GPT-5.3 Codex
gpt-5.3-codexGPT-5.3-Codexgpt-53-codexopenai-gpt-53-codex- 🔧 OpenAI's Codex-native coding agent built on GPT-5.3.
- 🆕 Unifies GPT-5.2-Codex coding with GPT-5.2 reasoning in one model.
- ⚡ OpenAI reports it runs 25% faster than its predecessor.
- 📏 Catalog lists a 400,000-token context window.
- 👁️ Supports vision, function calling, and web search.
- 🎯 Tunable reasoning effort: low, medium, high, xhigh.
- 🧠 Targets long-horizon debugging, deployment, and software-lifecycle work.
- 💬 Delivered through OpenAI's Responses API for agentic coding.
OpenAI is an American artificial intelligence research organization headquartered in San Francisco, structured as both a for-profit public benefit corporation and a nonprofit foundation. The lab developed the GPT family of large language models, the DALL-E image generation…
Explore 27 more models by OpenAI →GPT-5.3 Codex is OpenAI's specialized coding model, described as a Codex-native agent that pairs frontier coding performance with general reasoning to support long-horizon, real-world technical work. It is the third major iteration of the Codex-specific line and the first to combine the Codex coding training stack with GPT-5.3's reasoning and general-intelligence base in a single unified model. Beyond writing and reviewing code, OpenAI positions it for the broader software lifecycle—debugging, deploying, monitoring, and writing product docs, tests, and metrics.
Compared with its same-family predecessor GPT-5.2 Codex, OpenAI states the new model advances both the frontier coding ability of GPT-5.2-Codex and the reasoning and professional-knowledge capabilities of GPT-5.2, together in one model that is also 25% faster. According to OpenAI, it sets new highs on SWE-Bench Pro and Terminal-Bench among the four benchmarks the company uses to measure coding, agentic, and real-world capability.
The model exposes selectable reasoning effort (low, medium, high, and xhigh) and is delivered through OpenAI's Responses API. A separate, smaller research-preview variant, Codex-Spark, targets near-instant iteration with a 128K context window and text-only input.
Within OpenAI's wider 2026 lineup, GPT-5.3 Codex sits alongside newer general-purpose releases such as GPT-5.4 and the later GPT-5.5.
This About section is AI-generated from public sources via VeniceStats + Venice inference, with no human editing. It may contain inaccuracies.
| Seller | Reputation↓ | Routing | Input $/M | Cached $/M | Output $/M | Categories | API |
|---|---|---|---|---|---|---|---|
| ▲ Apex Ant 0x73b4…e736 | 91.03 | #2 | $1.095 | $0.11 | $8.75 | chat,coding,tasks,vision,multimodal,reasoning,long-context,agents | openai-chat-completions |
| NovaRoute AI 0xc50d…ed7b | 67.67 | #1 | $1.0841 | $1.0841 | $8.6625 | chat,coding,code,reasoning,tasks,developer,codex,gpt,surplus,openai-compatible,low-cost,verified,github,response-auth,base-usdc,monitored | openai-chat-completions |
| Fire Ant 🔥🐜 0xbe05…bc5d | 40.37 | gated | $1.859 | $0.1859 | $14.8549 | — | — |
| StrataCode 0x6f9b…befe | 25.00 | gated | $2.00 | $2.00 | $14.25 | chat,coding,json,reasoning,tools | openai-chat-completions |
| Meridian AI 0x8c8c…06f5 | 5.64 | gated | $0.2129 | $0.2129 | $1.701 | chat,coding | openai-chat-completions |
| Apex TEE Test 0xe672…7955 | 0.51 | gated | $0.5913 | $0.0624 | $4.725 | chat,coding,tasks,vision,multimodal,reasoning,long-context,agents | openai-chat-completions |
| AntFeed 0xddb6…1442 | 0.00 | gated | $1.925 | $1.925 | $14.1167 | chat,coding,reasoning,long-context | openai-chat-completions |
| antseed-neon-puma-944e 0x6650…944e | 0.00 | gated | $0.7468 | $0.219 | $5.9675 | chat,coding,math | openai-chat-completions |
| Leftermute 0x388b…5389 | 0.00 | gated | $0.1991 | $0.1991 | $1.5908 | chat,coding,json,math,tools | openai-chat-completions |
| stupmonke 0x789c…5f1b | 0.00 | gated | $0.0083 | $0.0008 | $0.10 | chat,coding,reasoning | openai-chat-completions |
"Best price" and the seller table are live AntSeed catalog data (advertised $/1M tokens — or $ per generated image for unit-billed image models — not settled amounts). Reputation = on-chain trust (0-100). "Routing" = the SDK's default buyer routing (what the VPR desktop app ships with): a trust ≥ 60 gate on the effective reputation, then cheapest-first among routable sellers; live failover state (per-peer cooldowns) is buyer-side runtime and not included. Model knowledge (TLDR, provider, About) via the VeniceStats enrichment layer. Advertised catalog, not the model used in any specific purchase. "Usage on AntSeed" counts only settlements whose buyers share the per-model split on-chain (metadata v2/v3, opt-in), so every usage figure is a lower bound.