Fugu Ultra v2
Access Sakana AI's Fugu Ultra v2 through one API key. The top tier of the Fugu multi-agent system.
Sakana AI's higher-performance Fugu model. A learned multi-agent orchestration system that routes work across stronger specialist models, with a 1M token context window and 128K output tokens.
No credit card required. Takes 30 seconds.
2,400+
Developers
1.2M+
API calls served
100+
Endpoints
$0.01
Per call
Yep, that's it.
Try it live
Send a message and see Fugu Ultra v2 respond in real time.
Maximum tokens in the response.
Real-time tokens
Context Window
1M tokens
Max Output
128K tokens
Input Price
$7.00 / 1M tokens
Output Price
$42.00 / 1M tokens
Strengths
Fugu Ultra v2 is the higher-performance tier of Sakana AI's Fugu system, orchestrating stronger specialist agents than Fugu Max for the hardest reasoning and engineering tasks.
A router model decomposes each task, dispatches parts to specialist agents, and merges the results — an architecture aimed at problems that benefit from several perspectives.
Handles up to 1,000,000 input tokens and returns up to 128,000 output tokens per call, so whole codebases and long agent histories fit in one request.
Supports function calling, JSON schema structured outputs, reasoning effort control, and built-in web search options.
Quick start
Copy this snippet and start making calls with Fugu Ultra v2.
const res = await fetch('https://api.yepapi.com/v1/ai/chat', {
method: 'POST',
headers: {
'x-api-key': 'YOUR_API_KEY',
'Content-Type': 'application/json',
},
body: JSON.stringify({
"model": "sakana/fugu-ultra-v2",
"messages": [
{
"role": "user",
"content": "Explain API gateways in 2 sentences."
}
],
"maxTokens": 256
}),
});
const { data } = await res.json();
console.log(data.message.content);Why use Fugu Ultra v2 through YepAPI?
Fugu Ultra v2 API — pricing, context window & access
Fugu Ultra v2 is the higher-performance model in Sakana AI's Fugu family and the current revision of Fugu Ultra. Fugu is a learned multi-agent orchestration system: a language model trained to route parts of a task to specialist agents and combine their answers. Ultra v2 pairs stronger agents with a 1,000,000-token context window and up to 128,000 output tokens per response.
Through YepAPI you call Fugu Ultra v2 on an OpenAI-compatible endpoint with a single key — the same key that reaches GPT-6, Claude, Gemini and the SEO, SERP and scraping APIs.
What is Fugu Ultra v2?
Fugu Ultra v2 is Sakana AI's flagship Fugu tier. Where Fugu Max optimises for cost, Ultra v2 orchestrates the strongest specialist models in the system, so multi-step reasoning, code generation and research synthesis come back with more depth per call. It supersedes the original Fugu Ultra, which remains available upstream. The 128K output ceiling lets it return complete implementations or long reports in one response.
Build with Fugu Ultra v2 via YepAPI
YepAPI serves Fugu Ultra v2 on the OpenAI-compatible /v1/ai/chat endpoint. Point your base URL at YepAPI, add your key, and set the model string to fugu-ultra (or sakana/fugu-ultra-v2). Function calling, structured outputs and reasoning effort pass through unchanged. Dropping to Fugu Max for routine steps is a one-string change per request.
Fugu Ultra v2 API pricing — $7.00 / 1M input, $42.00 / 1M output
Fugu Ultra v2 costs $7.00 per 1M input tokens and $42.00 per 1M output tokens through YepAPI, pay per token with no minimums. That is the same price band as GPT-5.5, so treat it as a premium model: reserve it for tasks where the multi-agent depth pays for itself and route lighter work to Fugu Max.
Fugu Ultra v2 for hard reasoning and engineering
Ultra v2 suits problems that benefit from several angles of attack: architecture decisions, difficult debugging across a large codebase, research questions that need sources reconciled, and analyses where the reasoning must be shown. Built-in web search options ground its answers, and the 1M-token window keeps everything an agent has seen in context.
Try Fugu Ultra v2 free
Every new YepAPI account includes $5 in free credit with no card required — enough to put Fugu Ultra v2 through a few genuinely hard problems. Create an account, copy your key, and call fugu-ultra right away.
Start generating in 30 seconds
$5 free credit on signup. No credit card required. Pay per call.
What developers say
“Switched from SerpAPI and cut our SERP costs by 80%. Same data quality, way simpler billing.”
“One API key for AI models, SERP data, and web scraping. Saved us from managing 4 separate providers.”
“The $5 free credit let us prototype our entire rank tracking feature before committing. No other API does that.”
Frequently asked questions
Sakana AI's higher-performance Fugu model. A learned multi-agent orchestration system that routes work across stronger specialist models, with a 1M token context window and 128K output tokens.
Input tokens cost $7.00 per 1M tokens and output tokens cost $42.00 per 1M tokens through YepAPI. No monthly minimums — you only pay for what you use.
Sign up for a free API key, then send requests to the /v1/ai/chat endpoint.
Fugu Ultra v2 supports a 1M token context window with up to 128K output tokens per request.
Ready to use Fugu Ultra v2?
$5 free credit on signup. No credit card required. Pay per call.
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