What is Opus?

Opus is an AI model, likely a version of Anthropic’s Claude, discussed in relation to code generation, token efficiency, performance dynamics, and its use in multi-model systems.

• Dec 2025 - Tobi Lütke said Opus changed everything for his engineers, with many top engineers not writing code since that month.
• May 2026 - Gavin Baker stated that Claude on Opus generates 70% fewer tokens for the same question compared to other models.
• May 2026 - Krishna Rao observed Jevons paradox with Opus: lower price led to disproportionately higher consumption.
• Jul 2026 - Nathaniel Whittemore said Harvey and Fireworks pair an open weight GLM worker with an Opus advisor for legal tasks, seeing improved performance over Opus alone for a fraction of the cost.
• Jul 2026 - Jason Lemkin noted that when Claude on Opus talks to Replet on Sonnet for a big feature, Replet brings in a sub agent called the architect which runs on Codex on OpenAI.
• Jul 2026 - Alistair Pullen said Opus was in the region of 1.5 to 1.8 with around 150 billion active parameters.