GLM 5.2 Fast
GLM 5.2 Fast is a faster-serving variant of GLM-5.2, Z.AI's flagship long-horizon coding model, released June 23, 2026. Same weights and 1M tokens context, served on inference infrastructure tuned for higher throughput.
View API reference- Input and output price
- Prices from: Input $2.10, Output $6.60, Per 1M tokens
- 24h uptime
- Loading AI Gateway uptime
import { streamText } from 'ai'
const result = streamText({ model: 'zai/glm-5.2-fast', prompt: 'Why is the sky blue?'})Copy link to headingPlayground
Try out GLM 5.2 Fast by Z.AI. Usage is billed to your team at API rates. Free users (those who haven't made a payment) get $5 of credits every 30 days.
GLM 5.2 Fast
GLM 5.2 Fast
Copy link to headingProviders
Route requests across multiple providers. Copy a provider slug to set your preference. Visit the docs for more info. Using a provider means you agree to their terms, listed under Legal.
Copy link to headingUptime24 hours
Direct request success rate on AI Gateway and per-provider. Visit the docs for more info.
Copy link to headingThroughput24 hours
P50 throughput on live AI Gateway traffic, in tokens per second (TPS). Visit the docs for more info.
Copy link to headingLatency24 hours
P50 time to first token (TTFT) on live AI Gateway traffic, in milliseconds. View the docs for more info.
Getting started
Call GLM 5.2 Fast through AI Gateway with the AI SDK generateText and streamText functions, or through the OpenAI Chat Completions, OpenAI Responses, and Anthropic Messages APIs by changing the base URL. AI Gateway authenticates the request and routes it to an available provider.
Install the AI SDK (pnpm add ai dotenv), create an API key from the API Keys page, and set it as AI_GATEWAY_API_KEY in your environment. Full setup is covered in the text generation quickstart.
import { generateText } from 'ai';import 'dotenv/config';
async function main() { const result = await generateText({ model: 'zai/glm-5.2-fast', prompt: 'Why is the sky blue?', });
console.log(result.text);}
main().catch(console.error);Top-level parameters
The same GLM 5.2 Fast request in each API format AI Gateway supports.
import { generateText } from 'ai';import 'dotenv/config';
async function main() { const result = await generateText({ model: 'zai/glm-5.2-fast', system: 'You are a concise technical assistant.', prompt: 'Summarize the tradeoffs between static generation and SSR.', maxOutputTokens: 1024, });
console.log(result.text);}
main().catch(console.error);Standard parameters like prompt, messages, temperature, and tools work as documented in the AI SDK docs. These are the parameters with model-specific behavior.
| Parameter | Type | Required | Description |
|---|---|---|---|
model | string | Yes | Model ID in the form creator/model, e.g. zai/glm-5.2-fast. AI Gateway routes the request to an available provider. |
maxOutputTokens | number | No | Hard cap on generated tokens. GLM 5.2 Fast supports up to 128,000 output tokens. Reasoning tokens count toward this limit. |
reasoning | 'provider-default' | 'none' | 'minimal' | 'low' | 'medium' | 'high' | 'xhigh' | No | Provider-agnostic reasoning effort, available in AI SDK 7 or later. Maps to the provider’s native reasoning configuration; reasoning settings under providerOptions take precedence when both are set. See the Reasoning section below. |
providerOptions | Record<string, JSONValue> | No | AI Gateway routing options under gateway, plus any provider-native options under the provider’s own namespace — see the table below. |
Input limits
| Input | Formats | Sources | Max count | Max size | Limits |
|---|---|---|---|---|---|
| Text | — | — | — | — | Prompt and response share the 1M-token context window |
Provider options
Set AI Gateway routing options under providerOptions.gateway. For provider-specific options, pass them under the provider’s namespace as documented by the AI SDK.
