Kong vs Apigee vs Gloo API Gateway Interview Questions and Answers

Compare Kong, Google Cloud Apigee, and Gloo Gateway through 15 interview questions and answers. Learn architecture, deployment models, Kubernetes integration, API management, security, analytics, developer portals, performance, pricing considerations, and enterprise selection criteria.

Introduction

Selecting an API Gateway is an important architectural decision for organizations building microservices, cloud-native applications, partner APIs, mobile backends, and public API platforms.

Three commonly evaluated products are:

Kong Gateway
Google Cloud Apigee
Gloo Gateway

Although all three products can route, secure, monitor, and control API traffic, they are designed with different primary strengths.

Kong Gateway is a flexible API Gateway and API management platform known for its plugin ecosystem and multiple deployment options, including traditional, database-less, hybrid, and managed cloud configurations. Kong hybrid mode separates the Control Plane from Data Plane nodes.

Apigee is Google Cloud's enterprise API management platform. It emphasizes API proxies, traffic-management policies, security, analytics, API products, developer portals, and monetization. Apigee supports Google Cloud-hosted and hybrid deployment models.

Gloo Gateway is an Envoy-powered, Kubernetes-native Layer 7 gateway built around cloud-native and Kubernetes Gateway API concepts. It is especially relevant for organizations using Kubernetes, Envoy, Istio, microservices, and modern platform-engineering practices.

This guide covers the 15 most important Kong vs Apigee vs Gloo interview questions with architecture diagrams, feature comparisons, production examples, selection criteria, common mistakes, and enterprise best practices.

What You'll Learn

After completing this guide, you'll understand:

Kong Gateway architecture
Apigee API management architecture
Gloo Gateway architecture
Control Plane and Data Plane separation
API Gateway versus API management
Kubernetes and Envoy integration
Security and traffic-management capabilities
Analytics and developer portals
Extensibility and customization
Deployment models
Operational complexity
Cost and licensing considerations
Enterprise selection criteria
Migration considerations
Production best practices

High-Level Comparison

                       API Platform Requirements
                                │
          ┌─────────────────────┼─────────────────────┐
          │                     │                     │
          ▼                     ▼                     ▼
     Kong Gateway             Apigee            Gloo Gateway
          │                     │                     │
   Flexible Gateway      Full API Management   Kubernetes-Native
          │                     │                     │
    Plugin Ecosystem      Analytics and API       Envoy-Based
          │                 Product Lifecycle          │
          ▼                     ▼                     ▼
 Hybrid / DB-less /       Google Cloud or       Kubernetes Gateway
 Managed Deployment        Hybrid Runtime          API Resources

Quick Comparison Table

Area	Kong	Apigee	Gloo Gateway
Primary positioning	API Gateway and API management	Enterprise API management	Kubernetes-native API Gateway
Data-plane technology	Kong Gateway proxy runtime	Apigee runtime	Envoy proxy
Kubernetes focus	Strong	Supported through hybrid and integrations	Very strong
Managed option	Konnect	Google Cloud Apigee	Solo-managed offerings may vary
Self-managed option	Yes	Apigee hybrid	Yes
Extensibility	Plugins	Policies and extensions	Envoy filters and Kubernetes resources
Developer portal	Available through platform capabilities	Strong API publishing capabilities	Depends on edition and architecture
Analytics	Available	Major platform strength	Commonly integrated with observability tools
Monetization	Depends on platform and edition	Built-in monetization capabilities	Usually handled through additional systems
Best fit	Flexible multi-environment gateway	Enterprise API product management	Kubernetes and platform engineering

1. What is Kong Gateway?

Answer

Kong Gateway is an API Gateway used to route, secure, control, and observe traffic between API consumers and backend services.

It can be deployed in several configurations, including:

Traditional database-backed mode
Database-less mode
Hybrid mode
Managed deployment through Kong Konnect
Kubernetes-based deployments

Kong's hybrid mode separates configuration management in the Control Plane from request processing in the Data Plane.

