Z.ai and BigModel both belong to the Zhipu (Z.AI) family, but they serve different regions and should be treated as relatively independent platforms. Z.ai primarily serves international users; BigModel (bigmodel.cn / open.bigmodel.cn) primarily serves individuals, companies, and developers in mainland China. Both can provide GLM models, APIs, and Coding Plans, but accounts, balances, plan quotas, and API keys should not be assumed to transfer between them.
What Is Zhipu AI?
Zhipu (Z.AI) was founded in 2019 from technology developed at Tsinghua University's Knowledge Engineering Group (KEG). It is not a single chatbot: the company develops foundation models, web assistants, agents, and a MaaS platform for general users, developers, and enterprise teams.
Zhipu's corporate site lists Z.ai in its product portfolio and BigModel as its MaaS platform. They share the GLM technology and brand family, while differing in service entry points, operating entities, billing, data-processing regions, and account management.
Z.ai vs BigModel
| Item | Z.ai | BigModel |
|---|---|---|
| Primary role | Zhipu's global platform | Zhipu's mainland China MaaS platform |
| Audience | International individuals, developers, and companies | Individuals, developers, and companies in mainland China |
| Main services | AI chat, agents, APIs, and GLM Coding Plan | APIs, deployment and fine-tuning, evaluations, knowledge bases, and GLM Coding Plan |
| Primary billing currency | USD | RMB |
| General API endpoint | https://api.z.ai/api/paas/v4 | https://open.bigmodel.cn/api/paas/v4 |
| Coding Plan endpoint | https://api.z.ai/api/coding/paas/v4 | https://open.bigmodel.cn/api/coding/paas/v4 |
| Operator and data processing | Its privacy policy names Singapore-based JINGSHENG HENGXING TECHNOLOGY PTE. LTD. as controller and says personal data is generally processed in Singapore | Its privacy policy names Beijing Zhipu Huazhang Technology Co., Ltd. as operator and data processor |
| Account requirements | Governed by its international account and regional rules | Identity verification may be required for features such as API keys |
The API addresses above are the general OpenAI-compatible endpoints. Coding Plans also provide Anthropic-compatible endpoints. Select the endpoint for both the correct platform and the correct plan type: general balance endpoints and Coding Plan endpoints are not interchangeable.
Do They Offer the Same Models?
Their core models come from the same GLM family. Current Zhipu documentation lists models such as GLM-5.3 and GLM-5.3-Flash in both BigModel and Z.ai connection flows, although actual availability depends on the platform, account permissions, and plan.
Shared model lineage does not make the hosted services identical. Model rollout timing, pricing and promotions, concurrency limits, quotas, deployment locations, content rules, and data-processing regions can differ. Check the target platform's live model list, price page, and rate-limit documentation before a production integration.
Are Accounts, Balances, and API Keys Shared?
Treat them as separate in practice. Zhipu's official setup documentation asks users to choose a BigModel or Z.ai account type, then enter the matching Base URL and API key. Do not assume that any of the following crosses platforms:
- Z.ai subscriptions or balances on BigModel;
- BigModel balances or Coding Plans on Z.ai;
- an API key created on one platform against the other platform's Base URL;
- subscriptions, refunds, or invoices managed by the other platform.
Even if you register with the same email address or phone number, that alone does not establish a merged account. Zhipu does not promise cross-platform portability for accounts, balances, or keys; sign in again and create or confirm a key on the target platform when switching.
How Does ChatGLM Fit In?
Zhipu's user-facing services can be understood as three product lines:
- ChatGLM (Zhipu Qingyan): an AI assistant primarily for general users in mainland China;
- BigModel: the developer and enterprise platform primarily for mainland China;
- Z.ai: an international platform combining an AI assistant, agents, APIs, and a Coding Plan.
The API and Coding Plan side of Z.ai is therefore the closer international counterpart to BigModel, while Z.ai's chat assistant is closer to an international version of ChatGLM. These are not interchangeable domains; they are entry points for different audiences and workflows.
Which Platform Should You Choose?
Individuals, companies, and developers in mainland China should start with BigModel; Z.ai serves international users, with availability, payment methods, and data rules depending on region and account.
Choose BigModel first if your product serves mainland China and needs RMB billing, domestic invoices, or local compliance workflows. Evaluate Z.ai for international users, USD billing, or an overseas data-processing entry point. General users in mainland China who only need chat should compare ChatGLM with other domestic AI assistants instead.
Pricing and Access from China
Z.ai primarily prices APIs and Coding Plans in USD, while BigModel primarily bills plans and balances in RMB; current prices, promotions, and quotas are set independently on each platform.