What is the best replacement for Claude 4 Opus?

Claude Opus 4.8 is the direct replacement — same API, same quality, 67% cheaper ($5/$25 vs $15/$75 per million tokens) with 5x the context window (1M vs 200K). If you want to explore other providers, GPT-5 ($1.25/$10) and Gemini 3.1 Pro ($2/$12) are strong alternatives.

What should I replace Claude Sonnet 4.6 with?

Claude Sonnet 4.6 is the drop-in replacement at the same price ($3/$15). If you're open to switching providers entirely, GPT-5 ($1.25/$10) is 58% cheaper on input tokens, and Gemini 2.5 Flash-Lite ($0.10/$0.40) is 97% cheaper for budget workloads.

How do I migrate from Claude 4 to a new model?

For Claude Opus 4.8 or Sonnet 4.6: change the model name string in your code (one line). Your API key, SDK, and endpoint stay the same. For other providers: update the API base URL, authentication, and model name. Most teams complete migration in under an hour.

Will Claude 4 stop working on June 15?

Yes. After June 15, 2026, API calls to 'claude-4-opus' and 'claude-sonnet-4' return errors. Your API key will still work — you just need to update the model name string to the replacement model.