Kimi K3.1 Pro vs Fugu Ultra v1.1

Kimi K3.1 Pro and Fugu Ultra v1.1 side by side: specs, capabilities, parameters, and live pricing from the EmpirioLabs catalog.

Moonshot AI Sakana AI Text Generation

Kimi K3.1 Pro vs Fugu Ultra v1.1 at a glance

Kimi K3.1 Pro from Moonshot AI and Fugu Ultra v1.1 from Sakana AI are both in the Text Generation category, available through the EmpirioLabs API.

Key differences

  • Kimi K3.1 Pro is the newer release (Oct 23, 2026); Fugu Ultra v1.1 was released on Jul 23, 2026.
  • Both models have a context window of 1M tokens.
  • Capabilities listed only for Kimi K3.1 Pro: vision.
  • Capabilities listed only for Fugu Ultra v1.1: web search.

Kimi K3.1 Pro vs Fugu Ultra v1.1: specs

SpecKimi K3.1 ProFugu Ultra v1.1
Model IDkimi-k3-1-profugu-ultra-v1-1
AuthorMoonshot AISakana AI
ReleasedOct 23, 2026Jul 23, 2026
Context window1M tokens1M tokens
Max output131,072 tokens131,072 tokens
Input
Text Image
Text Image
Output
Text
Text
Structured outputJSON SchemaJSON Schema
RegionGermany-
Endpoints
POST /v1/chat/completions POST /v1/responses POST /v1/messages POST /v1beta/models/kimi-k3-1-pro:generateContent
POST /v1/chat/completions POST /v1/responses POST /v1/messages POST /v1beta/models/fugu-ultra-v1-1:generateContent
Capabilities
reasoning function calling multimodal vision agentic coding cache
reasoning multimodal web search function calling agentic coding cache

Kimi K3.1 Pro vs Fugu Ultra v1.1: API pricing

Live rates from the EmpirioLabs catalog for both models. Each rate card always matches what the API charges.

Kimi K3.1 Pro vs Fugu Ultra v1.1: API parameters

Request parameters each model lists on EmpirioLabs, with the allowed values or range where one applies. A dash marks a parameter the model does not list.

ParameterKimi K3.1 ProFugu Ultra v1.1
max_tokens1 to 131072 Default: 13107216 to 131072
stopstring-
enable_thinkingboolean Default: true-
reasoning_effortlow, medium, high, max Default: maxhigh, xhigh, max Default: high
response_formatenumenum
web_search_linkupboolean Default: false-
disable_formattingboolean Default: false-
tool_web_search-boolean Default: false
tools-array Default: []
tool_choice-object

Kimi K3.1 Pro vs Fugu Ultra v1.1: limits and notes

Kimi K3.1 Pro

Supports text and image inputs with a 1M token context, function calling, and JSON schema structured output. Linkup web search is available through web_search_linkup and adds $0.013 per call when invoked. Thinking is on by default: set its depth with reasoning_effort (max is the default), or turn it off with enable_thinking, which lowers output quality. Reasoning tokens are billed as output tokens. Stop strings apply to reasoning as well as the answer, so a stop string that appears in the reasoning ends the reply early. Temperature and other sampling settings are fixed by the model service.

Fugu Ultra v1.1

Fugu Ultra v1.1 is an updated multi-agent conductor: each request coordinates a pool of expert models and composes their work into a single answer.

Latency and streaming

  • Responses can take from a few seconds to a few minutes on complex prompts.
  • The full answer is returned all at once when the model finishes, not token by token. Streaming is accepted, but it delivers the complete response at the end rather than streaming tokens as they generate.
  • max_tokens must be at least 16. Leave generous headroom, since very small limits can truncate or empty the answer.

Capabilities

  • Text and image input, with a 1M token context.
  • Always-on reasoning with high, xhigh, and a distinct max level for the hardest problems.
  • Function calling, strict JSON Schema structured output, and built-in web search that cites its sources when available (no separate fee).

Versioning

  • Use fugu-ultra-v1-1 for v1.1. The legacy fugu-ultra id remains pinned to v1.0 for backward compatibility.

Billing

  • Billed on full token usage, including the orchestration tokens the model uses internally, so even short prompts carry some cost.
  • Context-tiered: requests above 272K total input tokens use the higher rate shown.

How to call Kimi K3.1 Pro and Fugu Ultra v1.1

Kimi K3.1 Pro serves the OpenAI-compatible Chat Completions API. Point any OpenAI SDK at https://api.empiriolabs.ai/v1 with your EmpirioLabs API key and use the model id kimi-k3-1-pro. Both models are called through the same endpoint. Set model to kimi-k3-1-pro or fugu-ultra-v1-1. Get an API key from the EmpirioLabs dashboard.

cURL
curl https://api.empiriolabs.ai/v1/chat/completions \
  -H "Authorization: Bearer $EMPIRIOLABS_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "model": "kimi-k3-1-pro",
    "messages": [
      {"role": "user", "content": "Write a haiku about the ocean."}
    ]
  }'

Kimi K3.1 Pro vs Fugu Ultra v1.1: common questions

What is the difference between Kimi K3.1 Pro and Fugu Ultra v1.1?

Kimi K3.1 Pro is the newer release (Oct 23, 2026); Fugu Ultra v1.1 was released on Jul 23, 2026. Both models have a context window of 1M tokens. Capabilities listed only for Kimi K3.1 Pro: vision. The specs, rate cards, and parameters on this page come from the live EmpirioLabs catalog.

Which is newer, Kimi K3.1 Pro or Fugu Ultra v1.1?

Kimi K3.1 Pro is the newer release (Oct 23, 2026); Fugu Ultra v1.1 was released on Jul 23, 2026.

Which has the lower rate, Kimi K3.1 Pro or Fugu Ultra v1.1?

The two models are priced on different units or tiers, so compare the live rate cards on this page. They always match what the API charges.

Can I switch between Kimi K3.1 Pro and Fugu Ultra v1.1 without rebuilding my integration?

Yes. Both models use POST /v1/chat/completions with the same EmpirioLabs API key, so most integrations switch by changing the model value. Check the parameters table on this page first if you rely on a model-specific parameter.

Can I try Kimi K3.1 Pro and Fugu Ultra v1.1 in the browser before integrating?

Yes. Open each model in the EmpirioLabs playground and run the same prompt on both, with the parameters the API exposes.

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