Architecture

                    API Consumers
                          │
                          ▼
                  Kong Data Plane
                          │
             ┌────────────┼────────────┐
             ▼            ▼            ▼
         User API      Order API    Payment API
                          │
                          ▼
                  Backend Services

              Kong Control Plane
                          │
               Configuration Updates
                          │
                          ▼
                  Kong Data Plane

Key Capabilities

Request routing
Authentication
Rate limiting
Traffic control
Request and response transformation
Logging
Metrics
Plugin-based extensibility
Control Plane and Data Plane separation

Best Fit

Kong is a strong option when an organization needs a flexible gateway that can operate across cloud, on-premises, Kubernetes, and hybrid environments.

2. What is Google Cloud Apigee?

Answer

Apigee is Google's enterprise API management platform.

It places API proxies in front of backend services and applies policies for:

Security
Traffic management
Quotas
Transformation
Caching
Analytics
API product management
Developer onboarding
Monetization

Apigee proxies isolate API consumers from backend implementations, allowing backend systems to change without forcing the same changes on API clients.

Architecture

                 API Consumers
                       │
                       ▼
               Apigee API Proxy
                       │
         ┌─────────────┼─────────────┐
         ▼             ▼             ▼
     Security       Traffic       Transformation
     Policies       Policies         Policies
                       │
                       ▼
               Backend Services
                       │
                       ▼
              Analytics Platform

Key Capabilities

API proxy development
Policy-based security
Traffic management
API products
Developer application registration
Analytics
Developer portals
Monetization
API governance

Best Fit

Apigee is often selected when an enterprise treats APIs as managed business products and requires governance, analytics, developer onboarding, and monetization.

3. What is Gloo Gateway?

Answer

Gloo Gateway is an Envoy-powered, Kubernetes-native API Gateway and ingress solution.

It translates Kubernetes Gateway API and Gloo configuration resources into Envoy configuration distributed through the xDS APIs.

Architecture

             Kubernetes Resources
       HTTPRoute | Gateway | Services
                       │
                       ▼
             Gloo Control Plane
                       │
            Translate Configuration
                       │
                       ▼
                 xDS Snapshot
                       │
                       ▼
                Envoy Gateway
                       │
             ┌─────────┼─────────┐
             ▼         ▼         ▼
         User Pod   Order Pod  Payment Pod

Key Capabilities

Kubernetes Gateway API support
Envoy-based traffic processing
Advanced routing
Kubernetes service discovery
Traffic policies
Security integration
Service-mesh integration
Cloud-native configuration
Multi-gateway deployment

Best Fit

Gloo Gateway is well suited for Kubernetes-first organizations that use Envoy, Istio, GitOps, Gateway API resources, and platform-engineering practices.

4. What is the Main Difference Between Kong, Apigee, and Gloo?

Answer

The primary difference is their platform emphasis.

Kong

↓

Flexible API Gateway
and Plugin Platform

Apigee

↓

Enterprise API Management
and API Product Lifecycle

Gloo Gateway

↓

Kubernetes-Native,
Envoy-Based Traffic Platform

Comparison

Product	Primary Strength
Kong	Flexible gateway deployment and plugin extensibility
Apigee	Enterprise API lifecycle, governance, analytics, and monetization
Gloo Gateway	Kubernetes-native and Envoy-based traffic management

Interview Answer

Kong is commonly chosen for flexible gateway deployments, Apigee for comprehensive enterprise API management, and Gloo Gateway for Kubernetes-native traffic management.

The final selection should depend on organizational requirements rather than a generic product ranking.

5. How Do Their Architectures Differ?

Answer

All three products separate management concerns from runtime traffic processing, but they use different architectural models.

Kong Architecture

Kong Control Plane

↓

Configuration Distribution

↓

Kong Data Plane

↓

Backend APIs

Kong hybrid mode separates Control Plane and Data Plane nodes. Data Plane nodes process API traffic, while the Control Plane manages configuration.

Apigee Architecture

Apigee Management Plane

↓

API Proxy and Policy Configuration

↓

Apigee Runtime

↓

Backend APIs

Apigee uses API proxies and policies to create a managed abstraction layer in front of backend services.

Gloo Architecture

Kubernetes Gateway Resources

↓

Gloo Translation Engine

↓

xDS Configuration

↓

Envoy Proxy

↓

Kubernetes Services

Gloo translates Kubernetes and Gloo resources into Envoy configuration distributed through an xDS server.

6. Which Product is Best for Kubernetes?

Answer

Gloo Gateway has the strongest Kubernetes-native positioning because it is designed around Kubernetes resources, Kubernetes Gateway API, Envoy, and cloud-native traffic management.

