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GLM 5.3

by Z.ai · Released 2026

Z.ai's GLM 5.3 with a 1,048,576-token context window, tool calling, and reasoning you can set to low, high or max. Text in, text out.

Z.ai — glm-5.3 logo
LLM Chat

GLM 5.3

Powered by Z.ai · General Language Model (GLM), Mixture-of-Experts

Context Window

1M

Parameters

MoE

Max Output

1M (shared with input)

Category

LLM Chat

Overview

GLM 5.3 is the newest model in Z.ai's GLM-5 family. Its headline feature is a 1,048,576-token context window, large enough to hold a whole codebase, a long contract bundle or hours of transcripts in one request, and it keeps multi-turn tool calling for agent loops.

GLM 5.3 always reasons before it answers. `reasoning_effort` sets how much: `low`, `high` or `max`, with `max` as the default. Reasoning tokens bill as output tokens. On CallMissed, `none` and `minimal` map to `low`, `medium` to `high` and `xhigh` to `max`, so any OpenAI-style value returns a 200.

For latency-sensitive work, send `reasoning_effort: "low"`. In our tests on a short phone-receptionist prompt, the first word arrived in about 0.9 seconds at `low` and about 3.5 seconds at the default `max`. The model is text-only; send images to a vision model such as Gemma 4 31B.

Pricing

MetricPrice
Input /1M tokens₹204.0000
Output /1M tokens₹640.0000

1 credit = ₹1 = $0.01 USD. Transparent per-call pricing — you pay only for what you call, with no seat fees or minimums.

Key Highlights

  • 1,048,576-token context window
  • Reasoning effort: low, high or max
  • Multi-turn tool calling
  • OpenAI-compatible, with streaming

Benchmarks

BenchmarkScore
Context1M
First word~0.9s
Tool CallingYes

Technical Details

  • Context window: 1,048,576 tokens
  • Reasoning always on: low / high / max (default max)
  • Reasoning tokens are billed as output tokens
  • Tool calling via OpenAI-compatible tools and tool_choice
  • Text input and output only

Strengths

  • Very large 1M context in a single request
  • Adjustable reasoning depth per request
  • Reliable tool calling for agent loops

Limitations

  • Always reasons, so it is slower than a direct-answer model
  • Default max effort can take several seconds before the first word
  • Text only: no image input
  • Paid plans only

Use Cases

Long-document analysisAgentic codingTool-using agentsResearch over large corpora

API Example

curl https://api.callmissed.com/v1/chat/completions \
  -H "Authorization: Bearer cm_YOUR_KEY" \
  -d '{"model": "glm-5.3", "reasoning_effort": "low", "messages": [{"role": "user", "content": "Summarise these meeting notes"}]}'

Endpoint: POST /v1/chat/completions · Model ID: glm-5.3

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