Build AI powered apps for your work

Get started free
LLM ComparisonGPT-5.1 CodexGPT-4 Turbo

GPT-5.1 Codex vs GPT-4 Turbo

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

Model Comparison

FeatureGPT-5.1 CodexGPT-4 Turbo
ProviderOpenAIOpenAI
Model Typetexttext
Context Window400,000 tokens128,000 tokens
Input Cost
$1.25/ 1M tokens
$10.00/ 1M tokens
Output Cost
$10.00/ 1M tokens
$30.00/ 1M tokens

Stop choosing. Use both.

With Appaca you don't have to pick — build apps that are powered by GPT-5.1 Codex, GPT-4 Turbo, for your specific use case.

Build your first app free

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.

GPT-4 Turbo

OpenAI

1. Strong reasoning for its generation

  • Next-gen version of GPT-4 designed to be cheaper and faster than the original.
  • Good for analytical tasks, structured writing, coding guidance, and multi-step reasoning.

2. Image input support

  • Accepts images and provides text-only outputs.
  • Useful for OCR, visual Q&A, document extraction, UI analysis, and design interpretation.

3. Stable performance

  • Predictable model behavior suitable for legacy systems still built on GPT-4.
  • Works reliably for established pipelines and enterprise workloads.

4. Large 128K context window

  • Handles long documents, multi-file inputs, or extended conversational sessions.
  • Allows complex prompt chaining and large instruction sets.

5. Broad endpoint compatibility

  • Works with Chat Completions, Responses API, Realtime API, Assistants, Batch, Fine-tuning, Embeddings, and more.
  • Supports streaming and function calling.

6. Good choice for cost-controlled GPT-4-class workloads

  • Although older, still useful for teams who want GPT-4-level reasoning without upgrading immediately.
  • A midpoint between legacy GPT-4 and modern GPT-4o/5.1 models.

7. Text-only output simplifies downstream use

  • Ensures deterministic outputs for applications that need reliable text generation.
  • Good for RAG, data pipelines, automation tools, and enterprise systems.

8. Recommended migration path

  • OpenAI now recommends using GPT-4o or GPT-5.1 for improved speed, cost, reasoning, and multimodal capability.
  • GPT-4 Turbo remains available for backward compatibility and stability.