When was Claude Opus 5 released?

Claude Opus 5 was released on July 24, 2026, about eight weeks after Claude Opus 4.8, which itself had shipped on May 28, 2026 - a notably tighter release cadence than earlier Opus generations.

Its launch came alongside two other platform updates on the same day: mid-conversation tool changes, letting developers add or remove tools between turns without invalidating the prompt cache, and automatic fallbacks on the API, routing safety-classifier-flagged requests to another model instead of blocking them.

The release followed shortly after Claude Fable 5 and Claude Mythos 5, Anthropic's Mythos-tier models, which had themselves launched on June 9, 2026.

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