ANTHROPIC RETIRED MODEL GUIDE
Claude Sonnet 4.5 (2025-09-29) API
Claude Sonnet 4.5 (2025-09-29) is currently retired. Do not use claude-sonnet-4-5-20250929 for new requests; choose a currently supported Anthropic model from Model Plaza.
Choosing and integrating
Claude Sonnet 4.5 (2025-09-29) API pricing breakdown
Claude Sonnet 4.5 (2025-09-29) is retired on LLMFly AI and has no active API rates. Choose an available replacement in the model catalog and check its prices.
Retirement status
As of October 5, 2026, the live Model Plaza no longer lists claude-sonnet-4-5-20250929. It is therefore absent from pricing, pricing calculators, and the model comparison selector.
Migration guidance
Do not replace the ID based on model names alone. Review the currently supported Anthropic catalog, then compare output quality, tool use, latency, and cost per completed task on your existing acceptance set.
- Find the retired model ID in configuration, databases, and environment variables.
- Validate the replacement with a small set of real requests first.
- Confirm error handling, budgets, and fallback policy before moving all traffic.
Why this page remains
Keeping the stable URL lets users of old links and configurations identify the retirement and find a migration path. The page does not show stale platform pricing or offer a calculator for this model.
Frequently asked questions
Can I still call this model?
No. LLMFly AI does not currently support this model, and it is not listed in the live Model Plaza.
Why is this page still available?
It records the retirement, preserves the exact model ID, and helps existing integrations migrate.
Which model should replace it?
Choose from the current Anthropic catalog and validate it on your workload; do not replace it by name alone.
Choose a currently supported Anthropic model
Open the Anthropic model catalog and confirm availability before migration testing.