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Claude Opus 4.1

Proprietary Anthropic · 2025-08-05 · Proprietary

Drop-in upgrade for Opus 4 released August 5 2025, same pricing and API surface. Anthropic flagged multi-file code refactoring and agentic search as the main improvements. Extended thinking budget of up to 64K tokens carries over from Opus 4.

Cost

— / Mtok input
— / Mtok output

Anthropic API · as of 2026-05-21

source ↗

Architecture

tokens in Embedding vocab not disclosed × N layers Architecture not disclosed (proprietary or undocumented) Output projection tokens out
Schema-generated from data/models.yaml. Every label is auditable against the model's sources.

Specs

Architecture
unknown
Total params
not disclosed
Active params
not disclosed
Context window
not verified
Attention
unknown
Position encoding
unknown
Post-training
rlhf, constitutional
OSI-approved
no
Data released
no
Training code
not released

Benchmarks

Each score carries the date it was published; we never infer or interpolate missing scores.

Code

SWE-Bench Verified 74.5 as of 2025-08-05 source ↗

Available quantizations

None. The weights are not distributed, so there are no public quantizations.

Notable innovations

  • · Multi-file refactoring gains over Opus 4
  • · Drop-in API replacement at same pricing

Lineage

Minor Opus refresh, same pricing and capabilities envelope.

Derived from

Claude Opus 4 2025-05-22

Derivatives

Sources