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LLM ComparisonGPT-5.1 CodexGrok 4

GPT-5.1 Codex vs Grok 4

Compare GPT-5.1 Codex and Grok 4. Build AI products powered by either model on Appaca.

Model Comparison

FeatureGPT-5.1 CodexGrok 4
ProviderOpenAIxAI
Model Typetexttext
Context Window400,000 tokens256,000 tokens
Input Cost
$1.25/ 1M tokens
$3.00/ 1M tokens
Output Cost
$10.00/ 1M tokens
$15.00/ 1M tokens

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Strengths & Best Use Cases

GPT-5.1 Codex

OpenAI

1. Purpose-Built for Agentic Coding

  • Designed specifically for environments where the model acts as an autonomous or semi-autonomous coding agent.
  • Optimized for multi-step reasoning in code tasks such as planning, refactoring, debugging, file generation, and tool coordination.

2. Enhanced Coding Intelligence

  • Extends GPT-5.1's advanced reasoning capabilities to handle complex software architecture decisions.
  • Better accuracy in code generation across languages (JavaScript, Python, TypeScript, Go, Rust, etc.).
  • Produces cleaner, more idiomatic code aligned with modern frameworks and best practices.

3. Superior Tool Use & Code Navigation

  • Excels at reading, understanding, and transforming multi-file codebases.
  • Works well with Codex workflows that simulate real developer tooling.
  • Strong at following function signatures, constraints, and code patterns within an existing project.

4. Long-Range Context Awareness

  • 400,000-token context window enables the model to ingest large repositories or multiple files simultaneously.
  • Supports deep analysis of project structures, dependencies, and cross-file logic.

5. Multi-Modal Development Capabilities

  • Accepts text + image input and output - suitable for tasks like:
    • Reading UI mockups or screenshots to generate code
    • Understanding architectural diagrams
    • Reviewing images of whiteboard sessions

6. Agentic Workflow Optimization

  • Built to manage longer chains of thought and execution typically required in:
    • Automated code repair
    • Project bootstrapping
    • Linting and migration tasks
    • Long-running coding agents using planning + execution loops

7. Continually Updated Model Snapshot

  • Codex-specific version receives regular upgrades behind the scenes.
  • Ensures the latest coding improvements without requiring developers to update model names.

8. Reliable Instruction Following

  • Highly consistent in honoring explicit constraints:
    • Code styles
    • Folder structures
    • API contracts
    • Framework conventions

9. Broad API Support

  • Works across Chat Completions, Responses API, Realtime, Assistants, and more.
  • Ideal for apps that need live, reasoning-heavy coding agents or generative dev environments.

Grok 4

xAI

1. Flagship-level reasoning and math performance

  • Designed for world-class reasoning depth, precision, and multi-step logical chains.
  • Excels at STEM, mathematics, symbolic operations, proofs, and analytical workloads.

2. Powerful multimodal understanding

  • Supports text, images, and other modalities.
  • Handles cross-modal reasoning tasks requiring context synthesis.

3. Extreme capability across diverse tasks

  • Positioned as a top-tier 'jack of all trades' model.
  • Strong in natural language, coding, knowledge retrieval, and structured generation.

4. Large 256K context window

  • Enables analysis of long documents, entire codebases, multi-document packs, and extensive agent sessions.
  • Supports workloads that require persistent reasoning across large inputs.

5. Advanced developer tooling support

  • Function calling for tool-augmented workflows.
  • Structured outputs for predictable, schema-controlled generation.
  • Integrates smoothly with agents and complex automation pipelines.

6. Efficient caching for cost reduction

  • Cached input tokens discounted to $0.75 / 1M tokens.
  • Encourages RAG, retrieval pipelines, and multi-step conversational workflows.

7. Production-ready performance

  • Stable rate limits: 480 requests per minute.
  • High token throughput: 2,000,000 tokens per minute.
  • Available across multiple xAI regional clusters.

8. Optional Live Search augmentation

  • Add-on: $25 per 1K sources.
  • Enhances factual accuracy and real-time information retrieval.