Tutorials, deep dives and product notes — built for developers.
GPT-6.1 Terra vs Claude Sonnet 5.5: Terra is ahead at low and medium effort, then Sonnet pulls 7.9 points ahead at max while costing 19× more per task ($7.60 vs $0.40). Full effort-ladder comparison, vendor and independent benchmarks, hallucination rates, and a routing guide.
GPT-6.1 Sol vs GPT-6.1 Terra: Terra costs half as much per token and 1.8× to 2.6× less per Artificial Analysis task at matched effort, while Sol scores 3.7 to 6.5 points higher. Effort-by-effort cost and score comparison, vendor and independent benchmarks, accuracy trade-offs, and a routing guide.
GPT-6.1 Sol replaced GPT-6 Sol after seven days: +4 index points, +12 on Terminal-Bench 4.0, and a cache rate halved to $0.10. It also dropped the "none" reasoning setting, uses 10-30% more output tokens, and is measurably slower.
GPT-6.1 Sol matches Claude Opus 5.5's default index score for 46% less per task and ties it at low effort for 76% less — then stops at index 52, below every Opus effort above default.
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.