xAI’s Fastest Opus-Class Model
Opus-class output for coding, 3D, and agentic builds — at flash speed and a fraction of the token cost. Put it to work in your browser, no setup required.
Model preset to Grok 4.5 · Sign up to unlock more models
The hottest practices from the X community — what people are actually building with Grok 4.5: games, 3D worlds, simulations, renders and websites.
Built a beautiful Three.js solar-system and universe simulation from a single prompt — sped-up adjustable time, realistic orbits, stars, and a styled HUD.
Apply to see the full prompt and try it
Make a beautiful simulation of the universe and solar system. It should be sped up with adjustable time, realistic motion, orbits, stars. Use three.js. Make the HUD well styled and conform to modern design principles.
Gave four models the same task — three HTML5 canvas physics demos. Grok 4.5 handled all three well, got close to GPT-5.6, and ran on the free tier.
Apply to see the full prompt and try it
Build three self-contained HTML5 canvas scenes with real physics demos: 1) a robot deathmatch, Tombstone vs Minotaur; 2) a hydraulic press flattening stuff on a conveyor; 3) a semi truck jumping a canyon.
A real-time speed demo: Grok 4.5 streams a full single-file speed-demo.html live in the chat, showing how fast it codes.
Apply to see the full prompt and try it
Speed demo. Rules: 1) Write everything in the chat as you go — I want to watch the code appear on screen. 2) Do not use file-write tools first; stream the full file contents here as markdown code blocks. 3) No long preamble; start coding in the first message. Task: create a complete single-file speed-demo.html (HTML+CSS+JS, no external libs) with a dark, polished UI and a live stopwatch.
Grok 4.5 vs GLM 5.2 vs Gemini 3.1 Pro on one prompt — a 3D HTML solar system with orbit paths and a 2000–2026 timeline. Grok was among the winners.
Apply to see the full prompt and try it
Recreate our solar system with orbit paths + timeline from 2000 to 2026 as a single visually appealing 3D HTML file.
Shipped a playable FPS game in under an hour: Grok 4.5 wrote a game design document, pulled free assets, drafted a phased TODO, then looped through implementation.
Build with Grok 4.5Used Grok 4.5 in Cursor early access to brainstorm → plan → implement an Act 1 boss fight. His take: "feels like Opus 4.8 at 2x the speed at a much cheaper price point."
Build with Grok 4.5Calls Grok Build the most complete coding-agentic workflow yet — with built-in image generation and image-to-video, fast output, and quality he rates on par with Codex.
Build with Grok 4.5Built a full cyberpunk street in Unreal Engine 5.8 — neon, rain, signage and crowds — end-to-end with Grok 4.5 + Grok Build. Reportedly 10.75M tokens, 36.5 minutes, ~$12.40 API.
Build with Grok 4.5Powered a 3D Home Plan Builder with Grok 4.5 + Grok Imagine — designed a complete 2D + 3D floor plan inside the app in under a minute, at a fraction of Opus cost.
Build with Grok 4.5Built a beautiful website about black holes with Grok 4.5 — a quick showcase of how capable it is at designing and coding polished web pages.
Build with Grok 4.5Built a space-battle game with Grok 4.5 in Grok Build from a two-line prompt — it researched the idea, integrated a free low-poly ship, and even added sound effects.
Build with Grok 4.5Same challenge as Fable 5 — one prompt + one reference image to rebuild a Three.js 3D globe dashboard. Lighting, glass and depth matched on the first try; beats Opus 4.8 on this task.
Build with Grok 4.5Made a game with Grok 4.5 and added PS4 controller support — sketching a projector-based, warp-enabled world-heritage tour as the next step.
Build with Grok 4.5In a sealed benchmark, Grok 4.5 one-shot a locked-spec 3D scene in 3 minutes with every test green — matching numbers a 3-week hand-tuned build hit.
Build with Grok 4.5A polished one-shot build with Grok 4.5 — noticeably stronger coding than earlier versions.
Build with Grok 4.5A side-by-side comparison of GPT-5.6 Sol and Grok 4.5 on the same website-build prompt.
Build with Grok 4.5Asked Grok 4.5 for a photorealistic browser-based 3D city walkthrough — generated in about 10 minutes and rendered with 3D Gaussian Splatting.
Build with Grok 4.5Calls Grok 4.5 in Grok Build a generational leap — one-shot Three.js with thorough game mechanics added unprompted, faster than expected.
Build with Grok 4.5Made a Fall Guys–style 3D obstacle course in a single Happycapy session. He described the vibe; Grok 4.5 pulled free assets and returned a fully playable course — controls, checkpoints, finish line — incredibly fast.
