GLM 5.3 Flash vs Claude Sonnet 5: price, context window and capabilities
GLM 5.3 Flash (z-ai/glm-5.3-flash) from Z.ai and Claude Sonnet 5 (anthropic/claude-sonnet-5) from Anthropic are both multimodal language models on the OceanToken API. GLM 5.3 Flash costs less per token than Claude Sonnet 5: $0.15 against $1.80 per 1M input tokens (92% less) and $0.50 against $9.00 per 1M output tokens (94% less). Claude Sonnet 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 Sonnet 5. Both support tool calling, reasoning, structured outputs and image input; only GLM 5.3 Flash also lists video input; only Claude Sonnet 5 also lists file input.
Side by side
| Spec | GLM 5.3 Flash | Claude Sonnet 5 −10% |
|---|---|---|
| Model | GLM 5.3 Flashz- | Claude Sonnet 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 | $1.80 / 1M tokens |
| Output price | $0.50 / 1M tokens | $9.00 / 1M tokens |
| Cached input price | $0.03 / 1M tokens | $0.20 / 1M tokens |
| Cache write price | – | $2.50 / 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: 92% less for input and 94% less for output than Claude Sonnet 5.
- Choose GLM 5.3 Flash for the longest inputs: its context window holds 1.05M tokens against 1M for Claude Sonnet 5.
- Choose GLM 5.3 Flash if you need video input: Claude Sonnet 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 Sonnet 5
Frequently asked questions
Which is cheaper, GLM 5.3 Flash or Claude Sonnet 5?
GLM 5.3 Flash. GLM 5.3 Flash costs less per token than Claude Sonnet 5: $0.15 against $1.80 per 1M input tokens (92% less) and $0.50 against $9.00 per 1M output tokens (94% less). Claude Sonnet 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 Sonnet 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 Sonnet 5.
Can I call both GLM 5.3 Flash and Claude Sonnet 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-sonnet-5.
Models and publishers
GLM 5.3 Flash · Claude Sonnet 5 · All Z.ai models · All Anthropic models
More comparisons
GLM 5.3 Flash vs Claude Sonnet 5.5 · GLM 5.3 Flash vs Claude Opus 5.5 · GLM 5.3 Flash vs Claude Fable 5.1 · GLM 5.3 Flash vs Claude Opus 5 · All comparisons