--- title: Opus 4.6 and Codex 5.3 | daily.dev description: Anthropic released Claude Opus 4.6 and OpenAI released GPT-5.3-Codex within 15 minutes of each other. Both models are highly capable, though the improvements... canonical: https://daily.dev/posts/opus-4-6-and-codex-5-3-4ynvsyxn5 twitter:card: summary_large_image twitter:site: @dailydotdev og:type: website og:site_name: daily.dev og:title: Opus 4.6 and Codex 5.3 | daily.dev og:description: Anthropic released Claude Opus 4.6 and OpenAI released GPT-5.3-Codex within 15 minutes of each other. Both models are highly capable, though the improvements... og:url: https://daily.dev/posts/opus-4-6-and-codex-5-3-4ynvsyxn5 og:image: https://api.daily.dev/og/posts/4YnVsyXN5.png og:image:alt: Opus 4.6 and Codex 5.3 og:image:width: 1200 og:image:height: 630 og:locale: en --- > ## Documentation Index > Fetch the complete documentation index at: https://daily.dev/llms.txt > Use this file to discover all available pages before exploring further. # Opus 4.6 and Codex 5.3 **[Tech Lead Digest](https://daily.dev/sources/techleaddigest)** · 1 min read · 0 upvotes · 0 comments ## Summary Anthropic released Claude Opus 4.6 and OpenAI released GPT-5.3-Codex within 15 minutes of each other. Both models are highly capable, though the improvements over their predecessors (Opus 4.5 and Codex 5.2) are incremental rather than transformative. The most notable demonstration of the new capabilities is Anthropic's work on building a C compiler using parallel Claude agents, similar to Cursor's FastRender project. ## Full article daily.dev links to this article rather than hosting it. Read it at the original source: ## Similar posts on daily.dev - [Anthropic’s New Claude Opus 4.5 Reclaims the Coding Crown](https://daily.dev/posts/anthropic-s-new-claude-opus-4-5-reclaims-the-coding-crown-swsygmrln) · The New Stack · 1 upvotes · 0 comments --- Tags: [#ai](https://daily.dev/tags/ai), [#llm](https://daily.dev/tags/llm), [#c](https://daily.dev/tags/c), [#openai](https://daily.dev/tags/openai), [#anthropic](https://daily.dev/tags/anthropic) [View this post on daily.dev](https://daily.dev/posts/opus-4-6-and-codex-5-3-4ynvsyxn5) ```json {"@context":"https://schema.org","@graph":[{"@type":"Organization","@id":"https://daily.dev/#organization","name":"daily.dev","url":"https://daily.dev","logo":{"@type":"ImageObject","url":"https://daily.dev/apple-touch-icon.png","width":180,"height":180},"sameAs":["https://twitter.com/dailydotdev","https://github.com/dailydotdev","https://www.linkedin.com/company/daily-dev-ltd"]},{"@type":"WebSite","@id":"https://daily.dev/#website","url":"https://daily.dev","name":"daily.dev","publisher":{"@id":"https://daily.dev/#organization"},"potentialAction":{"@type":"SearchAction","target":{"@type":"EntryPoint","urlTemplate":"https://daily.dev/search?q={search_term_string}"},"query-input":"required name=search_term_string"}}]} {"@context":"https://schema.org","@type":"TechArticle","headline":"Opus 4.6 and Codex 5.3","url":"https://daily.dev/posts/opus-4-6-and-codex-5-3-4ynvsyxn5","mainEntityOfPage":{"@type":"WebPage","@id":"https://daily.dev/posts/opus-4-6-and-codex-5-3-4ynvsyxn5"},"datePublished":"2026-02-15T19:20:00.653Z","dateModified":"2026-02-15T19:20:20.284Z","description":"Anthropic released Claude Opus 4.6 and OpenAI released GPT-5.3-Codex within 15 minutes of each other. Both models are highly capable, though the improvements...","image":"https://media.daily.dev/image/upload/f_auto,q_auto/v1/posts/646733c382917ab1a862ebbac263dd17?_a=AQAEunF","thumbnailUrl":"https://media.daily.dev/image/upload/f_auto,q_auto/v1/posts/646733c382917ab1a862ebbac263dd17?_a=AQAEunF","isAccessibleForFree":true,"articleSection":"Tech Lead Digest","inLanguage":"en","publisher":{"@type":"Organization","name":"daily.dev","url":"https://daily.dev","logo":{"@type":"ImageObject","url":"https://daily.dev/apple-touch-icon.png","width":180,"height":180}},"author":{"@type":"Organization","name":"Tech Lead Digest","logo":"https://media.daily.dev/image/upload/t_logo,f_auto/v1/logos/6ed1ee1a2e5c49f698265a6b2912b80d","url":"https://daily.dev/sources/techleaddigest"},"commentCount":0,"discussionUrl":"https://daily.dev/posts/opus-4-6-and-codex-5-3-4ynvsyxn5","interactionStatistic":[{"@type":"InteractionCounter","interactionType":{"@type":"LikeAction"},"userInteractionCount":0},{"@type":"InteractionCounter","interactionType":{"@type":"CommentAction"},"userInteractionCount":0}],"keywords":"ai,llm,c,openai,anthropic","timeRequired":"PT1M"} {"@context":"https://schema.org","@type":"BreadcrumbList","itemListElement":[{"@type":"ListItem","position":1,"name":"Home","item":"https://daily.dev"},{"@type":"ListItem","position":2,"name":"Tech Lead Digest","item":"https://daily.dev/sources/techleaddigest"},{"@type":"ListItem","position":3,"name":"Opus 4.6 and Codex 5.3"}]} ```