GLM 5.3 Flash

reasoningmit320B / 18B

GLM 5.3 Flash is an open-weight 321B-parameter (18B active) reasoning model with a 1M context window, hosted by Reka. It is served as an OpenAI-compatible passthrough with native tool calling, structured outputs, logprobs, and streaming.

Context
1.0M
Max output
1.0M
Input price
$0.15/1M tokens
Output price
$0.5/1M tokens

Capabilities

Reasoning & Interaction
Reasoning
Tool Calling
Output Control
Structured Output
JSON Mode
Infrastructure
Streaming
Prompt Caching
Fine-tuning

Details

Model IDglm5.3-flash
Provider Reka AI
Creator Z.AI (Zhipu)
Familyglm
Licensemit
Statusactive
Typereasoning
Input modalitiestext, image
Output modalitiestext
Open weight—
Parameters320B / 18B
Architecture—
Context window1.0M tokens
Max input—
Max output1.0M tokens
Reasoning tokens—
Knowledge cutoff—
Release date—
Sourceofficial

Tools

Function Callingfunction_calling
Call external functions and APIs

Endpoints

Chat CompletionsPOST
Generate chat responses with messageshttps://api.reka.ai/v1/chat/completions

Pricing

Input
$0.15
Output
$0.5
Cache write
—
Cache read
$0.02
Batch in
—
Batch out
—

Family Comparison: glm

ModelContextMax outPricing
GLM 5.3 Flash1.0M1.0M$0.15$0.5
GLM 5.31.0M262K$1.17$3.96

API

GET/v1/models/reka/glm5.3-flash