The Security Capacity Unit (SeCU) resource plan is a cost-optimization solution for the pay-as-you-go edition of Web Application Firewall (WAF) 3.0. You can use it to offset your request processing fees and feature fees.
What are SeCU resource plans
SeCU
The total cost of the pay-as-you-go WAF 3.0 consists of request processing fee and feature fee. Both are measured in SeCU, our standard billing unit. For details on how the system calculates SeCUs, see Pay-as-you-go billing.
Price: The unit price of a SeCU is CNY 0.05.
Billing interval: The system measures SeCU usage hourly. For example, usage from 10:00:00 to 10:59:59 is calculated as one hour's worth of SeCU consumption.
Rounding rule: The system rounds SeCU usage up to the nearest integer. For example, if you use 0.5 SeCUs in an hour, the system bills you for 1 SeCU for that period.
SeCU resource plan
A SeCU resource plan is a prepaid package that offsets the total cost of the pay-as-you-go WAF 3.0.
Specifications: SeCU resource plans provide a 1:1 ratio for offsetting fees. For example, a resource plan with a 2,000 specification can offset the cost of 2,000 SeCUs. Larger specifications offer greater discounts.
Validity period: SeCU resource plans are valid for one month or one year.
For a one-month validity period, the following specifications are available: 2,000, 10,000, 100,000, 500,000, 1 Million, or 5 Million.
For a one-year validity period, the following specifications are available: 100,000, 500,000, 1 Million, 5 Million, 10 Million, or 50 Million.
Deduction rules: The system settles pay-as-you-go WAF fees daily and generates a bill the next day. A SeCU resource plan takes effect immediately after purchase, and the system prioritizes it for fee deductions. For example, if you purchase a resource plan on October 7, it offsets fees on bills generated on and after October 7.
Stacking rule: You can purchase multiple resource plans. If you have more than one plan of the same type, the plan that expires first is used first for deduction. If plans share an expiration date, the system uses the one purchased first.
Expiration rule: When a resource plan's quota is depleted or it expires, the system automatically switches to the pay-as-you-go model and deducts fees from your account balance.
Usage notes
Before you purchase and use a SeCU resource plan, ensure that you meet the following requirements:
You have activated a pay-as-you-go WAF 3.0 instance. If not, see Protect an ECS instance from HTTP flood attacks to activate an instance and add your website.
Your account does not have any overdue payments. You can only use a resource plan for deductions if your account is in good standing.
Recommendations
Recommended use cases
Stable business with predictable usage: Your website traffic and feature usage are relatively stable for at least the next month, so you can estimate your monthly SeCU consumption.
Not recommended for
Volatile and unpredictable business: Your business changes frequently, including the number of websites connected to WAF or the features you use, making it difficult to estimate SeCU usage.
Extremely low monthly usage: The minimum resource plan specification is 2,000. If your monthly SeCU usage is below this amount, you forfeit the unused quota.
Short-term testing or trials: You only plan to try WAF features for a short period.
Estimate your SeCU usage
Go to the Billing Management page to view your daily SeCU usage over the last seven days, or go to the Billing Details page to get complete SeCU usage information.
Estimate your monthly SeCU usage to help you choose the right resource plan specification. For example, the figure below shows that the usage in May 2025 was 13,406 SeCUs. If your request volume remains stable and you do not change your WAF and protection settings, your estimated monthly usage is approximately 13,000 SeCUs. You can purchase one 10,000 and one 2,000 specification resource plan, and select Validity Period as 1 Month.
On the Billing > Bill Details page of Alibaba Cloud, set Bill Month to the target month and filter Product Name by Web Application Firewall 3.0 (Pay-as-you-go) to view the SeCU usage for the current month in the Usage column.
Purchase a SeCU resource plan
Go to the WAF 3.0 SeCU Resource Plan buy page.
Select the Resource Plan Specification, Quantity, and Validity Period.
Review your configuration, click Buy Now, and complete the payment. The resource plan takes effect immediately without further configuration.
Manage SeCU resource plans
View the remaining quota
Go to the Resource Plan page, set Resource Dimension to Resource package, and click the Instance Summary tab.
Find the resource plan with WAF 3.0 SeCU Resource Plan as the product name. Check the Total and Remaining fields to view usage. If the Remaining is less than the Total, it means the plan has been used for deductions.
Set alerts for remaining quota
To receive notifications when your resource plan quota is low, click Set Remaining Quota Alert in the upper-right corner of the Resource Plan to configure alerts.
Unsubscribe from a resource plan
Resource plans do not support self-service unsubscription. If you purchased a plan within the last five days and have not used it, you can submit a ticket to request a refund.
FAQ
Do I need to purchase a SeCU resource plan together with a pay-as-you-go WAF instance?
Yes. A SeCU resource plan is not a WAF instance extension. It is designed exclusively to offset the fees of the pay-as-you-go WAF 3.0. You must first purchase a pay-as-you-go WAF instance to use the SeCU resource plan. If you only purchase a SeCU resource plan or only have a subscription-based WAF instance, the resource plan will not take effect. On the WAF 3.0 purchase page, Product Type provides two independent options: Web Application Firewall 3.0 and WAF 3.0 SeCU Resource Plan, which can be purchased separately. After selecting Web Application Firewall 3.0, set Billing Method to Pay-as-you-go, select Chinese Mainland or Outside Chinese Mainland for Region, and set WAF Edition to Pay-as-you-go 3.0.
Why did I receive a pay-as-you-go bill after purchasing a SeCU resource plan?
Pay-as-you-go WAF fees are settled daily. The SeCU resource plan takes effect immediately after purchase and deducts fees from the bill generated the next day.
For example, if you purchase a resource plan on October 7, the plan offsets the fees for October 7 and subsequent days. However, you will still receive pay-as-you-go bills for usage from October 1 to October 6.