Claude Opus 4.8 was Anthropic's flagship before Claude Fable 5 and Mythos 5 launched in June 2026. Millions of developers still run Opus 4.8 in Claude Code, API pipelines, and enterprise deployments — and it remains excellent.
Opus 4.8 strengths
Best-in-class coding and long-form writing, 200K+ token context, mature SDK patterns, and predictable refusal behavior teams already understand. Claude Code workflows built on Opus 4.8 are battle-tested.
Where Fable 5 pulls ahead
1M context windows, 128K output (vs 64K), task budgets, programmatic tool calling, compaction, and stronger multi-hour agentic sessions. For new projects starting June 2026, Fable 5 is the default upgrade path.
Should you migrate now?
Migrate when you hit context limits, need longer agent runs, or want task-budget cost controls. Stay on Opus 4.8 if your pipeline is stable and migration cost outweighs benefits. Run both in parallel during transition.
Pricing snapshot
API: approximately $15/$75 per million input/output tokens — higher than Fable 5. Consumer Claude Pro ($20/mo) includes Opus-tier access depending on your plan.
