MODELS / Z.AI

GLM 5.3 Fast

Speed-optimized version of Z.AI’s GLM-5.3 agentic coding model, built for responsive, real-time workloads. It supports advanced coding, long-horizon task execution, testing, vulnerability discovery, and cybersecurity analysis, making it ideal for developer tools, coding agents,…

TEXTREASONINGREASONINGTOOL-USEIMPLICIT-CACHING
1.0M
CONTEXT WINDOW
262.1K
MAX OUTPUT TOKENS
$2.10
INPUT PRICE / 1M TOKENS
$6.60
OUTPUT PRICE / 1M TOKENS
QUICKSTART

Call it in one request.

OpenAI-compatible: change the base URL, and the setup is complete.

curl https://enterprise.blackbox.ai/v1/chat/completions \
  -H "Authorization: Bearer $BLACKBOX_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "model": "blackboxai/zai/glm-5.3-fast",
    "messages": [{ "role": "user", "content": "Hello!" }],
    "stream": true
  }'
SPECIFICATIONS

The full spec sheet.

Context, pricing, modalities, routing, and deployment: everything GLM 5.3 Fast supports, in one table.

MODEL ID
blackboxai/zai/glm-5.3-fast
DEVELOPED BY
Z.AI
MODEL TYPE
Text
RELEASED
Sep 2, 2026
CONTEXT WINDOW
1.0M
MAX OUTPUT TOKENS
262.1K
INPUT MODALITIES
text
OUTPUT MODALITIES
text
INPUT PRICE
$2.10 / 1M tokens
OUTPUT PRICE
$6.60 / 1M tokens
CACHE READ
$0.21 / 1M tokens
REASONING
Supported
DATA RETENTION
Standard retention
DEDICATED DEPLOYMENT
Enterprise · single-tenant
SUPPORTED PARAMETERS
max_tokenstemperaturestoptoolstool_choicereasoninginclude_reasoning