Application Load Balancer
An Application Load Balancer (ALB) is a type of load balancer that operates at the application layer (Layer 7) of the OSI model. It intelligently distributes incoming application traffic across multiple backend targets, such as servers, containers, or microservices, based on content of the…
Key facts
- First appeared
- 2000
- Category
- technology
- Problem solved
- Application Load Balancers address the limitations of traditional Layer 4 load balancers by understanding application-level protocols like HTTP/HTTPS. This enables complex routing decisions (e.g., sending /api requests to one service and /web to another), SSL/TLS offloading, content-based routing, host-based routing, and sophisticated health checks that verify application responsiveness rather than just network reachability, significantly improving application resilience, scalability, and security.
- Platforms
- Virtual Machines (software-defined), Hardware Appliances, Cloud Computing Platforms (e.g., AWS, Azure, GCP), Containerized Environments
Related technologies
- Microservices Architectures
- Web Servers (e.g., Nginx, Apache HTTP Server)
- Databases (indirectly, for application connectivity)
- Web Application Firewalls (WAFs)
- API Gateways
- Content Delivery Networks (CDNs)
- Application Servers (e.g., Tomcat, Node.js)
- Container Orchestration Platforms (e.g., Kubernetes, Docker Swarm)
Notable users
- Microsoft Azure (as a core service)
- Uber
- Any enterprise running complex web applications or microservices
- Netflix
- Google Cloud Platform (as a core service)
- Amazon Web Services (as a core service)