Kong also offers strong Kubernetes support and is widely used as an ingress and API Gateway in containerized environments.

Apigee can support Kubernetes and hybrid environments, but its main value extends beyond Kubernetes into enterprise API management, API products, developer programs, analytics, and governance.

Comparison

Requirement	Recommended Consideration
Kubernetes Gateway API	Gloo Gateway
Envoy-based gateway	Gloo Gateway
Kubernetes plus broad plugin ecosystem	Kong
Enterprise API program spanning many platforms	Apigee
On-premises plus cloud gateway flexibility	Kong or Apigee hybrid
Istio-aligned platform	Gloo Gateway

Interview Tip

Do not simply say that Gloo is always better for Kubernetes.

Explain that the decision also depends on:

Existing skills
Security requirements
API management needs
Support model
Operational maturity
Developer portal requirements
Total cost

7. How Do Kong, Apigee, and Gloo Handle Routing?

Answer

All three products support Layer 7 routing, but configuration models differ.

Kong

Kong routes requests through entities such as:

Services
Routes
Consumers
Plugins

Request

↓

Kong Route Match

↓

Kong Service

↓

Backend

Apigee

Apigee uses API proxies and conditional flows.

Request

↓

Proxy Endpoint

↓

Conditional Flow

↓

Target Endpoint

↓

Backend

Gloo Gateway

Gloo commonly uses Kubernetes Gateway API resources.

Gateway

↓

HTTPRoute

↓

Route Match

↓

Kubernetes Service

Routing Capabilities

Path-based routing
Host-based routing
Header-based routing
Method-based routing
Weighted routing
Traffic splitting
Request transformation
Version routing
Canary deployment routing

8. How Do Their Security Capabilities Compare?

Answer

All three products can secure APIs, but their security models differ.

Kong Security

Kong commonly applies security through plugins.

Examples include:

API-key authentication
JWT validation
OAuth2-related integrations
OpenID Connect capabilities
mTLS
IP restrictions
Access-control policies
Rate limiting

Apigee Security

Apigee provides policy-based security controls.

Examples include:

OAuth
JWT validation
API-key verification
Quota policies
Spike arrest
Threat protection
Access-control policies
Certificate-based security

Apigee policies can add security and traffic controls without requiring changes to backend application code.

Gloo Gateway Security

Gloo security commonly integrates with:

Kubernetes secrets
JWT authentication
External authorization
OAuth and OIDC providers
mTLS
Web Application Firewalls
Envoy security filters
Istio service-mesh policies

Enterprise Recommendation

Security selection should consider:

Identity provider integration
Zero Trust requirements
Certificate management
External authorization
Data residency
Audit logging
Compliance
Security-team operating model

9. How Do They Handle Rate Limiting and Traffic Management?

Answer

All three gateways provide traffic-management capabilities.

Kong

Kong commonly uses plugins for:

Rate limiting
Request termination
Traffic control
Caching
Request transformation
Circuit-breaking integrations

Apigee

Apigee provides policies such as:

Quota
Spike Arrest
Caching
Concurrent rate limits
Request validation
Traffic distribution

Apigee policies are attached to API proxy flows and can enforce traffic controls without changing backend services.

Gloo Gateway

Gloo commonly applies:

Local rate limiting
Global rate limiting
Retry policies
Timeouts
Traffic splitting
Fault injection
Header manipulation
Envoy traffic filters

Important Difference

Kong

Plugin-Oriented Configuration

Apigee

API Proxy Policy-Oriented Configuration

Gloo

Kubernetes and Envoy Policy-Oriented Configuration

10. Which Platform Provides Better Analytics?

Answer

Apigee has a strong enterprise analytics focus.

Apigee API Analytics collects information from API proxy traffic and allows teams to visualize or retrieve the data for further analysis. Its availability and packaging can depend on the selected environment and commercial offering.

Apigee Analytics Use Cases

API traffic analysis
Error analysis
Developer usage
Application usage
Proxy performance
Backend latency
API product adoption
Business reporting

Kong Analytics

Kong can provide analytics through its platform offerings and integrations with observability systems such as:

Prometheus
Grafana
OpenTelemetry
Datadog
Splunk
Elastic Stack

Gloo Analytics

Gloo commonly integrates with cloud-native observability tools:

Prometheus
Grafana
OpenTelemetry
Envoy metrics
Distributed tracing platforms

Interview Answer

Apigee is often preferred when built-in enterprise API analytics and business-level API reporting are major requirements.

