Anthropic's Claude went down across every surface on April 28 between 17:34 and 18:52 UTC — about 78 minutes — taking out Claude.ai, Claude Code, Claude Chat, and the public API simultaneously. The first reports hit Downdetector around 10:59 a.m. PT and crossed 5,000 within 30 minutes; the peak passed 12,000 user reports. Anthropic's own status page escalated the event to a 'Major Outage' classification, the highest tier the company uses publicly. Users hit authentication errors on the web app and elevated failure rates through the API and Code, with workflows breaking mid-session. Service was confirmed restored by 12:02 p.m. PT.
The pattern matters more than the duration. A single underlying failure took down login, chat, the developer surface, and the IDE/CLI agent at the same time — meaning the auth and gateway layer, not a model-serving cluster, was the single point of failure. For agentic workflows that retry against the API, an 80-minute window is enough to corrupt long-running runs that don't checkpoint, and it's enough to trip every downstream alerting system that depends on Claude as a hard dependency.
This is the third notable Claude disruption in roughly a month and the second in two weeks. Anthropic has been aggressively expanding capacity through new compute deals — most recently Google's $40B commitment with 5GW of capacity attached — but capacity is not the same as reliability, and the public outages keep landing on the gateway and identity layer rather than the model layer. As Claude becomes a load-bearing dependency for tools like Claude Code, GitHub Copilot integrations, and enterprise agent platforms, the SLA conversation gets serious in a way it wasn't a year ago.
Takeaway for learners: if you're building anything on a frontier model API, treat single-vendor outages as a design constraint, not an edge case. Add a fallback model from a different provider, checkpoint long agent runs to disk, and keep your auth path independent of the model API where possible. The 78-minute Anthropic outage is your free reminder to test what your system does when its model dependency disappears.