Product overview
Sakana AI Fugu: the model family, the API, and how billing works
Sakana AI Fugu is one name for four differently-behaving models behind a single OpenAI-compatible API. This page is the orientation: who made it, what each model is for, how to connect, what it costs, and where the official rules stop.
1. Sakana AI is the lab; Fugu is the product
Before any code, clear the naming. Sakana AI is the organization that built the family. Fugu is the product line: a multi-agent model family exposed through a developer console and an API. Official copy describes Fugu as coordinating a pool of models through one interface and learning collaboration patterns instead of using a hand-written workflow.
| Name | What it refers to | Practical meaning |
|---|---|---|
| Sakana AI | The lab and vendor | Owns the product page, the console, and the terms |
| Sakana Fugu | The model family | The product you call through the API |
| console.sakana.ai | The developer platform | Where Models and Pricing documentation and keys live |
fugu / fugu-ultra / fugu-max / fugu-cyber | Model IDs | The strings you send in a request |
That distinction matters because Sakana AI sells more than Fugu. The same pricing page documents sakana-namazu, a separate Japanese-specialized model with its own rates. Do not fold Namazu numbers into a Fugu estimate.
2. Four models, different operating rules
The API surface is shared, but each model has a different purpose, routing behavior, cost shape, and access requirement. Model choice is configuration, not a quality dial.
| Model ID | Use it for | Key constraint |
|---|---|---|
fugu | Interactive coding, chat, normal reviews, first evaluation pass | Pay-as-you-go cost varies with the routed model; pool opt-outs are allowed |
fugu-ultra | Difficult multi-step reasoning where quality is worth time and cost | Fixed deep agent pool, no opt-outs; published rates |
fugu-max | Cost-performance work where the bill matters as much as the answer | Fixed pool, no opt-outs; flat $2 / $6 / $0.25 per 1M tokens at any context |
fugu-cyber | Authorized defensive security reasoning and investigation | Pay-as-you-go only; returned only after access approval; sales-only pricing |
Ultra currently defaults to fugu-ultra-v2.0, with fugu-ultra-v1.1 and fugu-ultra-v1.0 (the former fugu-ultra-20260615) still documented. Fugu Max defaults to fugu-max-v1.0, and Cyber defaults to fugu-cyber-v1.0. Call GET /v1/models rather than assuming an alias is available to every key.
3. The API is OpenAI-compatible, not OpenAI-identical
Sakana AI supports three generation surfaces plus a models list. Compatibility describes the request envelope. It does not mean every field has the same effect.
| Surface | Path | Use it when |
|---|---|---|
| Responses | /v1/responses | New integrations; recommended for tools, multimodal, and reasoning controls |
| Chat Completions | /v1/chat/completions | An existing OpenAI chat client cannot move yet |
| Messages | /v1/messages | The caller is already an Anthropic Messages client |
| Models | /v1/models | Startup validation of IDs and access |
Two documented field rules save weeks of confusion. On Responses, temperature and parallel_tool_calls are accepted but ignored. On Chat Completions, top_p, stop, seed, the penalty fields, and temperature are accepted but ignored. previous_response_id is not accepted on Responses; send the full history in input. The full field list is on the API surfaces page.
4. Billing has a fixed part and a variable part
Ultra and Max have published per-million-token rates. Fugu is route-dependent. Cyber no longer has a public table. Subscriptions exist beside pay-as-you-go, and orchestration tokens are extra billable usage.
| Model and context | Input | Output | Cached input |
|---|---|---|---|
| Fugu Ultra (v2.0), up to 272K context | $5.00 | $30.00 | $0.50 |
| Fugu Ultra (v2.0), over 272K context | $10.00 | $45.00 | $1.00 |
| Fugu Max (v1.0), any context | $2.00 | $6.00 | $0.25 |
| Fugu Cyber | Not published on September 28, 2026. Official pages say to contact sales after access is approved. | ||
Standard Fugu pay-as-you-go is billed by route: one active agent is charged at that underlying model's rate, and several agents are charged at one rate based on the highest-tier model involved. There is no honest public fixed Fugu rate. Fugu Max is the opposite case: flat published rates at any context. Subscriptions are $20 (Standard), $100 (Pro), and $200 (Max) per month, described as 1×, 10×, and 20× Standard usage, with no published exact token allowance. They cover the API platform only — the separate Sakana Chat product is free with its own limits. See pricing explained for the full method.
