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Built for real engineering decisions

AI Model & API Guides

Source-linked guidance for AI models, API integration, and developer workflows—turning fast-changing prices, quotas, capabilities, and limits into decisions you can verify.
  • Primary sources first
  • Reproducible steps and failure boundaries
  • Volatile facts carry review dates
  • 466 articles
  • 6 languages
  • 12 topics
  • Updated Sep 25, 2026

Opus 5.5 and Fable 5.1 beside a checklist for choosing a model by accepted work
Claude Code

Claude Fable 5.1 vs Opus 5.5: Which Should You Use?

Opus 5.5 is the sensible starting point for most work. Fable 5.1 earns its premium when it solves problems that Opus still misses at higher effort—not simply because the job is long.

8 min
Two separate paths for estimating Opus 5.5 API cost and checking a Claude subscription limit reset
API Pricing & Plans

Claude Opus 5.5 Pricing and Limit Reset: What Each One Changes

Opus 5.5 is $4 per million input tokens and $20 per million output tokens on the standard Claude API. The new limit reset belongs to eligible Claude subscriptions; your Usage card shows which limit it restores.

7 min