Real head-to-head · same prompt, one shot
Fugu Mini vs Claude Sonnet 5
Fugu's fast mini variant — single model, no panel, ~3 min per build. vs The agentic SWE frontier — 82% SWE-bench Verified, Dev Team mode.
Head-to-head verdict: Fugu Mini wins 17–16 with 3 ties.
What I tested — same prompt, two models
I run the same fixed prompt set through every new model the day it drops — same string, one shot, single HTML file out — and I score the result 0–10 on whether it ran, how close it hit the brief, and how good it looked. Below is what came out when I gave the exact same prompts to Fugu Mini and Claude Sonnet 5, side by side, on 37 shared tasks inside the Agent Operating System.
Both models were given identical prompts inside the Agent Operating System — no help, no iteration, no "best of N" tricks. I run each prompt once, save the HTML file the model produces, and score it 0–10 on whether it ran, how close it hit the brief, and how good it looked. The scoring is mine. The verdicts below are pulled from my source comparison guides at agentos.guide where I publish every score and the reasoning behind it.
Fugu Mini · Dispatched from Agent OS as the fast Sakana lane. Bench scored by Claude judge against the same 42 prompts.
Claude Sonnet 5 · Reach for it in Agent OS when the job is iterative, tool-using software engineering. For one-shot visual builds, GLM 5.2 (free) beat it 4-1 here.
Side-by-side on 42 shared tasks
Click any cell to play that model's actual one-shot attempt. Medals are derived from my 0–10 scores per task (highest = 🥇, second = 🥈, third = 🥉).
Task ↓
Fugu Mini
Claude Sonnet 5
Game
Game
Game
Game
Game
Game
Game
Game
Game
Game
Game
Game
Game
Game
Page
Page
Sim
Sim
Sim
Sim
Sim
Sim
Sim
Sim
Where Fugu Mini beat Claude Sonnet 5
The tasks where I gave Fugu Mini a higher 0–10 score on the same prompt — with the actual commentary from my source guides.
Solar
Sim
Fugu Mini 8.0
·
Claude Sonnet 5 2.5
(+5.5)
What I saw: Single-model Fugu Mini shipped a complete 12KB solar system in 3.5 min — full </html>, animation loop, Saturn rings, drag/orbit. Verified PASS by headless-Chrome smoke test (pixel-change + no console errors after click + WASD).
Wormhole
Sim
Fugu Mini 8.0
·
Claude Sonnet 5 3.0
(+5.0)
What I saw: 3D wormhole tunnel with distorted starfield. Smoke-test PASS.
Orbit
Sim
Fugu Mini 8.0
·
Claude Sonnet 5 3.5
(+4.5)
What I saw: Inner-system orbit map with hover info. Smoke-test PASS.
Aurora
Visual
Fugu Mini 6.5
·
Claude Sonnet 5 2.5
(+4.0)
What I saw: Aurora ribbons over mountain ridge. Smoke-test MAYBE-STATIC (<0.5% pixel diff after input) — animates but doesn't respond to keys (which is expected for this visual-only prompt).
Blackhole
Sim
Fugu Mini 8.0
·
Claude Sonnet 5 5.0
(+3.0)
What I saw: Gravitational-lensing black hole. Smoke-test PASS — pixel change confirmed after camera-orbit input.
Where Claude Sonnet 5 beat Fugu Mini
The tasks where I gave Claude Sonnet 5 a higher 0–10 score on the same prompt — with the actual commentary from my source guides.
Galaxy
Sim
Claude Sonnet 5 8.6
·
Fugu Mini 6.5
(+2.1)
· gorgeous spiral swirl
What I saw: Beautiful multi-arm spiral with convincing color gradient (warm core to violet edges), bright glowing bulge, and background starfield—clearly on-brief and polished. Full swirl/orbit/zoom interactivity with a mouse-influence vortex on the particles makes this a task winner.
Webos
Page
Claude Sonnet 5 8.0
·
Fugu Mini 6.5
(+1.5)
What I saw: Renders a polished dark desktop with animated starfield bg, working dock, taskbar pills, mac-style window controls, drag/resize, and functional apps (Notes/Paint/Terminal/About visible). Strong and shippable but visually generic and only shows two overlapping windows—doesn't quit…
Raycaster
Game
Claude Sonnet 5 8.0
·
Fugu Mini 7.0
(+1.0)
What I saw: Strong, shippable 3D maze: clean rendered walls with lighting/shadows, checkerboard floor, working minimap with player+goal markers, and solid controls/UI. Uses real 3D geometry rather than classic raycasting and looks a bit flat/plain (colored walls without texture), keeping it …
Rpg
Game
Claude Sonnet 5 7.4
·
Fugu Mini 6.5
(+0.9)
What I saw: Clean render with a readable 3D top-down world—billboard player/slime sprites, HP bar, XP, inventory slots and clear controls all present and on-brief; but the scene feels sparse/empty with sprawling green fields, few obstacles and no visible combat action, keeping it solid-shipp…
Cloth
Sim
Claude Sonnet 5 7.8
·
Fugu Mini 7.0
(+0.8)
What I saw: Strong Verlet cloth with visible draping folds over the sphere, clean UI and controls, and nice lighting/vertex-color tint. Weakness: the drape reads a bit shroud-like/pointy and the sphere obstacle is fully hidden, so the 'draping over an object' silhouette is less convincing th…
Strengths & weaknesses I logged
Fugu Mini
Strengths
- Zero panel orchestration — much lower latency than Ultra
- Same Sakana subscription, no extra cost
- Doesn't time out on heavy game/3D prompts where Ultra stalls
Trade-offs
- Single model only — no ensemble verdict
- Newer than Ultra — less calibration / verification
Claude Sonnet 5
Strengths
- 82.1% SWE-bench Verified — first model past 80% on real GitHub-issue repair
- Dev Team multi-agent mode + 1M context for repo-level agentic work
- Precision on hard logic — won the raycaster the open-weight field kept botching
Trade-offs
- One-shot creative-visual builds trail GLM 5.2 here (lost 4 of 5) — no iteration to catch its own bugs
- A temporal-dead-zone bug blanked its N-body orbit sim on the first shot
Pricing & context — the spec sheet
| Spec | Fugu Mini | Claude Sonnet 5 |
|---|---|---|
| Vendor | Sakana AI | Anthropic |
| Context window | Single-model variant of Sakana's Fugu — no panel orchestration. Same API endpoint, much faster per call. | 1,000,000 tokens |
| Price | Same Sakana subscription pool as Fugu Ultra | $3 / $15 per M ($2/$10 intro) |
| Pricing detail | The non-Ultra `fugu` model on Sakana's API. Sakana describes it as 'Fast mini model optimized for low latency yet high quality responses.' Crucially: zero orchestration tokens per call (vs Ultra's panel of thousands). Returns in ~3 min instead of 6-15 min and doesn't time out on heavy prompts. | $3.00 input / $15.00 output per million tokens; introductory $2.00/$10.00 through 2026-08-31. |
| Release | 2026-06-15 | 2026-06-30 |
| Bench coverage | 36/37 scored · avg 7.75/10 | 42/42 scored · avg 7.18/10 |
The verdict — which should you pick?
