GLM 5.3 Flash vs Claude Opus 5: price, context window and capabilities
GLM 5.3 Flash (z-ai/glm-5.3-flash) from Z.ai and Claude Opus 5 (anthropic/claude-opus-5) from Anthropic are both multimodal language models on the OceanToken API. GLM 5.3 Flash costs less per token than Claude Opus 5: $0.15 against $4.50 per 1M input tokens (97% less) and $0.50 against $22.50 per 1M output tokens (98% less). Claude Opus 5 is 10% off its official price on OceanToken, for every account. GLM 5.3 Flash has the larger context window: 1.05M tokens (1,048,576) against 1M (1,000,000) for Claude Opus 5. Both support tool calling, reasoning, structured outputs and image input; only GLM 5.3 Flash also lists video input; only Claude Opus 5 also lists file input.
Side by side
| Spec | GLM 5.3 Flash | Claude Opus 5 −10% |
|---|---|---|
| Model | GLM 5.3 Flashz- | Claude Opus 5anthropic/ |
| Publisher | Z.ai | Anthropic |
| Kind | Text, vision & video | Text & vision |
| Context window | 1.05M tokens1,048,576 | 1M tokens1,000,000 |
| Input price | $0.15 / 1M tokens | $4.50 / 1M tokens |
| Output price | $0.50 / 1M tokens | $22.50 / 1M tokens |
| Cached input price | $0.03 / 1M tokens | $0.50 / 1M tokens |
| Cache write price | – | $6.25 / 1M tokens |
| Web search price | – | $0.01 / search |
| Discount (vs official, top tier) | — | −10% |
| Inputs | text, images and video | text, images and files |
| Outputs | text | text |
| Tool calling | Yes | Yes |
| Reasoning | Yes | Yes |
| Structured outputs | Yes | Yes |
About these prices
Which should you choose?
- Choose GLM 5.3 Flash to spend less per token: 97% less for input and 98% less for output than Claude Opus 5.
- Choose GLM 5.3 Flash for the longest inputs: its context window holds 1.05M tokens against 1M for Claude Opus 5.
- Choose GLM 5.3 Flash if you need video input: Claude Opus 5 does not list it.
- Not sure? Call both with the same OceanToken API key and compare them on your own prompts; each request is billed per use from one prepaid balance.
Get API Key GLM 5.3 Flash Claude Opus 5
Frequently asked questions
Which is cheaper, GLM 5.3 Flash or Claude Opus 5?
GLM 5.3 Flash. GLM 5.3 Flash costs less per token than Claude Opus 5: $0.15 against $4.50 per 1M input tokens (97% less) and $0.50 against $22.50 per 1M output tokens (98% less). Claude Opus 5 is 10% off its official price on OceanToken, for every account. The OceanToken console always shows the current price.
Which has the larger context window, GLM 5.3 Flash or Claude Opus 5?
GLM 5.3 Flash. GLM 5.3 Flash has the larger context window: 1.05M tokens (1,048,576) against 1M (1,000,000) for Claude Opus 5.
Can I call both GLM 5.3 Flash and Claude Opus 5 with one API key?
Yes. Both are on the OceanToken API at https://api.oceantoken.ai/v1: one API key and one prepaid balance call either model. Send the model id z-ai/glm-5.3-flash or anthropic/claude-opus-5.
Models and publishers
GLM 5.3 Flash · Claude Opus 5 · All Z.ai models · All Anthropic models
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