GPT-5.2 Codex

Overview

GPT-5.2 Codex is OpenAI's coding-specialized model, released January 14, 2026 — five weeks after the base GPT-5.2. It builds on GPT-5.2's strong reasoning and professional-grade performance and fine-tunes it specifically for software engineering tasks: writing, reviewing, debugging, and reasoning about code across a wide range of languages and frameworks. Codex represents OpenAI's direct answer to Anthropic's Claude Sonnet and Opus models, which have led SWE-bench Verified rankings through much of 2025.

For developers building coding agents, CI/CD automation, or AI-assisted software tools, GPT-5.2 Codex is OpenAI's recommended model — combining GPT-5.2's deep reasoning with optimizations for code-specific tasks including function calling, tool use, and structured output generation.

Specifications

• Developer: OpenAI
• Model String: gpt-5.2-codex-2026-01-14
• Release Date: January 14, 2026
• Type: Large Language Model (LLM), code-optimized
• Context Window: 400,000 tokens
• Max Output: 128,000 tokens
• Access: OpenAI API, ChatGPT (Plus/Team/Enterprise), Azure OpenAI Service
• Pricing: Aligned with GPT-5.2 base pricing (check OpenAI docs for current rate; ~$1.75–$14.00 per million tokens)

Capabilities

Software Engineering: Purpose-built for real-world coding tasks — not just code completion but architectural reasoning, debugging multi-file issues, writing tests, and explaining complex codebases. Competitive with Anthropic Claude on SWE-bench Verified at launch.

Long-Context Code Understanding: With a 400K token context window, GPT-5.2 Codex can hold entire large codebases in context simultaneously — enabling analysis across many files without chunking or summarization workarounds.

Tool Use & Function Calling: Strong support for structured outputs, function calling, and tool integrations — essential for coding agents that need to interact with APIs, databases, and external services.

Debugging & Code Review: Excels at identifying bugs, security vulnerabilities, and performance issues across large codebases; can explain reasoning behind suggestions clearly.

Limitations

Like all specialized variants, GPT-5.2 Codex is optimized for coding at some cost to general-purpose performance. For tasks spanning both professional knowledge work and coding — research-heavy software projects, technical writing, architecture docs — the base GPT-5.2 may be a better fit. The Pro pricing tier ($21/$168 per million tokens) makes high-volume coding pipelines expensive compared to Anthropic's Claude Sonnet 4.6 at $3/$15.

Recent Developments

• January 14, 2026 Launch: Released as OpenAI's dedicated coding model, completing the GPT-5.2 family alongside the Instant, Thinking, and Pro variants of the base model.
• Competitive Positioning: Entered a market where Anthropic's Claude models had held the SWE-bench Verified leaderboard for most of 2025. OpenAI has not published a single headline SWE-bench number for Codex, instead positioning it on GDPval coding occupations and real-world developer preference.

Last Updated

February 26, 2026