GLM 5.3 Flash vs Claude Opus 5: side-by-side summary

GLM 5.3 Flash and Claude Opus 5 are available through the OpenRouter API, so switching between them takes a model slug change rather than a new integration.

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.

Claude Opus 5, from Anthropic, has a 1,000,000-token context window and is priced at $5/M tokens input, $25/M tokens output on OpenRouter.

Context window

• GLM 5.3 Flash: 1,048,576 tokens
• Claude Opus 5: 1,000,000 tokens

Price

• GLM 5.3 Flash: $0.075/M tokens input, $0.25/M tokens output
• Claude Opus 5: $5/M tokens input, $25/M tokens output

Provided by

• GLM 5.3 Flash: Z.ai
• Claude Opus 5: Anthropic

• GLM 5.3 Flash model details, providers and pricing
• Claude Opus 5 model details, providers and pricing