Learn more in the AI SDK provider docs.
import { generateText } from 'ai';import 'dotenv/config';
async function main() { const result = await generateText({ model: 'zai/glm-5.2-fast', prompt: 'Why is the sky blue?', providerOptions: { gateway: { only: ['fireworks', 'baseten'], }, }, });
console.log(result.text);}
main().catch(console.error);These AI Gateway routing options apply to every model. Provider-specific options pass through under the provider’s own namespace (for example providerOptions.anthropic) exactly as documented by the AI SDK.
| Parameter | Type | Required | Description |
|---|---|---|---|
providerOptions.gateway.only | string[] | No | Restrict routing to these provider slugs. Requests fail over only within the listed providers. |
providerOptions.gateway.order | string[] | No | Preferred provider order. Listed providers are tried first; unlisted providers remain available as fallbacks. |
providerOptions.gateway.sort | 'cost' | 'ttft' | 'tps' | No | Rank candidate providers by price, time to first token, or tokens per second instead of the default routing order. |
providerOptions.gateway.zeroDataRetention | boolean | No | Route only to providers with a zero-data-retention policy for this model. |
Routing across providers
AI Gateway serves the same model through multiple providers and fails over automatically. order expresses a preference while keeping every provider eligible; only is a hard allowlist — if none of the listed providers are available the request fails instead of falling back.
Options under a provider's own namespace (for example providerOptions.anthropic) are forwarded to that provider with the request. Providers ignore option namespaces that don't apply to them, so it is safe to set provider options alongside gateway routing options.
Reasoning
AI Gateway bridges reasoning across every API format. The AI SDK exposes a provider-agnostic top-level reasoning level (none, minimal, low, medium, high, or xhigh); the Chat Completions and Responses formats take the same effort under reasoning.effort; and the Anthropic Messages format uses a native thinking token budget. Whichever you send, the gateway maps it to the target model’s native configuration, converting between effort levels and token budgets as needed. Reasoning-related settings under providerOptions take full precedence over the top-level reasoning value and are never merged. Reasoning tokens typically count toward your output-token usage, though how they’re reported and billed varies by provider.
Learn more in the AI Gateway reasoning guide.
import { generateText } from 'ai';import 'dotenv/config';
async function main() { const result = await generateText({ model: 'zai/glm-5.2-fast', prompt: 'Explain the Monty Hall problem step by step.', reasoning: 'high', });
console.log(result.text);}
main().catch(console.error);Tool calling
Expose tools the model can call. Define each tool’s inputs with a Zod schema.
import { generateText, tool } from 'ai';import { z } from 'zod';import 'dotenv/config';
async function main() { const result = await generateText({ model: 'zai/glm-5.2-fast', prompt: 'What is the weather in San Francisco?', tools: { getWeather: tool({ description: 'Get the current weather for a location', inputSchema: z.object({ location: z.string() }), execute: async ({ location }) => ({ location, temperatureC: 18 }), }), }, });
console.log(result.text);}
main().catch(console.error);Copy link to headingMore models by Z.AI
| Model |
|---|
| 1M | 0.3 s | 212 tps | $0.07/M | $0.24/M | Read$0.01/M | — | +1 |    +15 | 08/26/2026 | |||||
| 1M | 0.1 s | 287 tps | $0.70/M+1 more | $2.20/M+1 more | Read$0.12/M | — |   +15 | 08/18/2026 | ||||||
| 1M | 0.2 s | 590 tps | $0.70/M+1 more | $2.20/M+1 more | Read$0.11/M | — |  +15 | 06/16/2026 | ||||||
| 205K | 1.7 s | 53 tps | $1.40/M | $4.40/M | Read$0.26/M | — |  | 04/07/2026 | ||||||
| 203K | 0.3 s | 190 tps | $1/M | $3.20/M | Read$0.20/M | — |  | 02/12/2026 | ||||||
| 205K | 0.1 s | 183 tps | $0.43/M | $1.75/M | Read$0.08/M | — | +2 | 12/22/2025 |
Copy link to headingAbout GLM 5.2 Fast
GLM 5.2 Fast was released June 23, 2026 as the faster-serving variant of GLM-5.2, Z.AI's flagship model for long-horizon coding and agentic engineering. GLM 5.2 Fast runs the same underlying weights, so output quality matches the standard glm-5.2 endpoint. The difference is the serving stack: providers behind GLM 5.2 Fast run inference infrastructure tuned for higher throughput, and AI Gateway publishes live throughput and latency metrics on this page.
