API / Application Error Rate
Percentage of API calls or user actions that result in an error response
What is API / Application Error Rate?
API or application error rate is the percentage of requests that return an error. It shows how reliably a system is serving its users.
Errors mean failed actions for users, so this is a core measure of software quality and health.
How this KPI is measured
- Function
- Product & Engineering
- Sub-function
- Infrastructure & Reliability
- Industry
- All Industries
- Type
- Lagging
- Impact
- Quality
- Unit
- %
- Measurement frequency
- Daily / Weekly
- Formula
- (Error responses / Total requests) × 100
How to calculate it
Divide error responses by total requests, and multiply by 100.
For example, if a service handled 5,000,000 requests and 15,000 returned errors, the rate is 0.3%.
Distinguish server errors, which are your fault, from client errors, and set alerts for sudden increases so problems are fixed quickly.
Where it is used
Monitoring system health
Detect problems early.
Guiding engineering priorities
Fix the biggest sources of errors.
Setting reliability targets
Agree service levels.
How to improve it
Tips and common mistakes
- Separate server errors from client errors.
- Look at errors by endpoint.
- Set targets that reflect user impact.
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