GPT-5.3 Codex vs Grok 3

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. Strong enterprise-grade reasoning

• Built for deep logical reasoning, structured decision-making, and multi-step analysis.
• Performs exceptionally in domains requiring precision: law, finance, healthcare, and STEM.

2. Excellent at data extraction and summarization

• Optimized for structured extraction from documents, PDFs, tables, and complex text.
• Ideal for enterprise workflows like reporting, compliance automation, or knowledge mining.

3. High-performance coding capabilities

• Excels at code generation, debugging, refactoring, and explaining code.
• Competitive with top-tier coding models for multi-file, long-context code reasoning.

4. Supports function calling and structured outputs

• Integrates cleanly with agent frameworks and external tools.
• Predictable, schema-aligned responses suitable for production systems.

5. Large 131K context window

• Handles long documents, transcripts, contracts, codebases, or multi-document tasks.
• Useful for ingesting highly technical materials in one pass.

6. Efficient cost structure with cached token pricing

• Cached inputs: only $0.75 / 1M tokens, enabling large-scale systems.
• Encourages reuse for powerful retrieval-augmented workflows.

7. Enterprise reliability and availability

• Supported across multiple regions (us-east-1, eu-west-1).
• Consistent rate limits: 600 requests/min.
• Suitable for production-grade apps with stability requirements.

8. Supports advanced search capabilities

• Optional Live Search add-on for real-time knowledge retrieval.
• Pricing: $25 per 1K sources.