GPT-5.6 Luna vs GLM 5.3 Flash: side-by-side summary

GPT-5.6 Luna and GLM 5.3 Flash are available through the OpenRouter API, so switching between them takes a model slug change rather than a new integration.

GPT-5.6 Luna, from OpenAI, has a 1,050,000-token context window and is priced at $0.20/M tokens input, $1.20/M tokens output on OpenRouter.

GLM 5.3 Flash, from Z.ai, has a 1,048,576-token context window and is priced at $0.075/M tokens input, $0.25/M tokens output on OpenRouter.

Context window

• GPT-5.6 Luna: 1,050,000 tokens
• GLM 5.3 Flash: 1,048,576 tokens

Price

• GPT-5.6 Luna: $0.20/M tokens input, $1.20/M tokens output
• GLM 5.3 Flash: $0.075/M tokens input, $0.25/M tokens output

Provided by

• GPT-5.6 Luna: OpenAI
• GLM 5.3 Flash: Z.ai

• GPT-5.6 Luna model details, providers and pricing
• GLM 5.3 Flash model details, providers and pricing