Backend
The server-side part of an application: business logic, data processing, API provision and database access – the invisible foundation of every piece of software.
While the frontend is the visible face of an application, the backend is the engine behind it. Data is processed, business rules enforced, APIs provided and databases managed here. A solid backend is a prerequisite for performance, security and scalability – from a small blog to an enterprise platform.
What is Backend?
The backend (server-side) includes all parts of an application that run on the server and are invisible to the user. It receives requests from the frontend or APIs, runs business logic (e.g. pricing, stock checks, access control), talks to databases and external services and returns results. The backend exposes APIs (REST, GraphQL) used by frontends, mobile apps and third parties. Common backend technologies are Node.js (JavaScript/TypeScript), Python (Django, FastAPI), Java (Spring Boot), .NET (C#) and PHP (Laravel, Symfony).
How does Backend work?
A typical request: 1) Frontend sends an HTTP request (e.g. POST /api/orders). 2) The router forwards to the right controller. 3) Middleware checks authentication (JWT) and authorization (role). 4) Controller runs business logic: validation, stock check, pricing. 5) An ORM (e.g. Prisma, TypeORM) runs database operations. 6) Controller returns JSON. Background jobs (cron, queues) handle async work like email or reports.
Practical Examples
E-commerce backend: Manages catalogue, cart, checkout, payments (Stripe/PayPal) and stock via REST APIs.
CRM backend: Stores contacts, logs interactions, computes lead scores and syncs with marketing tools.
SaaS multi-tenant backend: One codebase serves multiple tenants with isolated data and config.
Real-time backend: WebSocket backend for chat, live dashboards or collaboration.
API gateway: Single entry point that routes to microservices, applies rate limiting and handles auth.
Typical Use Cases
Web apps: API for React/Angular/Vue frontends with auth and data management
Mobile backends: Central logic and data for iOS and Android apps
Microservices: Multiple backend services communicating via APIs and message queues
Data processing: ETL, report generation and analytics in the background
Integration: Connecting ERP, CRM and accounting via backend services
Advantages and Disadvantages
Advantages
- Centralised logic: One codebase for web, mobile and API
- Security: Sensitive operations (auth, payments) run on the server
- Scalability: Horizontal scaling with load balancing and containers
- Technology freedom: Backend can be chosen independently of frontend
- Automation: Background jobs and cron for scheduled tasks
Disadvantages
- Latency: Every API call is a network round-trip – critical when there are many dependent calls
- Complexity: Microservices need service discovery, monitoring and distributed debugging
- Server cost: Backend infrastructure has ongoing cost
- Security responsibility: Backend bugs (e.g. SQL injection, open APIs) have direct impact
Frequently Asked Questions about Backend
Which backend language is best?
What is the difference between backend and frontend?
Do I need my own backend for a small app?
Related Terms
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