$ diff claude-fable-5-1 longcat-2-0
Claude Fable 5.1 vs LongCat-2.0
Values come from Claude Fable 5.1 and LongCat-2.0, where each is cited to its source. This page states no benchmark result and ranks neither model — it puts two published specifications next to each other. Where a lab has not published a figure, the row says so rather than guessing.
AnthropicClaude Fable 5.1
- context
- 1M
- weights
- closed
- $/M in
- $10
- $/M out
- $50
- context
- 1M
- weights
- open
- $/M in
- $0.3
- $/M out
- $1.2
What actually differs
- Context window
- Identical — both accept 1M tokens, so context length is not a reason to pick either.
- Input price
- LongCat-2.0 at $0.3/M against $10/M — 33.3× cheaper to feed. Standard rates: one of these labs also quotes a lower cached-input tier, which applies only when a prefix is reused — see the full spec below.
- Output price
- LongCat-2.0 at $1.2/M against $50/M — 41.7× cheaper to generate. Output dominates the bill on most agentic workloads, where the model writes far more than it reads.
- Weights
- LongCat-2.0 publishes weights (MIT (commercially permissive)); Claude Fable 5.1 is API-only. That decides self-hosting, air-gapped deployment and fine-tuning before any capability question does.
- Recency
- Claude Fable 5.1 shipped 63 days after LongCat-2.0 (2026-09-01 vs 2026-06-30).
Full spec
| Attribute | Claude Fable 5.1 | LongCat-2.0 |
|---|---|---|
| Developer | Anthropic | Meituan |
| Released | 2026-09-01 | 2026-06-30 |
| Context window | 1M tokens | 1 million tokens (LongCat Sparse Attention / LSA) |
| Pricing | $10/M input · $50/M output · cache reads $0.25/M | $0.30/M input · $1.20/M output ($0.006/M cached input) — OpenRouter catalogue, read 2026-07-28. Open weights, so this is hosted-inference pricing rather than a licence fee. |
| License | proprietary (API-only; no weight release) | MIT (commercially permissive) |
| Availability | Claude API as `claude-fable-5-1`; plan-tier access is disputed — see `## Conflicting Reports` | Open-sourced 2026-06-30; previously served on OpenRouter under the codename "Owl Alpha" |