GPT-5.3-Codex vs Grok-3
GPT-5.3-Codex (2026) and Grok-3 (2025) compare a coding-specialized model against a standalone API model. GPT-5.3-Codex ships a 400k-token context window, while Grok-3 ships a 131k-token context window. On pricing, Grok-3 costs $0.80/1M input tokens versus $1.75/1M for the alternative. This page treats the result as workflow and deployment fit, not a universal model winner.
Treat this as a product-type comparison: GPT-5.3-Codex is coding-specialized model, while Grok-3 is standalone API model. Choose based on workflow fit before reading any benchmark or price row as decisive.
Decision scorecard
Local evidence first| Signal | GPT-5.3-Codex | Grok-3 |
|---|---|---|
| Product type | Coding-specialized model | Standalone API model |
| Best for | custom coding agents, code generation, and tool loops | reasoning-heavy apps, multimodal apps, and tool-calling agents |
| Decision fit | Coding, RAG, and Agents | Coding, RAG, and Agents |
| Context window | 400k | 131k |
| Cheapest output | $14/1M tokens | $2.40/1M tokens |
| Provider routes | 3 tracked | 4 tracked |
| Shared benchmarks | 0 rows | 0 rows |
Decision tradeoffs
- GPT-5.3-Codex has the larger context window for long prompts, retrieval packs, or transcript analysis.
- GPT-5.3-Codex uniquely exposes Code execution and Computer use in local model data.
- Local decision data tags GPT-5.3-Codex for Coding, RAG, and Agents.
- Grok-3 has the lower cheapest tracked output price at $2.40/1M tokens.
- Grok-3 has broader tracked provider coverage for fallback and procurement flexibility.
- Grok-3 uniquely exposes Multimodal in local model data.
- Local decision data tags Grok-3 for Coding, RAG, and Agents.
Monthly cost at traffic
Estimate token spend from the cheapest tracked input and output route or tier on this page.
GPT-5.3-Codex
$4,900
Cheapest tracked route/tier: OpenRouter
Grok-3
$1,240
Cheapest tracked route/tier: Chutes AI
Estimated monthly gap: $3,660. Batch, cache, alternate speed tiers, and negotiated pricing are excluded from this local estimate.
Switch friction
- Provider overlap exists on OpenRouter; start route-level A/B tests there.
- Grok-3 is $11.60/1M tokens lower on cheapest tracked output pricing before cache, batch, or negotiated discounts.
- Check replacement coverage for Code execution and Computer use before moving production traffic.
- Grok-3 adds Multimodal in local capability data.
- Provider overlap exists on OpenRouter; start route-level A/B tests there.
- GPT-5.3-Codex is $11.60/1M tokens higher on cheapest tracked output pricing, so quality gains need to justify the spend.
- Check replacement coverage for Multimodal before moving production traffic.
- GPT-5.3-Codex adds Code execution and Computer use in local capability data.
Specs
| Specification | ||
|---|---|---|
| Released | 2026-02-05 | 2025-02-17 |
| Context window | 400k | 131k |
| Parameters | — | — |
| Architecture | decoder only | - |
| License | Proprietary | Proprietary |
| Openness | Proprietary | Proprietary |
| Commercial use | Commercial use with conditions | Commercial use with conditions |
| Knowledge cutoff | 2025-08 | 2025-04 |
Pricing and availability
| Pricing attribute | GPT-5.3-Codex | Grok-3 |
|---|---|---|
| Input price | $1.75/1M tokens | $0.80/1M tokens |
| Output price | $14/1M tokens | $2.40/1M tokens |
| Providers |
Capabilities
| Capability | GPT-5.3-Codex | Grok-3 |
|---|---|---|
| Vision | Yes | Yes |
| Multimodal | No | Yes |
| Reasoning | Yes | Yes |
| Function calling | Yes | Yes |
| Tool use | Yes | Yes |
| Structured outputs | Yes | Yes |
| Code execution | Yes | No |
| IDE integration | No | No |
| Computer use | Yes | No |
| Parallel agents | No | No |
Benchmarks
No shared benchmark rows are currently sourced for this pair.
Deep dive
The capability footprint differs most on multimodal input: Grok-3 and code execution: GPT-5.3-Codex. Both models share vision, reasoning mode, function calling, and tool use, 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 on the cheapest tracked provider, while Grok-3 lists $0.80/1M input and $2.40/1M 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 3 providers versus 4, so concentration risk also matters.
Choose GPT-5.3-Codex when coding workflow support and larger context windows are central to the workload. Choose Grok-3 when vision-heavy evaluation, 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.
FAQ
Which has a larger context window, GPT-5.3-Codex or Grok-3?
GPT-5.3-Codex supports 400k tokens, while Grok-3 supports 131k tokens. That gap matters most for long documents, large codebases, retrieval-heavy agents, and conversations where earlier context must remain visible. Use this as a quick comparison signal, then confirm the provider-specific limits before committing to production.
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 $0.80/1M input and $2.40/1M 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?
Both GPT-5.3-Codex and Grok-3 expose vision. 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 multimodal input, GPT-5.3-Codex or Grok-3?
Grok-3 has the clearer documented multimodal input signal in this comparison. If multimodal input 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, OpenAI API, and Vercel AI Gateway. Grok-3 is available on OpenRouter, xAI Console, Chutes AI, and Microsoft Foundry. Provider coverage can affect latency, region availability, compliance posture, and fallback options.
Continue comparing
Last reviewed: 2026-06-10. Data sourced from public model cards and provider documentation.