GPT-5.3 Codex vs Grok 3 Mini

1. Strongest Codex Model for Agentic Engineering

• OpenAI positions GPT-5.3 Codex as its most capable agentic coding model to date.
• Built for long-horizon software engineering tasks that require planning, iteration, and reliable code transformation across files.

2. Configurable Reasoning + Multimodal Input

• Supports configurable reasoning effort from low to xhigh so teams can trade off depth against latency.
• Accepts both text and image inputs while producing text output.

3. Large Context for Real Codebases

• 400 k token context window helps it work across larger repositories, implementation plans, and supporting documentation.
• Allows up to 128 k output tokens for longer code generations, patches, and technical write-ups.

4. Current Knowledge for Modern Dev Workflows

• Knowledge cut-off of Aug 31 2025 keeps it aligned with newer frameworks, libraries, and tooling.
• Supports streaming, function calling, and structured outputs for agent-style coding workflows.

1. Lightweight but thoughtful reasoning

• Designed to 'think before responding' with accessible raw thought traces.
• Excellent for logic puzzles, lightweight reasoning, and systematic tasks.

2. Extremely cost-efficient

• Only $0.30 per 1M input tokens and $0.50 per 1M output tokens.
• Cached token support lowers cost to $0.075 per 1M tokens.

3. Fast and responsive

• Optimized for low-latency applications and high-throughput use cases.
• Suitable for chatbots, assistants, and automation flows.

4. Supports modern developer features

• Function calling for tool-augmented workflows.
• Structured outputs for schema-controlled responses.
• Integrates cleanly with agents and pipelines.

5. Large 131K context window

• Can understand and work with long documents, transcripts, or multi-turn sessions.

6. Great for non-domain-heavy tasks

• Useful for summarization, rewriting, extraction, everyday reasoning, and app logic.
• Does not require domain expertise to operate effectively.

7. Compatible with enterprise infrastructure

• Stable rate limits: 480 requests per minute.
• Same API structure as all Grok 3 models.

8. Optional Live Search support

• $25 per 1K sources for real-time search augmentation.