Tutorials, deep dives and product notes — built for developers.
Opus 5.5 matches GPT-6 Astra on Terminal-Bench 4.0 for roughly 40% of the cost per task, with 5x cheaper cache reads. Astra keeps uncontested leads in science, maths and gated offensive security — and OpenAI says it is harder to monitor.
Anthropic's Claude Opus 5.5 matches Fable 5.1 on most work at $4/$20 per million tokens: 66.4% on Terminal-Bench 4.0, 1,846 GDPval-AA Elo, and 40% lower cost per task than Opus 5. Full benchmark table with footnotes, real tester results, the four breaking API changes, and where GPT-6 Astra still wins.
OpenAI's GPT-6 Astra vs Anthropic's Claude Fable 5.1: every benchmark, the independent indices, real-world head-to-heads, pricing deep dive, and who actually wins your workload.
GPT-6 Astra review: every benchmark, what people built, pricing, and the Critical cybersecurity rollout — with sources.
SWE-bench Pro: Anthropic-reported Opus 5.5 leads at 89.9%; newly tracked vendor results include Ornith-1.5-397B (65.1%) and Qwen3.8-Omni-Flash (63.3%), kept distinct from Scale standardized results. Updated October 9, 2026.