Tutorials, deep dives and product notes — built for developers.
OpenAI's cheapest tier cut its price 61%, cut its hallucination rate from 93% to 77%, and lost a point on the independent index. Same-harness data on both generations, where Luna regressed, where it improved, and the ten-week price collapse.
Across all six effort levels, GPT-6 Sol scores within a point of GPT-5.6 Sol and costs about half as much per task. Same-harness data on both, the full effort ladder, where coding improved, where knowledge work regressed, and the November price cliff.
OpenAI shipped GPT-6 Sol 90 minutes after Claude Opus 5.5, at half the token price. Artificial Analysis ran both on the same tests: Sol is cheaper to any index score up to about 44, then runs out of headroom. Every benchmark, both effort ladders and the real bill.
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.
Opus 5.5 wins eight of the nine benchmarks Anthropic publishes against Fable 5.1 at 2.5x lower token price - but four of those margins sit inside the disclosed error bars. Includes the HAProxy same-task test, the 16-0 research-report result and the one-way thinking-block handoff.
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.
DeepSeek V4.1 Flash wins 5 of the 15 benchmarks it shares with Claude Opus 5 — by an average of 1.94 points, while undercutting it by up to 41.7× on output price. Opus 5's 10 wins average 10.19 points. Full vendor data, community test reports, pricing math, charts and a routing verdict.
Terminal-Bench 4.0 public board remains led by GPT-6 Astra (58.2%); Grok 4.7 is listed at 37.6% ±3.5 ($3.7k, 5.5B tokens). Separate, unranked runs: Anthropic Opus 5.5 66.4%, Cognition SWE-2 27.3%, and Artificial Analysis Codex runs GPT-6 Sol 44% / Luna 13%. Harness caveats included. Updated Sep 25, 2026.
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.
Gemini 3.8 Flash review: DeepSWE v1.1 (73.7%), Terminal-Bench 2.1 (89.4%), full benchmark comparison vs Claude Opus 5 & GPT-5.6 Sol, real Antigravity builds with live links, and 3.8 Flash Cyber breakdown.
Comprehensive comparison of GLM 5.3 vs Claude Opus 5 with interactive radar capability chart, direct score bars, token pricing, and benchmark analysis. Updated August 19, 2026.