Across 36 scored shared tasks, Fugu Mini averaged 7.75/10, beating Claude Sonnet 5's 7.23/10 by 0.52 points. Pick Fugu Mini when the build has to ship on the first prompt and you can afford the trade-offs in the comparison below.
If you only run one of these inside your stack, the head-to-head average above is the call. If you can run both, my honest play is to wire Fugu Mini and Claude Sonnet 5 both into the Agent Operating System and dispatch each from the kanban by task type — agent loops where latency matters more than panel consensus → Fugu Mini, agentic software engineering — write / run / test / fix loops on real repos → Claude Sonnet 5. That's the same setup I run for the 3,600+ founders inside the AI Profit Boardroom.
FAQ — Fugu Mini vs Claude Sonnet 5
Which is better, Fugu Mini or Claude Sonnet 5?
On Goldie Bench, Fugu Mini averages 7.75/10 across the shared tasks, with 2 gold, 5 silver, 3 bronze overall. Claude Sonnet 5 averages 7.23/10, with 3 gold, 3 silver, 3 bronze. Fugu Mini wins the head-to-head 17–16.
How much does Fugu Mini cost vs Claude Sonnet 5?
Fugu Mini: The non-Ultra `fugu` model on Sakana's API. Sakana describes it as 'Fast mini model optimized for low latency yet high quality responses.' Crucially: zero orchestration tokens per call (vs Ultra's panel of thousands). Returns in ~3 min instead of 6-15 min and doesn't time out on heavy prompts. Claude Sonnet 5: $3.00 input / $15.00 output per million tokens; introductory $2.00/$10.00 through 2026-08-31.
What's the context window for Fugu Mini vs Claude Sonnet 5?
Fugu Mini has a Single-model variant of Sakana's Fugu — no panel orchestration. Same API endpoint, much faster per call. context window. Claude Sonnet 5 has a 1,000,000 tokens context window.
When should I pick Fugu Mini over Claude Sonnet 5?
Pick Fugu Mini for: Agent loops where latency matters more than panel consensus; Quick first-drafts you'll refine downstream; Filling out a bench when Ultra is timing out. The trade-off is the weaknesses we logged on the bench: Single model only — no ensemble verdict; Newer than Ultra — less calibration / verification.
When should I pick Claude Sonnet 5 over Fugu Mini?
Pick Claude Sonnet 5 for: Agentic software engineering — write / run / test / fix loops on real repos; Repo-level reasoning across a 1M-token context (Dev Team multi-agent mode); Precise logic — raycasters, physics — where one-shot open models slip. The trade-off is the weaknesses we logged on the bench: One-shot creative-visual builds trail GLM 5.2 here (lost 4 of 5) — no iteration to catch its own bugs; A temporal-dead-zone bug blanked its N-body orbit sim on the first shot.
How does Goldie Bench score Fugu Mini vs Claude Sonnet 5?
Every demo on this page was built by Julian Goldie inside the Agent Operating System — same fixed prompt for both models, one shot, single HTML file out. Each result gets a 0–10 score on whether it ran, how close it hit the brief, and how good it looked. The highest score on each task gets gold; second gets silver; third gets bronze. See methodology for full provenance.
Related comparisons
Other head-to-heads using the same scoring system:
Fugu Mini vs Fusion Claude Sonnet 5 vs Fusion Fugu Mini vs Hermes MoA Claude Sonnet 5 vs Hermes MoA Fugu Mini vs Grok Claude Sonnet 5 vs Grok Fugu Mini vs MiniMax M3 Claude Sonnet 5 vs MiniMax M3Full model pages: Fugu Mini · Claude Sonnet 5 · back to the leaderboard
The same stack Julian uses
Run this stack yourself.
Every demo on this bench was built inside the Agent Operating System — one prompt, one shot, single HTML file out. The Agent OS, the prompts, the templates, the weekly walkthroughs and 3,600+ founders shipping with it every day all live inside the AI Profit Boardroom.
3,600+founders
258documented wins
38countries
$59/momonthly