DeepSeek V3.1 Terminus vs GPT-5.1-Codex: side-by-side summary

DeepSeek V3.1 Terminus and GPT-5.1-Codex are available through the OpenRouter API, so switching between them takes a model slug change rather than a new integration.

DeepSeek V3.1 Terminus, from DeepSeek, has a 163,840-token context window and is priced at $0.27/M tokens input, $1/M tokens output on OpenRouter.

GPT-5.1-Codex, from OpenAI, has a 400,000-token context window and is priced at $1.25/M tokens input, $10/M tokens output on OpenRouter.

Context window

• DeepSeek V3.1 Terminus: 163,840 tokens
• GPT-5.1-Codex: 400,000 tokens

Price

• DeepSeek V3.1 Terminus: $0.27/M tokens input, $1/M tokens output
• GPT-5.1-Codex: $1.25/M tokens input, $10/M tokens output

Provided by

• DeepSeek V3.1 Terminus: DeepSeek
• GPT-5.1-Codex: OpenAI

• DeepSeek V3.1 Terminus model details, providers and pricing
• GPT-5.1-Codex model details, providers and pricing