Kong and Gloo are strong when organizations prefer integrating gateway telemetry with their existing observability platform.

11. Which Platform is Better for Developer Portals and API Monetization?

Answer

Apigee is usually the strongest choice when developer portals, API products, developer application registration, subscriptions, and monetization are major business requirements.

Apigee supports developer portal solutions for publishing API products, managing developer applications, issuing keys, and exposing analytics. It also supports monetization through API-product rate plans.

API Product Lifecycle

Create API Proxy

↓

Create API Product

↓

Publish to Developer Portal

↓

Developer Registers Application

↓

Issue API Credentials

↓

Track API Usage

↓

Apply Subscription or Rate Plan

Comparison

Capability	Kong	Apigee	Gloo Gateway
API gateway	Strong	Strong	Strong
Developer onboarding	Available by platform and edition	Core strength	Usually requires supporting platform capabilities
API products	Supported through platform capabilities	Core strength	Not the primary focus
Monetization	Offering-dependent	Strong built-in capability	Usually external
Business analytics	Available	Strong	Commonly external integrations

12. How Do Their Extensibility Models Differ?

Answer

Each product uses a different extensibility model.

Kong Plugins

Kong uses plugins to add functionality to requests and responses.

Request

↓

Authentication Plugin

↓

Rate-Limiting Plugin

↓

Logging Plugin

↓

Backend Service

Plugins can implement:

Authentication
Rate limiting
Transformations
Logging
Monitoring
Security controls

Apigee Policies

Apigee uses configurable policies attached to API proxy flows.

PreFlow

↓

Authentication Policy

↓

Quota Policy

↓

Transformation Policy

↓

Target Backend

↓

PostFlow

Apigee policies provide reusable traffic, security, and transformation behavior without requiring changes to backend services.

Gloo and Envoy Filters

Gloo uses:

Kubernetes resources
Gateway API policies
Envoy filters
WebAssembly extensions
External authorization services
Custom control-plane integrations

Comparison

Platform	Main Extension Mechanism
Kong	Plugins
Apigee	Policies and proxy flows
Gloo Gateway	Kubernetes policies and Envoy extensions

13. How Do Deployment Models Compare?

Answer

Deployment flexibility is an important selection criterion.

Kong Deployment Models

Kong supports several production deployment models:

Traditional database-backed mode
Database-less mode
Hybrid Control Plane/Data Plane mode
Managed Konnect deployments

Kong documents traditional, hybrid, and DB-less deployment options.

Apigee Deployment Models

Apigee supports:

Google Cloud-managed Apigee
Apigee hybrid
Multiple pricing and consumption approaches

Apigee currently offers evaluation, pay-as-you-go, and subscription pricing approaches, although actual costs depend on environment, usage, and selected features.

Gloo Deployment Models

Gloo Gateway is primarily designed for Kubernetes environments and can support multiple Envoy gateway proxies for different traffic types.

Deployment Comparison

Kong

Cloud | On-Premises | Kubernetes | Hybrid

Apigee

Google Cloud Managed | Hybrid Runtime

Gloo Gateway

Kubernetes | Multi-Cluster | Envoy-Based

14. What are Common Mistakes When Choosing Between Kong, Apigee, and Gloo?

Answer

Organizations often select gateways based on feature lists without considering operating models, team skills, governance requirements, and long-term costs.

Mistake 1: Selecting Only by Performance Benchmarks

Gateway performance depends on:

Policies
Plugins
Payload sizes
TLS
Logging
Network topology
Authentication
Infrastructure sizing

A generic benchmark may not represent the organization's workload.

Mistake 2: Confusing an API Gateway with Complete API Management

An API Gateway mainly processes runtime traffic.

Complete API management may also include:

API design
Developer portals
API products
Analytics
Governance
Monetization
Lifecycle management

Mistake 3: Ignoring Team Skills

A Kubernetes platform team may operate Gloo effectively, while a centralized enterprise API team may prefer Apigee.

