Service-Level Objective (SLO)
An SLO is a measurable target for a service’s reliability or performance over a defined window.
What is Service-Level Objective (SLO)?
A service-level objective sets a target for an operational measure, such as successful request percentage or response latency. The team chooses the indicator, target, and evaluation window. Unlike a customer SLA, an SLO is a reliability goal that guides engineering decisions and may have no contractual remedy.
Example in SaaS
A SaaS sets a goal that 99.95% of valid API requests succeed over a rolling 30-day window. It separately targets a response-time threshold for interactive requests. Monitoring shows whether each objective is being met, while error-budget policies guide how urgently the team addresses reliability issues.
What to watch for
An objective without a clear indicator is hard to act on. Define what counts as a valid request, which errors are included, and whether all endpoints have comparable needs. A stricter target costs engineering effort and may not improve the customer’s important workflow. Atlassian’s explanation distinguishes objectives from indicators and agreements so teams can use the terms consistently.
Source and further reading
Related terms: Service-level indicator, Error budget.