GPT-5.3 Codex vs Mistral Small 3.1 24B Instruct

GPT-5.3 Codex

OpenAI

GPT-5.3 Codex, released by OpenAI in February 2026, is a coding-specialized large language model from the GPT-5.3 family. It targets software engineering workflows including automated code generation, test writing, and agentic multi-file editing, built on the incremental improvements of the GPT-5.3 generation.

Mistral Small 3.1 24B Instruct

Mistral AI

Mistral Small 3.1 is a 24-billion-parameter multimodal model from Mistral AI, released in March 2025 as an update to Mistral Small 3 that added vision understanding and expanded the context window from 32K to 128K tokens. The model accepts both text and image inputs, broadening its applicability to document analysis, image-grounded reasoning, and mixed-media workflows without requiring an increase in parameter count. Released under Apache 2.0, it continued Mistral's pattern of incremental capability gains delivered in compact, practically deployable open-weight packages.