GPT 5.6 Luna vs GLM 5.3 Flash

Practical read: GLM 5.3 Flash costs about a sixth as much. One API key runs both.

No card required. Start with 1 million free tokens.

Side by side:

GPT 5.6 Luna compared with Z.ai: GLM 5.3 Flash
Attribute	GPT 5.6 Luna `openai/gpt-5.6-luna-az`	GLM 5.3 Flash `z-ai/glm-5.3-flash`
Price, 1M in + out	$1.48 Atlas Cloud, cheapest route	$0.26 Wafer, cheapest route
Best for		Low cost
Input / output, 1M	$0.21 / $1.27	$0.053 / $0.21
Cached input	$0.0211/1M	$0.015825/1M to $0.079125/1M
Context window	1.05M 1,050,000 tokens	1.05M 1,048,576 tokens
First token, p50	Measuring	0.72 s via FriendliAI
AI IQ	Unrated	IQ 119 #50 on AI IQ
Provider routes	1	32 with failover
Privacy	Varies by provider	Confidential E2EE and zero retention route
Recent route uptime range	not enough data	0.00% to 100.00%
Publisher	OpenAI	Z.AI
Modes	chat	chat
More detail	Overview	Overview Pricing Providers

Price adds one million input and one million output tokens on the cheapest route. Prices and speed change: see the monthly reports and run a small eval before you choose a default.

Test both with your agent

Paste this into Claude Code, Cursor or any coding agent.

Compare GPT 5.6 Luna and GLM 5.3 Flash in this project through TrustedRouter.

1. Read https://trustedrouter.com/docs/llms.txt
2. Point the OpenAI-compatible client at
   https://api.trustedrouter.com/v1 and read the key from
   TRUSTEDROUTER_API_KEY.
3. Run our eval prompts on openai/gpt-5.6-luna-az, then on z-ai/glm-5.3-flash.
4. Show me cost, latency and quality side by side before changing the default.

import os
from openai import OpenAI

client = OpenAI(
    base_url="https://api.trustedrouter.com/v1",
    api_key=os.environ["TRUSTEDROUTER_API_KEY"],
)
for model in ("openai/gpt-5.6-luna-az", "z-ai/glm-5.3-flash"):
    response = client.chat.completions.create(
        model=model,
        messages=[{"role": "user", "content": "What is the capital of France?"}],
    )
    print(model, response.choices[0].message.content)

for model in openai/gpt-5.6-luna-az z-ai/glm-5.3-flash; do
  curl https://api.trustedrouter.com/v1/chat/completions \
    -H "Authorization: Bearer $TRUSTEDROUTER_API_KEY" \
    -H "Content-Type: application/json" \
    -d "{\"model\": \"$model\", \"messages\": [{\"role\": \"user\", \"content\": \"What is the capital of France?\"}]}"
done

Your agent will need an API key.

Questions

Which should I use, GPT 5.6 Luna or Z.ai: GLM 5.3 Flash?

GPT 5.6 Luna has the larger context window. Z.ai: GLM 5.3 Flash has the lower published input-plus-output rate and more Credits provider routes. There is not enough recent probe data to compare speed.

Is GPT 5.6 Luna or Z.ai: GLM 5.3 Flash cheaper?

The current cheapest TrustedRouter route is $1.477/1M for GPT 5.6 Luna and $0.26375/1M for Z.ai: GLM 5.3 Flash. The comparison uses current catalog prices and updates as provider pricing changes.

Is GPT 5.6 Luna or Z.ai: GLM 5.3 Flash faster?

Current measured p50 time to first token is not enough data for GPT 5.6 Luna and 719 ms for Z.ai: GLM 5.3 Flash. These are routed probe measurements, not vendor-advertised speeds, and update as new samples arrive.

Can I test GPT 5.6 Luna and Z.ai: GLM 5.3 Flash with the same API?

Yes. Use the same OpenAI-compatible TrustedRouter base URL and API key, then change only the model id between openai/gpt-5.6-luna-az and z-ai/glm-5.3-flash. This makes side-by-side evals possible without maintaining two provider integrations.

More comparisons

All comparisons

Try GPT 5.6 Luna and GLM 5.3 Flash with one key.

TrustedRouter is useful when you know the model you want, but still need provider rollover, budget limits, usage records, and a prompt path you can verify.

No card required. Start with 1 million free tokens.