miji.beA URL shortener SLA (Service Level Agreement) is an agreement document that sets out the quality standards, such as uptime, response time, and data retention period, that a service provider guarantees to its users. For business use, the content of the SLA is one of the criteria for choosing a service.
An SLA defines three main metrics. The first is the uptime guarantee: at 99.9%, annual downtime comes to about 8.7 hours, and at 99.99%, about 52 minutes. The second is redirect response time, which is defined with values such as P95 (95th percentile). The third is the data retention period, which guarantees how long the short URLs you create will keep working.
Compensation for SLA violations includes service credits (discounts on future usage fees). For example, under the Amazon CloudFront SLA (as of May 2022), if monthly uptime falls below 99.9%, 10% of the usage fees is credited; below 99.0%, 25%; and below 95.0%, 100%. SLAs commonly set out exclusion conditions, and you need to check the text of each service's SLA to see what is excluded.
When choosing a URL shortener, you should check not only the SLA figures but also the measurement method (external or internal monitoring), the transparency of outage reporting (whether there is a status page), and the history of past incidents. It is also important to check whether the free plan has an SLA and, for business-critical uses, to decide on adoption after closely examining the SLA of the paid plan.