Claude Fable 5 vs GLM-4.5
Anthropic Claude Fable 5 | Z.ai GLM-4.5 | |
|---|---|---|
| Overview | ||
| Company | Anthropic | Z.ai |
| Release date | Jun 9 2026 | Jul 28 2025 |
| Access | Proprietary | Open Weight |
| Specifications | ||
Parameters | — | 355B |
Context window | 1M | 128k |
| Benchmarks | ||
Nonsense detection BullshitBench v2Given a confidently-worded but nonsensical prompt, does the AI spot that it makes no sense and push back — instead of playing along and inventing an answer? The score is how often it clearly called out the nonsense. Higher is better. | 56% | — |
Agentic coding SWE-Bench ProCan the AI fix real bugs in real software? It's handed actual problems from open-source projects and has to write code that genuinely solves them. Higher is better. | 80.3% | — |
Coding SWE-Bench VerifiedReal coding tasks pulled from open-source projects — the AI has to find and fix actual bugs. A human-checked version of the original SWE-Bench. Higher is better. | 95.5%Best | 64.2% |
Agentic terminal coding Terminal-Bench 2.1Can the AI work in a command-line terminal — running commands and finishing technical setup tasks the way a developer would? Higher is better. | 88% | — |
Science GPQA DiamondGraduate-level science questions in biology, physics, and chemistry — hard enough that subject-matter PhDs score around 65%. Higher is better. | — | 79.1% |
Agentic computer use OSWorld-VerifiedCan the AI actually operate a computer — clicking, typing, and using real apps — to finish tasks on its own? Higher is better. | 85% | — |
Knowledge work GDPval-AAMeasures how well the AI does economically valuable knowledge work, judged against human experts. Shown as a rating (like a chess Elo) — higher is better. | 1932 | — |
| Timeline | ||
| Release gap | GLM-4.5 shipped 316 days before Claude Fable 5 | |
Which is better: Claude Fable 5 or GLM-4.5?
Claude Fable 5 leads GLM-4.5 on 1 of the 1 benchmark they both report (SWE-Bench Verified). GLM-4.5 shipped 316 days before Claude Fable 5, so benchmark comparisons should account for the intervening progress.
Context windows are 1M (Claude Fable 5) vs 128k (GLM-4.5). Claude Fable 5 is proprietary, while GLM-4.5 is open weight.
On SWE-Bench Verified, Claude Fable 5 leads at 95.5% vs GLM-4.5 at 64.2%.
Frequently asked questions
Claude Fable 5 was released by Anthropic on Jun 9 2026.
GLM-4.5 was released by Z.ai on Jul 28 2025.
Claude Fable 5 leads on SWE-Bench Verified — Claude Fable 5 95.5% vs GLM-4.5 64.2%.
Claude Fable 5 has a 1M context window; GLM-4.5 has 128k.
Claude Fable 5 is a proprietary model released by Anthropic. GLM-4.5 is an open weight model released by Z.ai.