Kimi K3 vs GPT-5.3-Codex-Spark
Moonshot AI Kimi K3 | OpenAI GPT-5.3-Codex-Spark | |
|---|---|---|
| Overview | ||
| Company | Moonshot AI | OpenAI |
| Release date | Jul 16 2026 | Feb 12 2026 |
| Access | Open Weight | Proprietary |
| Specifications | ||
Parameters | 2.8T | — |
Context window | 1M | 128k |
| Benchmarks | ||
Agentic coding DeepSWE 1.0Artificial Analysis' independent test of deep, agentic software-engineering work — the AI has to plan and carry out substantial coding tasks end to end. Higher is better. | 67.5% | — |
Agentic terminal coding Terminal-Bench 2.1Can the AI work in a command-line terminal — running commands and finishing technical setup tasks the way a developer would? Higher is better. | 88.3% | — |
Multi-step tool use MCP AtlasCan the AI chain together many tools and steps to complete one bigger task, rather than doing just a single thing? Higher is better. | 84.2% | — |
Professional tool use JobBenchTests the AI on professional workplace tasks that require using real work tools — the kind of multi-step jobs an office worker handles. Higher is better. | 52.9% | — |
Personal tool use Toolathlon-VerifiedTests how well the AI uses everyday personal tools and apps to get things done — a human-checked version of Toolathlon. Higher is better. | 73.2% | — |
Web browsing BrowseCompCan the AI browse the web and track down hard-to-find answers? Higher is better. | 91.2% | — |
Multidisciplinary reasoning Humanity's Last Exam · no toolsHumanity's Last Exam — extremely hard expert questions across many subjects, written so you can't just look up the answer. “No tools” means the AI answers on its own. Higher is better. | 43.5% | — |
Multidisciplinary reasoning Humanity's Last Exam · with toolsHumanity's Last Exam — extremely hard expert questions across many subjects. “With tools” means the AI is allowed to search the web or run code while answering. Higher is better. | 56% | — |
Science GPQA DiamondGraduate-level science questions in biology, physics, and chemistry — hard enough that subject-matter PhDs score around 65%. Higher is better. | 93.5% | — |
Knowledge work GDPval-AA v2economically valuable knowledge work (v2, re-based Elo) | 1668 | — |
Chart reasoning CharXiv ReasoningCan the AI read and reason about complex charts and figures, not just text? Higher is better. | 84.8% | — |
Multimodal reasoning MMMU-ProA tougher version of MMMU — college-level questions that mix images, diagrams, and text together. Higher is better. | 81.6% | — |
| Timeline | ||
| Release gap | GPT-5.3-Codex-Spark shipped 154 days before Kimi K3 | |
Which is better: Kimi K3 or GPT-5.3-Codex-Spark?
Kimi K3 and GPT-5.3-Codex-Spark don't publish scores on any of the same benchmarks, so there's no direct head-to-head comparison. GPT-5.3-Codex-Spark shipped 154 days before Kimi K3, so benchmark comparisons should account for the intervening progress.
Context windows are 1M (Kimi K3) vs 128k (GPT-5.3-Codex-Spark). Kimi K3 is open weight, while GPT-5.3-Codex-Spark is proprietary.
Direct benchmark comparisons are unavailable — Kimi K3 and GPT-5.3-Codex-Spark don't publish scores on any of the same benchmarks.
Frequently asked questions
Kimi K3 was released by Moonshot AI on Jul 16 2026.
GPT-5.3-Codex-Spark was released by OpenAI on Feb 12 2026.
Kimi K3 has a 1M context window; GPT-5.3-Codex-Spark has 128k.
Kimi K3 is an open weight model released by Moonshot AI. GPT-5.3-Codex-Spark is a proprietary model released by OpenAI.