OpenAI GPT OSS vs Kimi K3.1 Pro

Practical read: OpenAI GPT OSS costs about an eighth as much and starts answering sooner. Kimi K3.1 Pro reads eight times more context. One API key runs both.

No card required. Start with 1 million free tokens.

Side by side:

OpenAI GPT OSS compared with MoonshotAI: Kimi K3.1 Pro
Attribute	OpenAI GPT OSS `cerebras/gpt-oss-120b`	Kimi K3.1 Pro `moonshotai/kimi-k3.1-pro`
Price, 1M in + out	$1.16 Cerebras, cheapest route	$8.86 Engy, cheapest route
Best for	Low cost and speed	Long documents
Input / output, 1M	$0.37 / $0.79	$1.48 / $7.38
Cached input	Not published	$0.1477/1M to $0.422/1M
Context window	131K 131,072 tokens	1.05M 1,048,576 tokens
First token, p50	0.50 s via Cerebras	0.59 s via Telnyx
AI IQ	IQ 98 #136 on AI IQ	IQ 132 #14 on AI IQ
Provider routes	1	15 with failover
Privacy	Zero retention route	Confidential E2EE and zero retention route
Recent route uptime range	100.00%	100.00%
Publisher	Not stated	Kimi
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 OpenAI GPT OSS and Kimi K3.1 Pro 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 cerebras/gpt-oss-120b, then on moonshotai/kimi-k3.1-pro.
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 ("cerebras/gpt-oss-120b", "moonshotai/kimi-k3.1-pro"):
    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 cerebras/gpt-oss-120b moonshotai/kimi-k3.1-pro; 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, OpenAI GPT OSS or MoonshotAI: Kimi K3.1 Pro?

OpenAI GPT OSS has the lower published input-plus-output rate and the lower measured p50 time to first token. MoonshotAI: Kimi K3.1 Pro has more Credits provider routes and the larger context window.

Is OpenAI GPT OSS or MoonshotAI: Kimi K3.1 Pro cheaper?

The current cheapest TrustedRouter route is $1.1605/1M for OpenAI GPT OSS and $8.862/1M for MoonshotAI: Kimi K3.1 Pro. The comparison uses current catalog prices and updates as provider pricing changes.

Is OpenAI GPT OSS or MoonshotAI: Kimi K3.1 Pro faster?

Current measured p50 time to first token is 502 ms for OpenAI GPT OSS and 594 ms for MoonshotAI: Kimi K3.1 Pro. These are routed probe measurements, not vendor-advertised speeds, and update as new samples arrive.

Can I test OpenAI GPT OSS and MoonshotAI: Kimi K3.1 Pro with the same API?

Yes. Use the same OpenAI-compatible TrustedRouter base URL and API key, then change only the model id between cerebras/gpt-oss-120b and moonshotai/kimi-k3.1-pro. This makes side-by-side evals possible without maintaining two provider integrations.

More comparisons

All comparisons

Try OpenAI GPT OSS and Kimi K3.1 Pro 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.