Comprehensive side-by-side LLM comparison
. Both models have their strengths depending on your specific coding needs.
DeepSeek
DeepSeek-V3.1, released by DeepSeek in August 2025, is a hybrid large language model with 671 billion total parameters (37 billion active) that unifies the capabilities of DeepSeek-V3 and DeepSeek-R1 in a single model. It features a 128K token context window and supports both direct generation and extended reasoning modes selectable via the chat template. DeepSeek-V3.1 targets general-purpose tasks, coding, and complex reasoning under an open MIT license.
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.
5 months newer

DeepSeek-V3.1
DeepSeek
2025-08-21

GPT-5.3 Codex
OpenAI
2026-02
Context window and performance specifications
Available providers and their performance metrics
DeepSeek-V3.1
DeepSeek
GPT-5.3 Codex
DeepSeek-V3.1
GPT-5.3 Codex
DeepSeek-V3.1
GPT-5.3 Codex