Last updated: May 2026
Azure App ServiceBeginnerAZ-104⏱ 11 min read
Azure App Service Overview
Azure App Service is a fully managed Platform-as-a-Service (PaaS) for hosting web applications, REST APIs, and mobile backends. You bring your code — Azure handles the infrastructure: OS patching, load balancing, auto-scaling, SSL certificates, and high availability. It supports .NET, Node.js, Python, Java, PHP, Ruby, and custom containers — making it the most versatile web hosting service in Azure.
What you'll learn
What App Service is and what it handles for you · Supported runtimes and OS options · App Service components — Web Apps, API Apps, Mobile Apps, WebJobs · The App Service Plan concept · Key features overview · App Service vs alternatives (VMs, AKS, Azure Functions) · When to choose App Service
What is App Service?
App Service is HTTP-based hosting for web applications. When you deploy to App Service, Microsoft manages:
- Physical and virtual servers
- Operating system updates and security patches
- Load balancing across instances
- Network infrastructure
- SSL/TLS certificate management
- Built-in availability (99.95% SLA on Standard and above)
You manage only your application code and configuration.
ℹ️
App Service Plan = The Server Every App Service app runs on an App Service Plan — which defines the underlying compute (VM size and count). Multiple apps can share the same plan. The plan is what you pay for — apps themselves are free.
Supported Runtimes
| Runtime | Windows | Linux | Versions |
|---|
| .NET | ✅ | ✅ | .NET 6, 7, 8, Framework 4.8 |
| Node.js | ✅ | ✅ | 18, 20, 22 |
| Python | ✅ | ✅ | 3.9, 3.10, 3.11, 3.12 |
| Java | ✅ | ✅ | Java 8, 11, 17, 21 |
| PHP | ✅ | ✅ | 8.0, 8.1, 8.2, 8.3 |
| Ruby | ❌ | ✅ | 3.2, 3.3 |
| Custom container | ✅ (Windows containers) | ✅ (Docker) | Any |
App Service App Types
Web Apps
The core offering — host any web application or REST API. The most commonly used App Service type. Supports all runtimes listed above.
API Apps
Specialised for REST APIs — same infrastructure as Web Apps but with built-in Swagger/OpenAPI support and CORS configuration. Most teams just use Web Apps for APIs too.
Mobile Apps
Backend for mobile applications — provides data sync, push notifications, and authentication for iOS/Android apps. Less commonly used today (most use Web Apps with a REST API instead).
WebJobs
Background task runner attached to a Web App. Run scripts or programs (shell scripts, .NET, Node, Python) continuously, on a schedule (cron), or triggered. WebJobs share the same App Service Plan as the parent Web App.
💡
WebJobs vs Azure Functions WebJobs run alongside a Web App and share its compute. Azure Functions are serverless — billed per execution. Use WebJobs for background tasks tightly coupled to your web app. Use Functions for event-driven, independently scalable tasks.
Key Features
| Feature | Description |
|---|
| Deployment slots | Staging environments — deploy to staging, test, then swap to production with zero downtime |
| Auto-scaling | Scale out to more instances based on CPU, memory, or custom metrics |
| Custom domains | Map your own domain (contoso.com) to the app |
| Managed TLS/SSL | Free managed certificates for custom domains |
| Authentication | Built-in auth with Azure AD, Google, Facebook, GitHub — no code changes |
| VNet Integration | Connect app to private VNet for database/service access |
| Deployment Center | CI/CD from GitHub, Azure DevOps, Bitbucket, or local Git |
| Application Insights | Performance monitoring, request tracing, error tracking |
| App Service Environment (ASE) | Fully isolated, private deployment within your VNet |
App Service vs Alternatives
| Service | What You Manage | Best For |
|---|
| App Service | Code + config | Web apps, APIs, standard web workloads |
| Azure Functions | Code only | Event-driven, serverless, short tasks |
| Azure Container Apps | Container + config | Microservices, containerised apps |
| Azure Kubernetes Service | Containers + cluster config | Complex microservices, full control |
| Azure VM | OS + runtime + code | Full control, legacy apps, specific OS |
When to Choose App Service
- Building or migrating a web application or REST API
- Team doesn't want to manage servers or containers
- Need built-in CI/CD, deployment slots, scaling, and SSL
- Running standard runtimes (.NET, Node, Python, Java, PHP)
- Need predictable pricing (always-on vs serverless Functions)
- WordPress or other CMS on PHP
💡
AZ-104 Exam Tip Know that App Service is PaaS — Microsoft manages the OS, patching, and infrastructure. Know that the App Service Plan defines the compute and is what you pay for. Know that multiple apps can share one plan. Know the key features: deployment slots, auto-scaling, VNet integration, custom domains.
Click an option to check your answer.
Q1. In Azure App Service, what resource defines the underlying compute (VM size, instance count) that apps run on?
A — The Web App
B — The App Service Plan
C — The Resource Group
D — The Deployment Slot
Q2. Which App Service feature allows you to deploy to a staging environment and then swap to production with zero downtime?
A — VNet Integration
B — Deployment Slots
C — WebJobs
D — Application Insights
Q3. Does Azure App Service support Linux as an OS for running Python applications?
A — Yes — Python is fully supported on Linux App Service
B — No — Python is only supported on Windows App Service
C — Only via custom container on Linux
D — Only on Premium tier Linux plans
Q4. What is the difference between a WebJob and Azure Functions for background processing?
A — WebJobs support scheduling; Azure Functions do not
B — WebJobs share the App Service Plan compute; Functions are serverless and scale independently
C — WebJobs only support .NET; Functions support all languages
D — WebJobs cannot be triggered by events
Q5. Which service should you choose for a containerised microservices application requiring Kubernetes orchestration?
A — Azure App Service
B — Azure Functions
C — Azure Kubernetes Service (AKS)
D — Azure Virtual Machines
Disclaimer: RedKite Cloud is an independent educational resource and is not affiliated with Microsoft Corporation.