Claude Fable 5.5 (Leaked Checkpoint) vs DeepSeek V4.1 Flash
A direct, empirical evaluation of Claude Fable 5.5 (Leaked Checkpoint) (Anthropic) against DeepSeek V4.1 Flash (DeepSeek-AI).
Claude Fable 5.5 (Leaked Checkpoint)
Developed by Anthropic · Proprietary Frontier Dynamic Reasoner parameters
Terminal-Bench 4.0 autonomous shell execution (78.5% target), recursive self-critique, and 1.5M-token repository refactoring.
DeepSeek V4.1 Flash
Developed by DeepSeek-AI · 552B parameters
High-throughput software engineering, autonomous coding loops, terminal agents, 1M long-context retrieval, and low-cost production inference.
| Metric | Claude Fable 5.5 (Leaked Checkpoint) | DeepSeek V4.1 Flash |
|---|---|---|
| SWE-bench Verified | 84.2% | 67.2% |
| MMLU-Pro | 94.6% | 78.4% |
| MATH-500 | 98.4% | 92.6% |
| Context Window | 1,500,000 tokens | 1,000,000 tokens |
| Input Pricing (per 1M) | $3.50 | $0.06 |
| Output Pricing (per 1M) | $17.50 | $0.22 |