Mistake 4: Ignoring Operational Complexity

A self-managed gateway requires:

Upgrades
Scaling
Backup
Monitoring
Certificate rotation
Disaster recovery
Security patching

Mistake 5: Comparing Only License Price

The true cost includes:

Infrastructure
Support
Engineering effort
Operations
Training
Migration
Downtime risk
Observability systems

Mistake 6: Assuming Every Feature Exists in Every Edition

Capabilities can differ between:

Open-source editions
Enterprise editions
Managed services
Add-ons
Subscription tiers

Mistake 7: Ignoring Multi-Region Requirements

The architecture must consider:

Regional availability
Configuration distribution
Data residency
Disaster recovery
Global routing
Control-plane availability

Mistake 8: Putting Business Logic in the Gateway

Gateway policies should focus on cross-cutting concerns rather than core domain logic.

15. How Do You Choose Between Kong, Apigee, and Gloo?

Answer

The correct product depends on business goals, architecture, operating model, and organizational maturity.

Choose Kong When

You need flexible deployment options.
You want a large plugin-based gateway ecosystem.
You operate across cloud, Kubernetes, and on-premises systems.
You need Control Plane and Data Plane separation.
You want both self-managed and managed options.
Your main focus is gateway traffic management with extensibility.

Choose Apigee When

You need comprehensive enterprise API management.
APIs are managed as products.
You need developer portals.
You need built-in analytics.
You require API monetization.
You have strong governance requirements.
You use Google Cloud or need Apigee hybrid.
Business teams need API-usage reporting.

Choose Gloo Gateway When

Kubernetes is the primary application platform.
You use Envoy or Istio.
You want Kubernetes Gateway API resources.
Platform teams manage infrastructure through GitOps.
You need advanced cloud-native routing.
You want strong service-mesh integration.
You operate modern microservices and AI-related traffic patterns.

Decision Flow

Do You Need Full API Product Management,
Developer Portals, and Monetization?
                  │
          ┌───────┴───────┐
          │               │
         Yes              No
          │               │
          ▼               ▼
       Apigee      Is Kubernetes and Envoy
                   the Primary Platform?
                          │
                  ┌───────┴───────┐
                  │               │
                 Yes              No
                  │               │
                  ▼               ▼
          Gloo Gateway          Kong

Enterprise Evaluation Matrix

Score each requirement from 1 to 5.

Requirement	Weight	Kong	Apigee	Gloo
Kubernetes integration	5	4	3	5
Developer portal	4	4	5	2
API analytics	5	4	5	3
Monetization	3	3	5	1
Plugin extensibility	4	5	4	4
Envoy integration	4	2	2	5
Hybrid deployment	5	5	5	4
API governance	5	4	5	3
Cloud portability	4	5	3	5
Managed service	3	5	5	3

These scores are illustrative. Every organization should create its own weighted evaluation based on technical, operational, security, and business requirements.

Production Use Case 1: Public Banking APIs

Requirements

Strong API governance
OAuth2
Partner onboarding
Usage analytics
Developer portal
API products
Monetization or chargeback
Regulatory reporting

Recommended Evaluation

Primary Candidate

↓

Apigee

Apigee may be preferred because the requirements extend beyond request routing into complete API-product management.

Production Use Case 2: Multi-Cloud Microservices Platform

Requirements

Cloud portability
On-premises support
Kubernetes integration
Plugin extensibility
Hybrid Control Plane and Data Plane
Central configuration

Recommended Evaluation

Primary Candidate

↓

Kong

Kong may be preferred because of its deployment flexibility and plugin-oriented platform.

Production Use Case 3: Kubernetes Platform Engineering

Requirements

Kubernetes Gateway API
Envoy
GitOps
Istio integration
Advanced traffic splitting
Multi-cluster routing
Platform-owned policies

Recommended Evaluation

Primary Candidate

↓

Gloo Gateway

Gloo may be preferred because of its Kubernetes-native and Envoy-based architecture.

Proof-of-Concept Evaluation Checklist

Before selecting a gateway, run a proof of concept using realistic traffic and policies.

