GPT-5.3-Codex vs Grok-3
GPT-5.3-Codex (2026) and Grok-3 (2026) are agentic coding models from OpenAI and xAI. GPT-5.3-Codex ships a not-yet-sourced context window, while Grok-3 ships a 1M-token context window. On pricing, Grok-3 costs $0.8/1M input tokens versus $1.75/1M for the alternative. This comparison covers specs, pricing, capabilities, benchmarks, provider availability, and production fit. It focuses on practical selection signals rather than broad model-family marketing.
Grok-3 is ~119% cheaper at $0.8/1M; pay for GPT-5.3-Codex only for coding workflow support.
Specs
| Released | 2026-02-05 | 2026-01-15 |
| Context window | — | 1M |
| Parameters | — | 1B |
| Architecture | decoder only | - |
| License | Proprietary | Proprietary |
| Knowledge cutoff | - | 2025-04 |
Pricing and availability
| GPT-5.3-Codex | Grok-3 | |
|---|---|---|
| Input price | $1.75/1M tokens | $0.8/1M tokens |
| Output price | $14/1M tokens | $2.4/1M tokens |
| Providers |
Capabilities
| GPT-5.3-Codex | Grok-3 | |
|---|---|---|
| Vision | ||
| Multimodal | ||
| Reasoning | ||
| Function calling | ||
| Tool use | ||
| Structured outputs | ||
| Code execution |
Benchmarks
No shared benchmark rows are currently sourced for this pair.
Deep dive
The capability footprint differs most on vision: Grok-3, reasoning mode: Grok-3, and code execution: GPT-5.3-Codex. Both models share multimodal input, function calling, tool use, and structured outputs, so the practical split is not just feature count. Use those differences to decide whether the page is about raw model quality, agentic coding support, multimodal ingestion, or predictable structured API behavior.
For cost, GPT-5.3-Codex lists $1.75/1M input and $14/1M output tokens, while Grok-3 lists $0.8/1M input and $2.4/1M output tokens on the cheapest tracked provider. A 70/30 input-output blend puts Grok-3 lower by about $4.14 per million blended tokens. Availability is 1 providers versus 3, so concentration risk also matters.
Choose GPT-5.3-Codex when coding workflow support are central to the workload. Choose Grok-3 when reasoning depth, lower input-token cost, and broader provider choice are more important. For production, rerun your own prompts through the exact provider, region, and tool stack you plan to ship. This keeps the decision grounded in measurable tradeoffs instead of brand-level assumptions. It also helps separate model capability from provider packaging, which can change cost and latency. For teams standardizing a stack, that distinction is often the difference between a benchmark win and a reliable deployment.
FAQ
Which is cheaper, GPT-5.3-Codex or Grok-3?
Grok-3 is cheaper on tracked token pricing. GPT-5.3-Codex costs $1.75/1M input and $14/1M output tokens. Grok-3 costs $0.8/1M input and $2.4/1M output tokens. Provider discounts or batch pricing can still change the final bill.
Is GPT-5.3-Codex or Grok-3 open source?
GPT-5.3-Codex is listed under Proprietary. Grok-3 is listed under Proprietary. License labels affect whether you can self-host, redistribute weights, or rely only on hosted APIs, so confirm the upstream license before deployment.
Which is better for vision, GPT-5.3-Codex or Grok-3?
Grok-3 has the clearer documented vision signal in this comparison. If vision is mission-critical, validate it against the provider endpoint because model-level support and API-level exposure can differ. Use this as a quick comparison signal, then confirm the provider-specific limits before committing to production.
Which is better for multimodal input, GPT-5.3-Codex or Grok-3?
Both GPT-5.3-Codex and Grok-3 expose multimodal input. The better choice depends on benchmark fit, context budget, pricing, and whether your provider route exposes the same capability surface. Use this as a quick comparison signal, then confirm the provider-specific limits before committing to production.
Which is better for reasoning mode, GPT-5.3-Codex or Grok-3?
Grok-3 has the clearer documented reasoning mode signal in this comparison. If reasoning mode is mission-critical, validate it against the provider endpoint because model-level support and API-level exposure can differ.
Where can I run GPT-5.3-Codex and Grok-3?
GPT-5.3-Codex is available on OpenRouter. Grok-3 is available on OpenRouter, xAI Console, and Chutes AI. Provider coverage can affect latency, region availability, compliance posture, and fallback options. Use this as a quick comparison signal, then confirm the provider-specific limits before committing to production.
Continue comparing
Last reviewed: 2026-04-24. Data sourced from public model cards and provider documentation.