{"id":455,"date":"2026-09-29T22:48:07","date_gmt":"2026-09-29T17:18:07","guid":{"rendered":"https:\/\/blogs.reskilll.com\/what-developers-building-claude-sonnet-5-5\/"},"modified":"2026-09-29T22:48:07","modified_gmt":"2026-09-29T17:18:07","slug":"what-developers-building-claude-sonnet-5-5","status":"publish","type":"post","link":"https:\/\/blogs.reskilll.com\/what-developers-building-claude-sonnet-5-5\/","title":{"rendered":"What Developers Are Building With Claude Sonnet 5.5"},"content":{"rendered":"<p><strong>TL;DR: Claude Sonnet 5.5, released September 28, 2026, is a faster, cheaper model built for well-scoped everyday work &#8211; fixing bugs, iterating on features, and creating polished documents, slides and spreadsheets. It runs 30%+ faster than Sonnet 5, costs up to 30% less per task, and holds pricing at $2\/$10 per million tokens with a 1 million token context window.<\/strong><\/p>\n<p><strong>Claude Sonnet 5.5<\/strong> is the second model in the Claude 5.5 family, arriving six days after Opus 5.5. For many developers it may become the daily driver because it hits most of Opus-level quality at a fraction of the cost.<\/p>\n<h2>What Sonnet 5.5 Is Best At<\/h2>\n<ul>\n<li><strong>Fixing bugs<\/strong> &#8211; fast, well-scoped debugging<\/li>\n<li><strong>Iterating on features<\/strong> &#8211; quick edit-and-run loops<\/li>\n<li><strong>Polished documents<\/strong> &#8211; clear writing, human-like tone<\/li>\n<li><strong>Slides and spreadsheets<\/strong> &#8211; with a strong eye for design<\/li>\n<\/ul>\n<h2>The Numbers That Matter<\/h2>\n<table>\n<thead>\n<tr>\n<th>Metric<\/th>\n<th>Value<\/th>\n<\/tr>\n<\/thead>\n<tbody>\n<tr>\n<td>Speed<\/td>\n<td>30%+ faster output than Sonnet 5<\/td>\n<\/tr>\n<tr>\n<td>Cost<\/td>\n<td>Up to 30% less per task<\/td>\n<\/tr>\n<tr>\n<td>Price<\/td>\n<td>$2 input \/ $10 output per M tokens<\/td>\n<\/tr>\n<tr>\n<td>Context<\/td>\n<td>1M tokens, up to 128K output<\/td>\n<\/tr>\n<tr>\n<td>Terminal-Bench 4.0<\/td>\n<td>70.6% (agentic coding)<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<h2>Why the Cheaper Model Is a Big Deal<\/h2>\n<p>Sonnet 5.5 nearly matches Opus 5.5 on several benchmarks while costing up to 30% less per task. On the agentic coding test, the cheaper model even edges ahead. For everyday development, that combination of speed and price is hard to beat.<\/p>\n<h2>A Note on Watermarking<\/h2>\n<p>Sonnet 5.5 writes more clearly and in a more human-like way, and it also includes invisible text watermarking &#8211; worth knowing if you publish AI-assisted content.<\/p>\n<h2>How to Use It Well<\/h2>\n<p>Give Sonnet 5.5 well-scoped tasks with clear acceptance criteria. Save open-ended, high-judgment problems for Opus 5.5. This split keeps your speed high and your bill low.<\/p>\n<h2>Put It to the Test<\/h2>\n<p>Hackathons are the fastest way to learn what a model can and cannot do. <a href=\"https:\/\/reskilll.com\/allhacks\/c\/ai\">Join an AI hackathon on Reskilll<\/a>, read the <a href=\"https:\/\/reskilll.com\/blogs\/how-to-win-hackathon-2026-complete-playbook\/\">winning playbook<\/a>, or browse <a href=\"https:\/\/reskilll.com\/allHacks\">all hackathons<\/a>.<\/p>\n","protected":false},"excerpt":{"rendered":"<p>Claude Sonnet 5.5 launched Sept 28, 2026 &#8211; 30% faster, up to 30% cheaper. Here is what it is best at: bug fixes, polished docs, slides and fast feature iteration.<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"site-sidebar-layout":"default","site-content-layout":"","ast-site-content-layout":"default","site-content-style":"default","site-sidebar-style":"default","ast-global-header-display":"","ast-banner-title-visibility":"","ast-main-header-display":"","ast-hfb-above-header-display":"","ast-hfb-below-header-display":"","ast-hfb-mobile-header-display":"","site-post-title":"","ast-breadcrumbs-content":"","ast-featured-img":"","footer-sml-layout":"","ast-disable-related-posts":"","theme-transparent-header-meta":"","adv-header-id-meta":"","stick-header-meta":"","header-above-stick-meta":"","header-main-stick-meta":"","header-below-stick-meta":"","astra-migrate-meta-layouts":"default","ast-page-background-enabled":"default","ast-page-background-meta":{"desktop":{"background-color":"var(--ast-global-color-5)","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""},"tablet":{"background-color":"","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""},"mobile":{"background-color":"","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""}},"ast-content-background-meta":{"desktop":{"background-color":"var(--ast-global-color-4)","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""},"tablet":{"background-color":"var(--ast-global-color-4)","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""},"mobile":{"background-color":"var(--ast-global-color-4)","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""}},"footnotes":""},"categories":[3],"tags":[],"class_list":["post-455","post","type-post","status-publish","format-standard","hentry","category-hackathons"],"yoast_meta":{"focuskw":"claude sonnet 5.5","metadesc":"Claude Sonnet 5.5 is 30% faster and up to 30% cheaper. 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