Server Load Balancer  Play Video

Server Load Balancer (SLB) distributes network traffic across groups of backend servers to improve the service capability and application availability. It Includes Layer 4 Network Load Balancer (NLB), Layer 7 Application Load Balancer (ALB), and Classic Load Balancer (CLB). It Is the Official Cloud-Native Gateway of Alibaba Cloud.

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Release Notes

Application Load Balancer (ALB) Supports Web Application Firewall (WAF) 3.0 Service Access

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Free Trial for Individuals

Individuals receive a USD $15 and Enterprise receive a USD $55 Classic Load Balancer (CLB) credit

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Latest News

Network Load Balancer (NLB) Has Been Officially Commercially Available, Free of Instance Fees for Limited Time, Welcome to Experience

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High Performance and Elasticity
Stable, Reliable, and Cloud-Native

Server Load Balancer (SLB) provides high-performance load balancing services. with super four-seven processing capabilities.Network Load Balancer (NLB) Provides powerful processing capabilities at Layer 7,A single NLB instance supports 100 million concurrent connections. The newly released Application Load Balancer (ALB) service is based on Alibaba Cloud Apsara Network 2.0 and supports up to 1,000,000 QPS.

The Server Load Balancer (SLB) instances feature high performance and support auto scaling. They can automatically adjust resources based on your business requirements to simplify O&M.

High Security and Reliability

Server Load Balancer (SLB) provides disaster recovery at four levels for high availability. CLB and ALB support built-in Anti-DDoS services to ensure business security. In addition, you can integrate ALB with WAF in the console to ensure security at the application layer.

Multiple Protocols

Server Load Balancer (SLB) supports multiple protocols, such as TCP, UDP and TCPSSL at the network layer, and HTTP, HTTPS, QUIC, and gRPC at the application layer. NLB provides large-scale SSL offloading capabilities,ALB provides multiple advanced routing features at Layer 7.


ALB and CLB support cloud-native networks. ALB is integrated with other cloud-native services, such as Container Service for Kubernetes (ACK), Serverless App Engine (SAE), and Kubernetes, and functions as a cloud-native gateway to distribute inbound network traffic.

SLB Types

Type Network Load Balancer (NLB) Application Load Balancer (ALB) Classic Load Balancer (CLB)
Service Scope Provides powerful processing capabilities at Layer 4 and large-scale SSL offloading capabilities
Intended for TCP, UDP and SSL over TCP
Focuses on network delivery
Provides powerful processing capabilities at Layer 7 and multiple advanced routing features
Supports HTTP, HTTPS, and QUIC at Layer 7
Focuses on application delivery
Provides powerful processing capabilities for Layer 4 load balancing
Supports protocols such as TCP, UDP, HTTP, and HTTPS
Focuses on network delivery
Performance Based on the NFV platform and auto scaling
A single NLB instance supports 100 million concurrent connections
Based on the NFV platform and auto scaling
A single ALB instance supports 1,000,000 QPS
Developed on top of a physical machine architecture
Supports up to 5,000,000 connections
O&M Supports auto scaling to adjust processing capabilities based on inbound traffic Supports auto scaling to adjust processing capabilities based on inbound traffic Provides multiple specifications that you can specify based on the traffic peaks in your business
Cloud-Native Support Supports cloud-native services Serves as a cloud native gateway to distribute and mirror network traffic and supports canary release and blue-green deployment Supports cloud-native services
Scenarios Supports high concurrency to withstand Layer 4 traffic spikes
Serves as an ingress for IoT services such as Internet of vehicles (IoV)
Supports cross-zone disaster recovery and serves as an ingress for both on-premises and cloud services
Provides high-performance services and supports auto scaling at Layer 7
Maintains low network latency for audio and video applications that handle a large amount of network traffic
Supports canary release and blue-green deployment for cloud native applications
Distributes network traffic across backend servers at Layer 4 to ensure the high availability of websites and systems
Supports a large number of concurrent connections to backend servers
Provides intra-region and cross-region disaster recovery
Pricing NLB Pricing Details > ALB Pricing Details > CLB Pricing Details >
Getting started Create a NLB Create an ALB Create a CLB


Multiple Protocols

Supports multiple protocols to meet your business requirements in various scenarios.

Basic Protocols

Supports Layer 4 load balancing over TCP or UDP and Layer 7 loading balancing over HTTP or HTTPS

Advanced Protocols

Supports QUIC at the application layer. QUIC is an advanced protocol that improves transmission on audio, video, and mobile applications. ALB also supports gRPC, which facilitates efficient communication among microservices through API operations.

Multi-Level Disaster Recovery

Provides disaster recovery at multiple levels to ensure high availability.

Health Checks

Monitors the condition of backend servers regularly. SLB does not distribute network traffic to unhealthy backend servers to ensure availability.

Multi-Zone Deployment

Supports multi-zone deployment in specific regions to provide zone-disaster recovery.

Cluster Deployment and Session Synchronization

Server Load Balancer (SLB) supports cluster deployment and session synchronization. You can perform hot upgrades and monitor the health and performance of machines in real-time.

