Migrating off claude-mythos-5 — retirement date and replacement
Source last checked: 2026-09-21.
Anthropic is retiring claude-mythos-5 on 2027-06-09 — in 261 days. The provider has not named a replacement in its own documentation, so the migration target is your decision. This page is built from Anthropic’s official deprecation notice and is rechecked weekly; the source link is below.
When is claude-mythos-5 being deprecated?
| Model | Provider | Retires | Replacement |
|---|---|---|---|
| claude-mythos-5 | Anthropic | 2027-06-09 | — not named |
Source: Anthropic deprecation notice
Test before switching
- Check the replacement's supported API endpoints and request parameters.
- Test your prompts, structured output, streaming and tool calls on staging.
- Compare quality, latency, pricing and rate limits on your workload.
- Keep a rollback path while the old model remains available.
Download retirement dates for your models.
What should I migrate claude-mythos-5 to?
Anthropic has not published a successor for this model. That makes the decision yours, and it is worth treating as an opportunity to compare providers rather than defaulting to whatever is nearest. Endpoint responsiveness is measurable; model quality claims mostly are not.
Measured latency of the Anthropic API host
| Region | p50 TTFB | p95 | Uptime | Probes |
|---|---|---|---|---|
| Asia (Tokyo) | 228 ms | 281 ms | 100% | 287 |
| Europe (Germany) | 200 ms | 302 ms | 100% | 288 |
| South America (São Paulo) | 196 ms | 250 ms | 100% | 287 |
| US (Central) | 93 ms | 156 ms | 100% | 287 |
Edge latency to the provider’s API host over the last 24 hours, measured from 4 regions. This measures the endpoint, not the model: swapping models on the same host is not an inference benchmark or a promise about the replacement model. Compare edge latency →
What else retires on 2027-06-09?
| Model | Provider | Retires | Replacement |
|---|---|---|---|
| claude-fable-5 | Anthropic | 2027-06-09 | — not named |
Same shutdown date. If you call more than one of these, they are one migration, not several.
Other Anthropic models being retired
| Model | Provider | Retires | Replacement |
|---|---|---|---|
| claude-opus-4-1-20250805 | Anthropic | 2026-08-05 | claude-opus-4-8 |
| claude-opus-4-20250514 | Anthropic | 2026-06-15 | claude-opus-4-8 |
| claude-sonnet-4-20250514 | Anthropic | 2026-06-15 | claude-sonnet-4-6 |
| claude-3-7-sonnet-20250219 | Anthropic | 2026-02-19 | claude-sonnet-4-6 |
| claude-3-5-haiku-20241022 | Anthropic | 2026-02-19 | claude-haiku-4-5-20251001 |
| claude-3-haiku-20240307 | Anthropic | 2026-04-20 | claude-haiku-4-5-20251001 |
| claude-3-5-sonnet-20240620 | Anthropic | 2025-10-28 | claude-sonnet-4-6 |
| claude-3-5-sonnet-20241022 | Anthropic | 2025-10-28 | claude-sonnet-4-6 |
How is this calendar maintained?
Entries are pulled from provider documentation by an automated weekly job and every one carries a link to its source. Nothing is inferred from blog posts or social media. When a provider changes a date, the change appears here after the next run and is visible in the changelog. The full calendar across all providers is on the deprecations page, and this provider’s own list is at Anthropic deprecations.