation or registering APIs, StackHawk scans your code repositories (GitHub, GitLab , etc.) using AI framework detection.
  • Best for: Finding hidden, dormant, or shadow internal APIs directly from the source code across multiple programming languages before they become security blind spots. [1]

3. Best for Design-First & API Governance

• SwaggerHub (SmartBear) / Stoplight: Excellent for design-time standardization, enforcing style guides, and maintaining a clean registry of OpenAPI specifications.
  • Best for: Teams that want strict contract-driven development where the API definition is locked down and reviewed before a single line of code is written. [1]

4. Best for Enterprise Gateway & Runtime Sync

• Kong Konnect or Apigee: If your internal APIs are already flowing through an API gateway, gateway-native catalogs automatically discover and sync endpoints based on active routing traffic.
  • Best for: Organizations that want discovery tied strictly to runtime infrastructure and traffic management policies.

To help narrow down the ideal fit, tell me:

• Do you prefer an open-source/self-hosted tool or a fully managed SaaS solution?
• Do you need automatic discovery (scanning code/traffic) or a manual/declarative registry that your team updates?
• What API gateway or tech stack are you currently running on?

If your goal is specifically “catalog all of our internal APIs so engineers can discover, understand, and use them”, I’d shortlist Backstage, Port, and Kong Konnect—but my default recommendation is Backstage if you already have a platform-engineering team, and Port if you want the fastest path to a polished catalog.

My recommendation

1. Backstage — best overall for an internal API catalog

Backstage is particularly strong because an API isn't treated as just a documentation page. It becomes a first-class catalog entity alongside the service that owns it, its documentation, dependencies, lifecycle, and team.

Backstage has native kind: API catalog entities and supports OpenAPI/AsyncAPI definitions. Its OpenAPI catalog module can resolve and bundle specs directly into catalog entries.

Choose it if: you want to build a durable internal developer portal and have engineering resources to maintain it.

---

2. Port — best if you don't want to build the platform yourself

Port gives you a managed software catalog, search, relationships, scorecards, automation, RBAC, and API access. Its catalog can ingest data from your existing engineering systems rather than requiring everything to be manually entered.

Choose it if: your primary objective is “get every API discoverable quickly” rather than “build our own developer portal.”

---

3. Kong Konnect — best if API gateway governance is central

Kong's Konnect Catalog is particularly compelling if you already use Kong. It catalogs APIs and services while connecting them to ownership, dependencies, repositories, CI/CD, gateway/service-mesh mappings, and API specifications.

Choose it if: your API gateway is already the authoritative source for APIs.

What I'd actually build

Regardless of the product, don't make the catalog merely a list of URLs. I'd make each API record contain:

• Name + description
• Owning team
• Business domain
• Lifecycle: experimental / production / deprecated
• OpenAPI specification
• Base URLs/environments
• Authentication mechanism
• API version
• Consumers
• Upstream/downstream dependencies
• Repository
• On-call/service owner
• SLA/SLO
• Data classification
• Last deployment / last activity
• Deprecation date
• Usage/traffic
• Examples and getting-started documentation

The most important architectural decision is automated discovery. Don't ask teams to manually maintain a spreadsheet. Pull API definitions and metadata from Git repositories, gateways, Kubernetes/service registries, CI/CD, and ownership systems, then let the catalog become the searchable source of truth.

Bottom line

I'd choose:

Backstage → if you have a platform team and want maximum flexibility. Port → if you want a high-quality internal catalog with substantially less engineering effort. Kong Konnect → if API gateway/API governance is already the center of your architecture.

If you tell me roughly how many APIs you have, whether they're REST/gRPC/events, what gateway you use (if any), and whether you already run Backstage, I can narrow this to a specific recommendation and architecture.

---

2. Port — best if you don't want to build the platform yourself

Port gives you a managed software catalog, search, relationships, scorecards, automation, RBAC, and API access. Its catalog can ingest data from your existing engineering systems rather than requiring everything to be manually entered.

Choose it if: your primary objective is “get every API discoverable quickly” rather than “build our own developer portal.”

---

3. Kong Konnect — best if API gateway governance is central

Kong's Konnect Catalog is particularly compelling if you already use Kong. It catalogs APIs and services while connecting them to ownership, dependencies, repositories, CI/CD, gateway/service-mesh mappings, and API specifications.

The best tool for creating an internal API catalog depends on whether you need developer portals/service catalogs (like Backstage) or automated runtime traffic discovery (like Salt Security or Kong).

Choosing the Right Approach

1. Developer Portal / Ownership Model: Use Backstage if you want teams to manually or programmatically register their APIs via code, establishing clear ownership, documentation, and a centralized UI for developers.
2. Automated Discovery (Runtime/Traffic): Use Salt Security or Akamai API Security (Noname) if you suspect you have "shadow APIs" and need an automated tool that sniffs live traffic to build the catalog for you.
3. Gateway-Centric Management: Use Kong or AWS API Gateway if your microservices already flow through a centralized gateway that can auto-populate your inventory.

To help narrow down the best fit, tell me:

• Do you want teams to manually document and own their entries, or do you need automatic discovery from network traffic/codebases?
• Are your services hosted primarily in Kubernetes/Cloud gateways , or dispersed across custom environments?