Models
Choosing Claude API models — model IDs and versioning, context windows and tokens, and model comparisons.
5 articles
Opus vs Sonnet: Opus 5.5 vs Sonnet 5 — Which Claude Model Should You Use?
Claude Opus 5 and Sonnet 5 differ in price, speed, context window, and thinking mode. Here's how to pick the right one in the API or the Claude.ai app.
Claude API Pricing by Model — Input/Output Token Rates and How to Cut Costs with Batch and Prompt Caching
Compare Claude API token pricing across Opus 5, Sonnet 5, Haiku 4.5, and Fable 5.1, and learn how Batch API's 50% discount and prompt caching's up to 90% discount can lower your costs.
Claude Model Comparison: Opus 5, Sonnet 5, Haiku 4.5, Fable 5.1
Compare specs and pricing for all four current Claude models (Fable 5.1, Opus 5, Sonnet 5, Haiku 4.5) and get clear selection criteria by task type, based on official docs.
Claude API Context Windows and Tokens: Limits and Management
What counts against the context window, what happens past the limit, and how to manage tokens with counting, max_tokens, and compaction.
Claude API Model IDs and Versioning: Aliases, Pinned Snapshots, and Migration
What goes in the Claude API model parameter? The difference between a pinned ID like claude-opus-5 and an alias like opus, why 4.6-generation dateless IDs are pinned too, pinning for production, planning for deprecation, and the Models API — all from the official docs.