Z.ai — an independent reference on Zhipu AI's open platform and the GLM model family

Model variants, the BigModel open platform, the ChatGLM chat lineage, license footprint, and the broader developer ecosystem in one organised reference. Built for engineers, researchers, and product teams evaluating the Z.ai surface.

GLM-4.5+

Current generation

100B+

Flagship parameters

128K

Context window

26+

Languages

Open weights Permissive license BigModel platform ChatGLM heritage Multilingual coverage OpenAI-compatible API
Three lenses on Z.ai

Browse by topic — pick the lens that matches your question

GLM-4 family

The flagship general-purpose chat models in the GLM lineage, including the latest GLM-4.5+ generation with extended context windows.

ChatGLM

The original open-weight chat model lineage from Zhipu AI that established the family and remains the most-downloaded community variant.

GLM Coder

The code-specialised branch fine-tuned on a curated programming corpus, with strong HumanEval and MBPP coverage at small parameter classes.

Z.ai chat surface

The browser-based chat experience, free for casual use, with model switching across the GLM family and saved conversation history for signed-in accounts.

BigModel API

The OpenAI-compatible API endpoint for programmatic access. An existing OpenAI SDK switches to BigModel with a one-line base URL change.

Open platform console

The BigModel console for billing, key management, model selection, prompt-history review, and dashboards on usage by project.

Weight downloads

ChatGLM and most GLM open-weight builds are on Hugging Face. Quantised community mirrors cover the smaller variants for laptop inference.

Pricing reference

The BigModel platform meters per-token. The pricing page on this site walks through the typical cost classes per model and per request type.

GitHub presence

The Zhipu AI GitHub organisation hosts inference code, fine-tuning recipes, evaluation harnesses, and the model cards that surround each release.

Six product surfaces covered on this site

A direct map from each Z.ai product surface to its dedicated reference page on this domain.

GLM model family

The general-purpose chat lineage. Pages cover GLM-4, the latest GLM-4.5+ generation, and the parameter sweep at each release.

Open GLM model reference →

ChatGLM open-weights

The original ChatGLM lineage that put the lab on the open-weight map. The most-cloned variant for local inference experiments.

ChatGLM reference →

Z.ai chat surface

The browser-based chat experience. Free for casual use, with model switching and conversation history when signed in.

Chat reference →

Zhipuai API

The OpenAI-compatible programmatic interface. Switching from the OpenAI SDK is a one-line base_url change in any modern client.

API reference →

BigModel open platform

The hosted developer console with billing, key management, model selection, and prompt history. The canonical management surface for production use.

Open platform reference →

English access

How to use Z.ai entirely in English — interface language, English-tuned outputs, and where the Chinese-first defaults can trip up an outside team.

English reference →

What practitioners say about working with Z.ai

A short selection of perspectives from researchers and engineers building with the GLM family and the BigModel platform.

"For a Chinese-language workload that also needs strong English coverage, the GLM family has consistently led our internal scoreboards. Z.ai made the procurement conversation a one-paragraph review."
Aurelio M. Vandersteen
AI Researcher · Quartermast Modeling Lab · Cambridge, MA
"The BigModel API mirrors the OpenAI surface so closely that I redirected three internal services in a single afternoon. The cost-per-token profile justified the swap before the next sprint review."
Sabine R. Pohorecky
ML Engineer · Ravenscar Compute Network · Pittsburgh, PA
"ChatGLM was the first open-weight chat model that did not need an apology. Years later, the GLM lineage still ships releases on a cadence that rewards readers who track the model cards weekly."
Kwabena T. Asante-Mensah
Solutions Architect · Hollowfield Stack Group · Atlanta, GA
"Multilingual evaluation work has historically over-indexed on English. The GLM family is one of the few where Mandarin and English coverage both clear our internal bar without separate fine-tuning passes."
Indira P. Krishnaswami
Research Lead · Marlinridge Cognitive Studio · Princeton, NJ

How the cluster of Z.ai topics fits together

Two short paragraphs explain how the various Z.ai surfaces connect, with direct links into each topic page on this site.

