Glossary · Monitoring

Brownout

A brownout is a partial service degradation in which a system still works but with reduced capacity, slower responses or disabled features.

Updated October 14, 2026

A brownout is a state between fully up and fully down. The service responds, but slowly, to only some users, or with some features switched off. The term is borrowed from electric power, where voltage drops without a total blackout.

Why it matters

Simple up/down checks miss brownouts, because the site returns 200 even while checkout times out for a share of users. They are also the usual lead-up to a full outage when load or errors keep growing. Teams sometimes cause them on purpose, shedding non-essential features to protect core ones during peak traffic or when deprecating an API.

Example

A shop's search is broken but browsing and checkout work. A basic ping stays green. A monitor that checks response time and verifies page content would show it:

check: GET /search?q=test
expect: status 200, body contains "results", time < 2s
actual: 200, time 14s, no results

Report it on your status page as degraded performance, not as operational.

Common mistakes

  • Only monitoring the homepage.
  • Alerting on availability and ignoring latency and error percentage.
  • Having no way to degrade deliberately, such as a flag that disables heavy features.

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