Everything that defines GLM-5.2 carries over. You get the 1M tokens context window, thinking on or off per request, selectable reasoning effort, tool calling, structured output, streaming, and implicit caching. Agent loops benefit the most: when a task chains dozens of model calls, faster serving shortens every step, and the savings compound across the whole run.
Speed comes at a higher per-token rate than the standard endpoint, so most teams split traffic. Interactive and user-facing paths route to GLM 5.2 Fast, while batch and background jobs stay on glm-5.2. Both share the same API surface through AI Gateway, so switching is a one-line model identifier change. The AI SDK, Chat Completions API, Responses API, Messages API, and other API formats all work.
Copy link to headingWhat To Consider When Choosing a Provider
- Configuration: Quality is identical to
glm-5.2because the weights are the same. Choose between the two on serving characteristics and cost, not capability. Check the live throughput and latency metrics on this page and on theglm-5.2page before committing traffic. - Configuration: Per-token rates run higher than the standard endpoint. Route interactive, latency-sensitive paths here and keep batch or overnight jobs on
glm-5.2to control spend. - Configuration: Reasoning effort still applies. A high effort setting spends more tokens and time regardless of serving speed, so tune effort per task instead of relying on fast infrastructure to absorb deep deliberation.
- Zero Data Retention: Zero Data Retention is available for this model. It is offered on a per-provider and model basis. See the documentation for details.
- Authentication: AI Gateway authenticates requests using an API key or OIDC token. You do not need to manage provider credentials directly.
Copy link to headingWhen to Use GLM 5.2 Fast
Best for
- Interactive Coding Agents: Editor and terminal agents where users wait on every response
- Multi-Step Agent Loops: Chained tool calls where per-step speed compounds across the run
- User-Facing AI Products: Chat and assistant features that need GLM-5.2-class quality without long pauses
- Rapid Iteration Workflows: Tight edit-test-fix cycles that keep developers in flow
Consider alternatives when
- Batch or Background Jobs:
glm-5.2delivers identical output quality at lower per-token cost - High-Volume Lightweight Tasks: GLM-5-Turbo handles extraction and classification workloads economically
- Vision or GUI Input: GLM-5V-Turbo adds screenshot and image understanding to the GLM-5 generation
- Maximum Cost Efficiency: GLM-4.7-Flash covers simple prompts when GLM-5.2-class capability is unnecessary
Copy link to headingConclusion
GLM 5.2 Fast removes the usual speed-versus-quality tradeoff for GLM-5.2 workloads: same weights, faster serving. Route latency-sensitive traffic here, keep batch work on glm-5.2, and let AI Gateway's live metrics and unified API make the split a one-line decision.
Copy link to headingFrequently Asked Questions
How does GLM 5.2 Fast differ from GLM 5.2?
GLM 5.2 Fast runs the same weights as
glm-5.2on inference infrastructure tuned for higher throughput, at different per-token rates. Output quality is identical; serving speed and price are the differences. See the live metrics on this page for current numbers.How fast is GLM 5.2 Fast?
Throughput varies by provider and load, so check the live throughput and latency metrics on this page for current numbers. Providers behind GLM 5.2 Fast run serving stacks tuned specifically for speed.
What is the context window for GLM 5.2 Fast?
1M tokens.
Can I switch between GLM 5.2 Fast and GLM 5.2?
Yes. Both share the same API surface through AI Gateway. Swap the model identifier between the two endpoints and nothing else in your integration needs to change.
Does GLM 5.2 Fast support reasoning?
Yes. GLM 5.2 Fast inherits GLM-5.2's thinking toggle and reasoning effort levels, along with tool calling, structured output, and implicit caching.
What is the pricing for GLM 5.2 Fast?
Check the pricing panel on this page for today's numbers. AI Gateway tracks rates across every provider that serves GLM 5.2 Fast.
Does GLM 5.2 Fast support Zero Data Retention?
Yes, Zero Data Retention is available for this model. Zero Data Retention is offered on a per-provider basis. See https://vercel.com/docs/ai-gateway/capabilities/zdr for details.
How do I access GLM 5.2 Fast through AI Gateway?
Use the
zai/glm-5.2-fastmodel identifier with your AI Gateway API key via the AI SDK, the Chat Completions API, the Responses API, the Messages API, or other API formats. No separate Z.AI account is needed. BYOK is also supported.