GPT-5.1-Codex vs multi-qa-mpnet-base-dot-v1: side-by-side summary

GPT-5.1-Codex and multi-qa-mpnet-base-dot-v1 are available through the OpenRouter API, so switching between them takes a model slug change rather than a new integration.

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.

multi-qa-mpnet-base-dot-v1, from sentence-transformers, has a 512-token context window and is priced at $0.005/M tokens on OpenRouter.

Context window

• GPT-5.1-Codex: 400,000 tokens
• multi-qa-mpnet-base-dot-v1: 512 tokens

Price

• GPT-5.1-Codex: $1.25/M tokens input, $10/M tokens output
• multi-qa-mpnet-base-dot-v1: $0.005/M tokens

Provided by

• GPT-5.1-Codex: OpenAI
• multi-qa-mpnet-base-dot-v1: sentence-transformers

• GPT-5.1-Codex model details, providers and pricing
• multi-qa-mpnet-base-dot-v1 model details, providers and pricing