Ultra and Cyber report orchestration usage outside the ordinary request totals, billed at the corresponding category rate. Within both the ordinary and orchestration input totals, cached tokens are a subset: subtract each cached count before applying the full input rate, then bill cached tokens at the discounted rate. A log that stores only input_tokens and output_tokens loses the fields needed to reconcile both orchestration usage and caching.
5. Connect in six steps
- Create an API key in the Sakana console and store it in an environment variable, never in source.
- Set the base URL to the OpenAI-compatible endpoint and make sure it ends in
/v1. - Choose the model ID (
fugu,fugu-ultra,fugu-max, orfugu-cyber) before writing the request. - Call
GET /v1/modelswith the same key and base URL and confirm the ID is present. - Send the first request through the Responses API with a finite timeout and a small bounded retry count.
- Persist the complete usage object, including orchestration fields, for cost reconciliation.
A copyable client with startup validation and bounded retries is on the API quickstart. The order above is deliberate: a model that is missing from the list is a deployment error you should catch before paying for generation.
6. Availability and access have hard edges
- EU and EEA: official product copy says Fugu is not yet available there while Sakana AI works toward GDPR and EU-specific compliance. Treat it as a stop, not a timeout.
- Cyber: pay-as-you-go billing only, plus a reviewed access request describing the use case and verified contact information.
- Partners: the product page lists OpenRouter, Vercel, opencode, Creao, and Merge. A listing is not proof that rates, Cyber access, or training opt-outs travel with that door.
- Namazu:
sakana-namazuis a separate Japanese-specialized model on the same pricing page; keep its costs separate from Fugu.
Details are split across EU availability, Cyber access, and third-party access.
7. Choosing a model, summarized
Start with Fugu for routine work. Try Fugu Max when cost per result matters most and Ultra when peak quality does, then decide with a paired, blind comparison on your own tasks. Consider Cyber only for authorized defensive security work after access is granted. If you must name every worker in an audit log, none of the managed Fugu models will satisfy that requirement, because official FAQ says the routing map is not exposed — see Fugu versus self-managed orchestration.
The model chooser encodes region, routing visibility, and workload into one recommendation, and will return "unavailable" for an EU or EEA production region before it looks at the task.
Frequently asked questions
Is Sakana Fugu free?
The API is not free: there is no permanent free API tier, subscriptions start at $20 per month, and pay-as-you-go billing is available. Sakana Chat is a separate product that is free with its own usage limits. See pricing explained.
Can I use standard OpenAI SDKs?
Yes. Point the client at the Sakana base URL with /v1 and your key. Several OpenAI-shaped fields are accepted but ignored, so validate behavior rather than assuming identical semantics.
Which model should I start with?
Fugu for interactive coding and reviews. Try Fugu Max when cost per result matters and Ultra when peak quality does, then decide with a blind comparison on your own hard tasks. Cyber is for authorized defensive security after access approval.
Where does Sakana AI end and Fugu begin?
Sakana AI is the lab and vendor; Fugu is the model family. The console at console.sakana.ai is the platform. A fuller separation is on the Sakana AI page.
Sources and verification boundary
- Sakana AI Fugu product page: model positioning, pool behavior, availability, and partner listing
- Sakana AI Models documentation: IDs, endpoints, supported fields, and usage details
- Sakana AI Pricing documentation: billing modes, Ultra and Max rates, and subscription tiers
Product facts are time sensitive and reflect the September 28, 2026 recheck. Re-read the official pages before a production decision in 2026 or later.