For a reader landing here cold, the practical model is this: Z.ai is the modern public-facing brand for what was historically called Zhipu AI. The chat surface is reachable through both the Z.ai domain and the legacy paths, and the action of chatting with Z.ai is identical to using the upstream Zhipu AI chat. Underneath the chat is the ChatGLM lineage, the foundation of the broader GLM AI model family that ships across multiple parameter classes. For programmatic use, the Zhipuai API is the OpenAI-compatible endpoint exposed by the Zhipu AI open platform, and the BigModel AI branding is the legacy console name many engineers still know it by.

Around those primary surfaces, several supporting pages cover the secondary topics. The Zhipuai login flow is the same account that unlocks the chat history, the API key console, and the project-level analytics. The Zhipu AI pricing page documents the per-token tiers across the model classes; the Zhipu AI GitHub presence hosts the inference code, the model cards, and the evaluation harnesses; and the Zhipuai download path is where to grab the open-weight ChatGLM and GLM builds for self-hosted deployments. Read the pages in any order — each stands alone, but the cross-links keep adjacent topics one click away.

Frequently asked questions

Seven questions across three topical tabs cover the territory most readers want answered before exploring the individual reference pages.

What is Z.ai?

Z.ai is the modern public-facing brand of Zhipu AI, a Chinese AI research lab. The Z.ai surface fronts the GLM model family, the ChatGLM chat lineage, and the BigModel open platform — all of which can be accessed through the same account and API contract.

How is Z.ai related to Zhipu AI?

Z.ai is the same product surface as Zhipu AI under updated branding. The chat experience, API endpoints, and model catalog continue to live on the BigModel open platform; only the customer-facing brand and domain have been refreshed.

Is Z.ai free to use?

The Z.ai chat surface offers a free tier for casual use. Programmatic access through the BigModel API has a free trial credit followed by usage-based pricing. The open-weight ChatGLM and GLM model builds can be downloaded and run locally without any subscription.

What models does the GLM family include?

The GLM family spans general-purpose chat models (GLM-4, GLM-4.5+), the open-weight ChatGLM lineage, and code-specialised variants. Each generation refreshes the parameter sweep, context window, and multilingual coverage. The GLM model page walks through which variant fits which workload.

What is ChatGLM?

ChatGLM is the original open-weight chat model lineage from Zhipu AI that put the lab on the global open-weight map. It set the template that the broader GLM family extended into multimodal and reasoning-tuned territory. The ChatGLM reference covers the open-weight builds and the typical local-inference workflow.

Can I download GLM weights?

Yes. ChatGLM and most GLM open-weight builds are published on Hugging Face and on the project's GitHub organisation under permissive licenses. Quantised community mirrors run the smaller variants on consumer hardware via mainstream inference engines.

Where is the Z.ai API documented?

The BigModel open platform hosts the canonical Z.ai API documentation. The contract is OpenAI-compatible at the chat-completions level, so an existing OpenAI SDK can be repointed at the BigModel base URL with a one-line change. Public-research orientation guidance from NIST is useful background for any team formalising its AI evaluation process before a production rollout.

Why a reference site for Z.ai — and why now

The Z.ai brand merges several historically distinct names — Zhipu AI, ChatGLM, GLM, BigModel — into a single coherent surface. An organised public reference helps developers, researchers, and product teams orient themselves quickly without chasing the legacy names.

Two years ago, evaluating an open-weight LLM family from a Chinese research lab meant tracking three separate surfaces — an academic GitHub organisation, a Hugging Face mirror, and a commercial API portal — that did not always agree about model availability or licensing terms. Today, the cluster around what is now publicly branded as Z.ai has consolidated. The chat experience, the API console, the open-weight model cards, and the developer documentation all roll up to the same account and the same billing surface. That consolidation is genuinely useful for an outside team trying to commit to the family, and it is the right moment for a reader-first reference to summarise the landscape.

This site is the response. It is an independent reader-first resource that summarises publicly published Z.ai materials in plain language and organises them by reader intent. A developer who lands here from "zhipuai api" gets a page that explains the API contract, the OpenAI-compatible base URL pattern, and the BigModel pricing surface. A researcher who lands from "chatglm" gets a focused brief on the open-weight lineage and where the latest generation differs from the original. A product manager who lands from "zhipu ai pricing" gets the per-token tiers and the practical cost classes for everyday workloads.

What we explicitly do not do

We do not host Z.ai weights. We do not proxy inference through this domain. We do not redistribute paywalled or pre-print content. Where a topic touches a license question or a research claim, we link to the canonical source — the model card on Hugging Face, an arXiv paper, a research blog post hosted by the upstream team, or a public benchmark leaderboard. Those external links are kept few and load-bearing. The footer on every page reiterates that this domain is an independent reference and not the official Z.ai company website.