Secure and Reliable

Provides built-in security capabilities (free of charge) to secure transmission and reduce costs.

Layer 4 Security

Server Load Balancer (SLB) is resilient against DDoS, SYN flood, UDP flood, ACK flood, ICMP flood, and DNS flood attacks at Layer 4.

Layer 7 Security

Provides security capabilities at Layer 4 and Layer 7. Layer 7 supports the configuration read-only mode. You can integrate Server Load Balancer (SLB) with WAF to secure your applications.

Certificate Management

Provides certificate management for HTTPS requests to ensure the reliability and security of the transmission.

Flexible Scheduling

Supports multiple scheduling algorithms and forwarding methods to improve the application deployment flexibility.

Scheduling Algorithms

Supports Weighted Round Robin (WRR) and Weighted Least Connection (WLC). You can specify scheduling algorithms to distribute network traffic based on your business requirements.

Domain Name and URL Forwarding

Distributes network traffic across backend servers based on domain names and URLs. This improves the application deployment flexibility.

Flexible Management and Billing

Allows you to specify the instance type and billing method based on your business requirements. Alibaba Cloud also provides multiple methods to manage your Server Load Balancer (SLB) service.

Flexible Billing

Supports the pay-as-you-go and subscription billing methods and the pay-by-data-transfer and pay-by-bandwidth metering methods.

Flexible Management

You can create, configure, and manage Server Load Balancer (SLB) instances in the console by calling APIs in OpenAPI or using Alibaba Cloud SDKs.



Workloads on backend servers are heavy during peak hours in the audio, video, and game industries:

• A large amount of network traffic is forwarded between clients and backend servers in scenarios, such as short videos, long videos, livestreaming, online education, and online games.

• Large traffic fluctuations occur in audio and video scenarios. This affects the performance, elasticity, stability, and availability of systems.


  • High Performance

    Supports Cloud Network Management 2.0. A single SLB instance supports 1,000,000 QPS.

  • High Elasticity

    SLB automatically adjusts its processing capabilities based on the inbound traffic. You do not need to configure the service manually.

  • Advanced Protocol

    Supports QUIC to facilitate transmission for videos and reduce First Contentful Paint (FCP) time.

Alibaba Cloud CDN

A highly scalable and cost-effective service to accelerate content delivery.

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Automatically protects your service from DDoS attacks.

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ApsaraDB for Redis

A fully-managed cloud database service that supports Redis.

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Frequent business adjustment occurs in scenarios, such as new retail, new finance, product releases, and large-scale promotions.

Services must be secure, reliable, elastic, and ready to use after they are activated.

You must provide flexible billing to reduce costs.


  • Ready-to-use

    You do not need to purchase or deploy any hardware. The SLB service is ready to use after it is activated. You can specify billing methods based on your business requirements. This allows you to manage your business flexibly and efficiently.

  • Scalability

    SLB automatically adjusts its processing capabilities based on inbound traffic. You do not need to configure the service manually in large-scale promotion scenarios.

  • High Security and Reliability

    Provides disaster recovery at four levels. SLB supports integration with Anti-DDoS and Cloud Firewall to secure your business.

Elastic Compute Service (ECS)

Provides elastic and secure servers to host your services on the cloud.

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Web Application Firewall (WAF)

Defends websites from common attacks at the application layer to ensure security and availability.

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Cloud Enterprise Network (CEN)

A global network that consists of interconnected hybrid clouds and distributed systems.

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Enterprises from the Internet, finance, and enterprise sectors want to use advanced cloud-native technologies to deploy their new businesses on the cloud or adjust their current businesses.

You must use the cloud-native SLB service to use ACK, SAE, or Kubernetes.


  • Cloud-Native

    Integrated with ACK, SAE, and Kubernetes. SLB functions as a cloud-native gateway on Alibaba Cloud to distribute inbound network traffic.

  • Fully Developed APIs

    SLB supports gRPC and provides fully-developed APIs that you can call to manage the connections to a large number of microservices.

Container Service for Kubernetes (ACK)

Provides secure and highly-available container services and supports stable upgrades.

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Elastic IP Address (EIP)

An independent public IP resource that allows flexible management.

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NAT Gateway

Functions as an Internet gateway for a VPC.

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How It Works


Multinational enterprises want to distribute network traffic from different regions across applications and connect their data centers to Alibaba Cloud in a cost-effective way.

They want to build a hybrid cloud or a cross-region network that provides multi-level disaster recovery.


  • Support for All Regions

    Supports intelligent DNS resolution. Client traffic is directed to the best available IP addresses to accelerate transmission and improve the user experience.

  • Multi-Level Disaster Recovery

    SLB provides high availability across regions and zones.

  • Ease of Use

    You can use SLB and CEN to build a global network that connects data centers in different regions to Alibaba Cloud in a fast and simplified way.

Global Accelerator (GA)

Provides network acceleration services for your Internet-facing application globally.

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Cloud Enterprise Network (CEN)

Allows you to build a global network that consists of interconnected hybrid clouds and distributed systems with scalability and communication capabilities at the enterprise level.

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Object Storage Service (OSS)

Provides encrypted and secure storage services on the cloud.

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Product Updates

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