Build with Grok 4.5Built a 3D lava-lamp simulator with convincing viscous fluid and lighting in ~15 minutes — praising its UI/UX sense, multiplied speed, and gentle token use.
Build with Grok 4.5Drove Blender through MCP with Grok 4.5 to create a magic-circle scene with explosion and water simulation effects.
Build with Grok 4.5We gave Grok 4.5 our agent-native computer and asked it to build something fully interactive. See what happened.
Grok 4.5 is a large language model from xAI, the successor in the Grok 4 line. It is positioned as an “Opus-class” model — comparable in output quality to top frontier models for coding and agentic work — while running noticeably faster and using tokens more efficiently, which makes long, autonomous agent runs practical and affordable.
On Happycapy, Grok 4.5 isn’t just a chat box. It powers an agent inside a secure cloud sandbox that can write code, run it, render 3D, drive tools, and deliver finished work — all from a single prompt, with no local setup.
Grok 4.5 compared with Fable, GPT 5.5, Claude Opus, GLM and others across DeepSWE, SWE Marathon, Terminal Bench 2.1, and SWE Bench Pro. Switch tabs to see each eval.
Eval created by Datacurve, run with each model provider's harnesses by AA
Competitor figures are drawn from the respective developers’ published system cards or benchmark leaderboards.
Source: xAI — Grok 4.5
No API keys. No setup. Just open a browser and start building.
Use millions of built-in skills to generate websites, presentations, spreadsheets, videos, games, and more.
From a single prompt to websites, documents, images, apps, and automations.
Long, multi-step build loops — write a spec, plan phases, then implement and iterate. Community demos span full games, apps, and tools built end-to-end.
Physics-flavored simulations, Unreal Engine scenes, Blender-via-MCP effects, and browser 3D (including Gaussian Splatting) from natural-language prompts.
Go from idea to a working, interactive artifact fast — makers report finished demos in 10–60 minutes.
Positioned as Opus-class quality with notably higher speed and strong token efficiency, which keeps long agent runs affordable.
Anyone running autonomous, multi-file coding loops who wants Opus-class output without Opus-class latency or cost.
Game devs and technical artists prototyping mechanics, scenes, and simulations.
Shipping MVPs and interactive demos where speed and budget both matter.
People bridging code and visuals — rendering, generative graphics, and hardware/CAD mockups.
It depends on the task. Grok 4.5 is positioned as “Opus-class,” and early users report it matches Opus-tier quality on coding and agentic work while running roughly twice as fast and costing noticeably less (community impressions, not official benchmarks). For long, autonomous build loops where speed and token cost add up, many builders now reach for Grok 4.5; for some reasoning- or writing-heavy tasks, others still prefer Claude or GPT models. On Happycapy you can switch models and compare on your own workload.
Grok 4.5 is xAI's newer iteration in the Grok 4 line, tuned for stronger agentic workflows with better speed and token efficiency. Builders describe it as noticeably faster and more cost-effective for multi-step coding and 3D build tasks than earlier Grok releases.
They are different but work together. Grok 4.5 is the model — the underlying intelligence. Grok Build is xAI's agentic build environment that many of the demos on this page use to turn a single prompt into a finished app, game, or 3D scene. On Happycapy, Grok 4.5 powers an equivalent agent loop inside a secure browser sandbox, so you get the same build-it-for-me workflow without extra setup.
Yes — that is a core use case. Given a goal, it can write a design document, break the work into phases, pull assets, and loop through implementation autonomously. Community builders have used Grok 4.5 to ship playable games, interactive apps, and full 3D scenes end-to-end, often in under an hour.
It is one of its standout strengths. Makers have used Grok 4.5 to build Unreal Engine 5 city scenes, physics-style simulations, Blender effects driven through MCP, browser 3D walkthroughs rendered with Gaussian Splatting, and CAD-style hardware enclosures — frequently from a single prompt in minutes.
Yes. Developers have run Grok 4.5 in Cursor (early access) and in xAI's Grok Build, and on Happycapy it runs as the engine behind an in-browser agent. It fits agentic, multi-file coding workflows across these environments.
Cost depends on where you run it, but builders consistently report Grok 4.5 costing a fraction of Opus for comparable work — one creator generated a full Unreal Engine scene for about $12 in API usage. On Happycapy, Grok 4.5 is a premium model on paid plans; you can create a free account to explore the platform first, then upgrade to run Grok 4.5.
Type your task into the prompt box on this page — the model is already set to Grok 4.5 — and hit send. Happycapy spins up a secure cloud sandbox and lets Grok 4.5 build, code, or render the task end-to-end, then delivers the result. No installs or API keys required.
Create a free account to explore Happycapy, then upgrade to put xAI’s fastest Opus-class model to work on real tasks — right in your browser, no setup needed.
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