The shape of the ecosystem around the GLM family

Open-weight model lines that ship aggressively reward readers who know which release to track for which workload, and the GLM family has been one of the most aggressive on cadence in the post-2024 wave.

Open-weight LLM teams operate on different cadences. Some ship a single flagship every nine months and then iterate quietly. Others release a new generation every quarter. The Z.ai team sits firmly in the second camp: chat generations, code-specialised generations, and multimodal generations have rolled out with overlapping cadences, and the parameter sweep at each release usually spans a small variant suitable for laptop inference, a mid-size variant suitable for a single high-end GPU, and a flagship size that requires hosted inference. The smaller variants are routinely used by individual developers; the larger ones show up in academic benchmark comparisons and on public leaderboards.

For a small-team build, the practical takeaway is that the right Z.ai variant for your workload almost certainly exists today, but it might not be the one with the most marketing attention. The mid-size class is genuinely production-ready for many workloads; the flagship is where the long-form quality bar starts to feel inevitable for outside-China use cases. The benchmarks page walks through which class to pick for which workload type, with the caveat that any benchmark snapshot ages in months.

For an enterprise build, the more important question is the license footprint and the operational fit. Open-weight does not always mean Apache 2.0; some GLM releases ship under custom licenses tuned for the family. The open platform reference walks through the practical implications without converting it into legal advice. Public-research orientation guidance from Stanford CRFM is useful background reading for any team formalising its model-evaluation process before a production rollout.

How this site organises 30 Z.ai reference pages

Three topical silos for the substantive content, six generic-information hubs for the editorial side, four keyword-landing pages for high-intent searches, and one privacy-policy page.

The first silo is Models. It covers the GLM AI model framing at the family level, the ChatGLM lineage, the broader Zhipu AI LLM positioning, an ai-model overview for readers who land without a specific variant in mind, the latest-release summary, and the public benchmarks coverage. Each of those pages stands alone — a reader who lands directly from search gets a complete answer there — and they cross-link so a reader who wants to dig further has somewhere to go next.

The second silo is Access & Tools. It covers the ways a developer can actually run a Z.ai workload: the chat surface for "chat z ai" workflows, the broader Zhipu AI chat product framing, the OpenAI-compatible Zhipuai API, the chatbot interface for casual users, the Zhipuai login flow as a transactional keyword-landing page, and the BigModel-hosted Zhipu AI open platform that ties everything together at the management layer.

The third silo is Resources & Ecosystem. It covers the BigModel platform, the Zhipuai download path for self-hosted use, the Zhipu AI pricing tiers, the GitHub organisation, English-first access patterns for outside-China teams, and broader integration tooling. Surrounding the silos are six generic-information hubs (renamed for site-uniqueness) and four keyword-landing pages that catch the high-intent searches that do not slot cleanly into a silo — including an official-site clarifier, a broader Z.ai models catalog overview, a Z.ai vs ChatGPT comparison, and a Z.ai mobile-app entry. A privacy policy rounds out the set.

Notes specifically for teams based outside mainland China

Some of the friction outside teams hit when adopting open platforms from Chinese labs is operational rather than technical. A short orientation pays for itself.

Three operational items recur for outside teams more often than the technical questions. The first is account registration. Most outside developers will sign up for the BigModel console with an international email address; the verification flow expects a phone number that can receive an SMS, and the accepted country list has expanded substantially over the past year. Most modern phone numbers from Western Europe, North America, and major Asia-Pacific markets work without intervention.

The second is payment. The platform accepts a growing roster of international payment methods, including major credit-card networks, but the per-token billing is denominated in CNY at the underlying tier and converted at the gateway. For procurement teams that want a hard USD budget, the right pattern is to pre-load a credit balance in CNY equivalent rather than to commit to a per-period invoice; most teams that adopt this approach find the cost predictability matches their internal financial controls.

The third is the language defaults. The hosted chat surface and the documentation portal both still default to Chinese for first-time visitors, with an English toggle near the top of each surface. Once the toggle is set, it persists across the account; for read-once visitors arriving from search, the English-access page on this site walks through the toggle locations and the small handful of strings that have not yet been fully localised.