Outage report · Major outage

Zulip outage on Dec 18, 2023

DDoS attack on Zulip Cloud

SeverityMajor outage
StartedDec 18, 2023, 21:38UTC
ResolvedDec 19, 2023, 04:42UTC
Duration7h 4m

What happened

Zulip reported a major outage starting Dec 18, 2023, 21:38 UTC, affecting Zulip Cloud, Mobile Push Notification Service. It was marked resolved at Dec 19, 2023, 04:42 UTC.

  • The incident lasted 7h 4m from first report to resolution.
  • It was the longest significant outage Zulip reported in the 12 months up to it.
  • Zulip had reported no other partial or major outages in the 90 days before it.

Latest update from Zulip

This incident has been resolved.

Read Zulip's official incident report ↗

What our independent monitoring saw

Our independent monitoring of Zulip started after this incident, so this report is based on Zulip's status page.

Zulip's overall reliability

100.0/100

Zulip has a reliability score of 100.0/100, with 100% effective uptime and 0 incidents over the last 90 days.

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