Direct answer
Z.ai’s developer documentation identifies a model called GLM-5.3-Flash and gives its API model code as glm-5.3-flash. The available documentation does not establish that “GLM-5 Flash” is an official name or alias for it. The API and pricing details below apply to GLM-5.3-Flash through Z.ai, not to an unconfirmed model name or to other providers.
Z.ai documents GLM-5.3-Flash for its chat-completions API. The documented endpoint is https://api.z.ai/api/paas/v4/chat/completions; the API uses Bearer authentication. This confirms documented Z.ai API access, not availability through TokenForge or another provider.
Who should consider GLM-5.3-Flash?
Consider GLM-5.3-Flash if your application needs text, image, video, or file input, or could benefit from a long context window. Z.ai lists a 1M-token context window, 128K maximum output, and text output. These specifications establish supported modalities and limits; they do not establish accuracy or performance on a particular workload.
The available official-document excerpts do not verify coding or tool-use performance, benchmark results, or a latency target for this model. If those are important to your decision, test the exact API model ID on representative prompts before committing to production.
Z.ai API access and pricing
Z.ai’s listed prices are in USD per 1 million tokens:
| Model | Input | Cached input | Output |
|---|---|---|---|
| GLM-5.3-Flash | $0.15 | $0.03 | $0.50 |
At the listed uncached rates, 1 million input tokens plus 1 million output tokens would cost $0.65, before any other applicable charges. Check Z.ai’s current pricing and the terms applicable to your account before budgeting.
To make a chat-completions request, use a Z.ai API key as a Bearer token and set model to glm-5.3-flash:
curl -X POST 'https://api.z.ai/api/paas/v4/chat/completions' \
-H 'Authorization: Bearer YOUR_API_KEY' \
-H 'Content-Type: application/json' \
-d '{
"model": "glm-5.3-flash",
"messages": [
{"role": "user", "content": "Summarize the key points in this text."}
],
"stream": false
}'
The cited API reference describes response fields including choices and usage. The documentation excerpts available here list image, video, and file input, but do not establish their request formats or detailed limits; check the applicable API reference before implementing those input paths.
Practical selection check
Before production use, evaluate the documented model ID on representative tasks. Track task success, errors, response time, and token use; include visual or long-context examples if those capabilities matter to your application. This is a suggested evaluation approach, not a test result.
Bottom line: Z.ai documents GLM-5.3-Flash as an API model with multimodal input, a 1M-token context window, 128K maximum output, and published token rates. The evidence available here does not confirm that the shorter query “GLM-5 Flash” is an official alias. No TokenForge-specific availability is established.
Sources
GLM-5.3-Flash/FlashX — Z.ai Developer Documentation
Pricing — Z.ai Developer Documentation