Simple Application Server (SAS) and Elastic Compute Service (ECS) are both compute services on Alibaba Cloud, but they serve different audiences and workloads. SAS is designed for individuals who want to get a server running in minutes — networking, billing, and images are preconfigured. ECS gives you full control over instance types, network topology, billing methods, and scaling strategies.
Use this page to decide which service fits your scenario.
Product comparison
| Feature | Simple Application Server (SAS) | Elastic Compute Service (ECS) |
|---|---|---|
| Target audience | Individual developers and students | Individuals or businesses with technical expertise |
| Typical use cases | Lightweight apps with low traffic: website building, knowledge and productivity management, cloud-based learning environments, e-commerce sites, forums and communities, and development environment setup | All business scenarios. Typical use cases: general web applications, online gaming, big data analytics, and deep learning |
| Advantages | Quick start: Application Images and System Images let you deploy a website or operations environment in minutes. Domain Name Resolution and HTTPS encryption are integrated out of the box. Predictable costs: Resources are bundled in fixed plans, so you always know what you'll pay. Simple management: Built-in tools cover Remote Logon, Server Monitoring, Firewall Configuration, Data Backup and migration, Application Management, and Operation Logs. Scalable: Upgrade to a higher-spec plan at any time, or migrate your data to an ECS instance when your needs outgrow SAS. | Wide selection of instance types with flexible resizing for different scenarios. Multiple billing methods. Extensive APIs. Scale instances, bandwidth, and Cloud Disks up or down at any time. Comprehensive security features and industry-specific solutions. |
| Limitations | Does not support installing virtualization software or enabling Nested Virtualization. Does not support sound card applications. Only one Data Disk can be attached. IPv6 address configuration is not supported. Advanced ECS features — including deployment sets, Resource Orchestration, Auto Scaling, and Resource Groups — are not available. Internal network connectivity has restrictions; see Regions and network connectivity. For the full list, see Limitations. | Nested Virtualization is supported only on Elastic Compute Service Bare Metal Instances and Super Computing Clusters. Does not support sound card applications. For the full list, see ECS limitations. |
| Billing | Plans and Data Disks are available on a Subscription basis only. Traffic that exceeds the plan quota is billed on a pay-as-you-go basis. | Supports Subscription, pay-as-you-go, and Preemptible Instance billing methods. The pay-as-you-go method can be combined with Reserved Instance Vouchers, Savings Plans, and Storage Capacity Units (SCUs) to balance cost optimization and flexibility over the long term. |
| Network | Virtual Private Cloud (VPC) resources are created automatically. A public IP address is assigned at instance creation and cannot be changed. Bandwidth is defined by the plan and cannot be customized. A built-in firewall controls network access. Internal network communication is supported; see Manage VPC connections. | Full control over network design for complex requirements: plan private networks using VPC and vSwitches, control traffic with Security Groups and network ACLs, and connect to the internet using Elastic IP Addresses (EIPs) and NAT Gateways. |
| Images | Only supports Application Images and System Images provided by the service, and Custom Images created from SAS instances | Supports Public Images, Custom Images, Shared Images, and Marketplace Images |
When to consider ECS
SAS handles most lightweight hosting needs well. Switch to ECS when your requirements include any of the following:
Specialized instance types — Your workload needs general-purpose, compute-optimized, big data, GPU, FPGA, or NPU instances, or Elastic Compute Service Bare Metal Instances. SAS does not offer these instance types.
High-concurrency or resource-intensive applications — Video transcoding, large-scale games, or complex distributed cluster applications require more compute resources and flexibility than SAS plans provide.
Full network control — You need to configure VPC topology, Security Groups, network ACLs, Elastic IP Addresses, or NAT Gateways to meet compliance or architecture requirements.
Advanced scaling and orchestration — You need Auto Scaling, deployment sets, Resource Orchestration, or Resource Groups to manage infrastructure programmatically.
Flexible billing — Your cost model requires mixing billing methods or using Reserved Instance Vouchers, Savings Plans, or SCUs.
For ECS instance type options, see ECS instance type families.
FAQ
Can I move my SAS server to ECS later?
Yes. Upgrade to a higher-spec SAS plan at any time from the console. When you're ready for ECS, migrate your server data to an ECS instance for more flexible resource configurations.
What happens if my SAS server exceeds the plan's traffic quota?
Traffic within the plan is included in the fixed price. Traffic beyond the quota is charged on a pay-as-you-go basis.
Does SAS support IPv6?
No. SAS does not support IPv6 address configuration. If IPv6 is required, use ECS.
Can I attach multiple disks to a SAS instance?
SAS supports attaching one Data Disk per instance. If your application requires multiple disks, use ECS.