Functional Tests

Path-based routing
Header-based routing
JWT validation
OAuth2 integration
Rate limiting
Request transformation
Response transformation
Circuit breaking
Retry behavior
API versioning

Performance Tests

Requests per second
P50 latency
P95 latency
P99 latency
TLS overhead
Large payload performance
Authentication overhead
Policy-chain overhead
Scaling behavior

Reliability Tests

Data Plane failure
Control Plane failure
Backend outage
Network partition
Certificate expiration
Configuration rollback
Redis or datastore failure
Multi-region failover

Operational Tests

Installation
Upgrade
Rollback
Backup
Logging
Metrics
Tracing
Alerting
Secret rotation
Disaster recovery

Migration Considerations

Migrating between API Gateway products requires more than converting route definitions.

Migration Areas

Area	Migration Concern
Routes	Product-specific route syntax
Authentication	Different plugins and policies
Rate limits	Different algorithms and storage models
Transformations	Different scripting or policy formats
Certificates	New trust-store and key-store configuration
Analytics	Historical data migration
Developer applications	API-key and consumer migration
Portals	Content and developer-account migration
CI/CD	New deployment automation
Monitoring	New metrics and dashboards

Observability Requirements

Regardless of the selected product, monitor:

Request volume
Error rate
Gateway latency
Backend latency
Authentication failures
Rate-limit rejections
Circuit Breaker state
TLS failures
Route failures
Policy-processing latency
Data Plane health
Control Plane health

Observability Architecture

API Gateway

↓

Metrics | Logs | Traces

↓

OpenTelemetry Collector

↓

Prometheus | Grafana

↓

Splunk | Elastic | Datadog

↓

Alerts and Dashboards

Kong vs Apigee vs Gloo Summary

Concept	Kong	Apigee	Gloo Gateway
Primary focus	Flexible API Gateway	Enterprise API management	Kubernetes-native gateway
Architecture	Gateway runtime with plugins	API proxies and policies	Envoy with Kubernetes control plane
Extensibility	Plugins	Policies	Envoy and Kubernetes extensions
Kubernetes	Strong	Supported	Core strength
Analytics	Platform and integrations	Core strength	External integrations
Developer portal	Available	Core strength	Not the primary focus
Monetization	Offering-dependent	Core strength	Usually external
Deployment	Flexible and hybrid	Managed and hybrid	Kubernetes-first
Service mesh	Integrations available	Integration-dependent	Strong Envoy/Istio alignment
Best use case	Multi-environment gateway	Enterprise API program	Cloud-native platform engineering

Interview Tips

Do not describe Kong, Apigee, and Gloo as identical products.
Explain the difference between an API Gateway and complete API management.
Position Kong around flexibility and plugins.
Position Apigee around API lifecycle, analytics, portals, and monetization.
Position Gloo around Kubernetes, Envoy, and Gateway API.
Explain Control Plane and Data Plane separation.
Discuss managed versus self-managed deployments.
Compare plugins, policies, and Envoy filters.
Explain the importance of operational skills.
Include security, governance, and compliance requirements.
Avoid claiming one platform is universally best.
Discuss total cost of ownership rather than license price alone.
Recommend a production proof of concept.
Include failure, upgrade, and rollback testing.
Use weighted decision criteria to select the platform.

Key Takeaways

Kong, Apigee, and Gloo Gateway can all route and secure API traffic, but their primary strengths differ.
Kong emphasizes flexible deployments, gateway capabilities, and plugin extensibility.
Apigee emphasizes enterprise API management, API proxies, governance, analytics, developer portals, API products, and monetization.
Gloo Gateway emphasizes Kubernetes-native, Envoy-based, and platform-engineering use cases.
Kong hybrid mode separates Control Plane and Data Plane responsibilities.
Apigee uses API proxies and reusable policies to isolate API consumers from backend systems.
Gloo translates Kubernetes resources into Envoy configuration through its control plane.
Apigee is often preferred when APIs are treated as externally published or monetized business products.
Kong is often preferred for flexible multi-cloud, hybrid, and plugin-oriented gateway deployments.
Gloo Gateway is often preferred for Kubernetes Gateway API, Envoy, Istio, and GitOps environments.
Product features may differ across open-source, enterprise, managed, and add-on editions.
Teams should compare total cost of ownership rather than subscription cost alone.
Performance testing must use realistic policies, authentication, TLS, logging, and payloads.
A proof of concept should test functionality, performance, security, failure recovery, upgrades, and operations.
The best gateway is the one that matches the organization's technical architecture, API strategy, operating model, skills, compliance requirements, and budget.