The Ur-model Cometh

Hello, and happy Sunday! This past week was like Christmas in February. Anthropic and OpenAI both dropped significantly improved models that moved us closer to peak general-purpose AI, and it was all-hands here at Every to share what our advance testing revealed about each of them. The result was Vibe Checks on both Opus 4.6 and Codex 5.3, the inevitable head-to-head showdown, and a livestream featuring Sam Altman himself.—Kate Lee

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Knowledge base

“GPT-5.3 Codex vs. Opus 4.6: The Great Convergence” by Dan Shipper/Vibe Check: Opus picked up Codex’s precision. Codex gained Opus’s warmth and willingness. Every CEO Dan Shipper and the team tested both extensively, and the verdict is that these models are—in a good way—beginning to resemble each other. Most of the Every team is now using both. Read this for the full head-to-head breakdown, including which one has the higher ceiling and which delivers steadier, faster autonomous execution.

“Vibe Check: Opus 4.6—The Best Coding Model We’ve Tested (With Some Maddening Habits)” by Dan Shipper and Katie Parrott/Vibe Check: In 15 minutes, Opus 4.6 solved a Monologue iOS problem that stumped both Codex and Opus 4.5—researching competitors and open-source repos to find the perfect solution. Put simply: It’s extremely smart. As proof, it set the high score on Cora general manager’s Kieran Klaassen’s LFG benchmark. Some trade-offs exist, though—it’s slower and occasionally confabulates, and the team preferred Opus 4.5’s prose in blind tests. But for vibe coders? Switch now. Read this to learn why.