GLM-5.3 Fast

GLM-5.3 Fast is a higher-throughput serving variant of Z.AI's GLM-5.3, using the same weights so output quality matches the standard endpoint.

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compare models

input · usd / 1m tok

$2.10

output · usd / 1m tok

$6.60

context window

1mtokens

modalities · in → out

takes text in, gives text out

pricing

base api ratesusd per 1m tokens

input
$2.10
output
$6.60
cache read
$0.39

providers

Fireworks hosts GLM-5.3 Fast. Impossibl routes your request intelligently and handles failover automatically when a provider is down.

  • Fireworks

specifications

takes text in, gives text outzai/glm-5.3-fast

  • creatorZ.AI
  • model typeText generation
  • context window1,000,000 tokens
  • maximum outputnot published
  • input

    takes text in, gives text out

  • outputtext
  • tool callingnot verified
  • releasedaug 14, 2026
  • endpoint/v1/chat/completions

unknown means the public catalog does not establish that fact. a model's documented capabilities can differ from what a particular api supports. see the model documentation for integration details.

try it · your prompt, this model, live

# responses API
import os
from openai import OpenAI

client = OpenAI(
    api_key=os.environ["IMPOSSIBL_API_KEY"],
    base_url="https://api.impossibl.com/v1",
)

resp = client.responses.create(
    model="zai/glm-5.3-fast",
    input="",
)
print(resp.output_text)

edit the prompt, then run

benchmarks

benchmark results are not available for this model yet.

compare GLM-5.3 Fast with other models

frontier labs and open weights, best-ranked firstusd / 1m tok · in / out

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frequently asked questions

What is GLM-5.3 Fast?

GLM-5.3 Fast is a higher-throughput serving variant of Z.AI's GLM-5.3, using the same weights so output quality matches the standard endpoint. It targets agent loops that chain many model calls, keeping GLM-5.3's always-on thinking, reasoning-effort control, tool calling, and long-context inputs at faster speeds.

How much does GLM-5.3 Fast cost?

GLM-5.3 Fast costs $2.10 per million input tokens and $6.60 per million output tokens through the Impossibl API. Cache reads cost $0.39 per million tokens. All rates are in USD.

view the pricing table ↑

What is the context length of GLM-5.3 Fast?

GLM-5.3 Fast has a 1,000,000-token context window through the Impossibl API.

What inputs and outputs does GLM-5.3 Fast support?

GLM-5.3 Fast accepts text as input. GLM-5.3 Fast returns text.

How do I use GLM-5.3 Fast through an API?

GLM-5.3 Fast is available through the Impossibl API. Use zai/glm-5.3-fast as the model identifier with /v1/chat/completions. The quickstart explains how to create an API key and send your first request.

follow the api quickstart →

When was GLM-5.3 Fast released?

Z.AI released GLM-5.3 Fast on August 14, 2026.

this page describes GLM-5.3 Fast as listed by the impossibl public api. prices and availability come from that catalog, refreshed here every five minutes. this is an impossibl offering, not a comparison of independent hosting-provider quotes. model descriptions and release dates, where available, use the creator sources linked under the answers above.

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