Solana Devnet

Trade the tails on-chain

Extreme-only prediction markets (90:10+) across 5 chains. Earn carry on the 90% side or swing for the tail — with multi-chain USDC, fiat on-ramp, bot API, and Telegram alerts.

Launch App Explore Markets

Which side are you?

THE CARRY

Stable Yield

Earn 5-15% APR by providing liquidity on the dominant side. Bond-like income from vig distribution.

Enter as Yield Seeker →

THE TAIL

Hunt Black Swans

10x+ returns on extreme events. Position sizing with Kelly criterion. Conviction rewarded.

Enter as Tail Hunter →

Why extreme-only?

No 50:50 noise — only heavily skewed markets

FatTail focuses on 90:10+ markets where probability is heavily skewed to one side. This creates a natural two-sided market: stable carry for the majority side, and explosive convexity for the tail.

90%

10%

vs 50 : 50

Extreme-only

Only markets with 90:10+ probability skew

Two-sided win

Carry for the 90% side, convexity for the tail

Scalable resolution

On-chain settlement + optimistic disputes

vs Others

What others don't do

FatTail is purpose-built for extreme probability markets. Here's how we compare.

Feature	FatTail	Polymarket	Kalshi
Probability Range	90:10+ only	Any range	Any range
Fee Model	Dynamic vig (0.3–3%)	Flat 2%	Flat 1%
Yield Mechanism	Vig distribution to 90% side	None	None
Bot API	REST + Python/TS SDKs	CLOB API	Limited
Settlement	Admin + Price Feed + Optimistic Oracle	UMA Oracle	Centralized

Two-sided value

Built for degens and market makers

Degens get tail convexity; MMs get structured carry with clear resolution rules.

Tail Convexity

Degens

Asymmetric payoff on low-probability events
10x+ returns when the unlikely hits
Black-swan positioning with real liquidity

Structured Carry

Market Makers

Insurance-like premium on the 90% side
Transparent resolution and dispute rules
Stable, bond-like yield from Vig distribution

How it works

Three steps to trade the tails

Pick a market

Browse extreme-probability events — crypto, macro, geopolitical.

Take a side

Go tail (10% side) for convexity, or carry (90% side) for yield.

Settle & collect

On-chain settlement. Objective markets auto-resolve; subjective markets use optimistic disputes.

Platform

Everything you need to trade the tails

Multi-chain, multi-wallet, real-time alerts — built for serious tail traders.

5-Chain Support

Trade on Solana, Base, Arbitrum, Optimism, and Polygon. Deposit and withdraw USDC across all chains.

Solana Base Arbitrum Optimism Polygon

K-Points + USDC

Trade with K-Points (regulatory-compliant) or connect a wallet for direct USDC trading.

Fiat On-ramp

Buy USDC with credit card or bank transfer via MoonPay. No crypto wallet required to start.

Wallet Connect

Phantom (Solana), MetaMask, Rabby, and more. Link your wallet for seamless USDC deposits.

Telegram Bot

Check balances, track positions, set price alerts, and receive push notifications — all from Telegram.

Dynamic Fees

Probability-weighted vig: ~0.6% for 90/10 markets, ~3% for 50/50. Lower fees where liquidity matters most.

Bot & API

Programmatic trading via REST API with API key auth. Python and TypeScript SDKs included. Build your own trading bot.

REST API Python SDK TypeScript SDK

Referral Program

Invite friends and earn bonus K-Points. Share your referral code — both you and your friend get rewarded.

Business Model

How FatTail generates value

A transparent fee structure that aligns platform growth with user returns.

Vig Flow

Every trade generates a dynamic fee (vig). 50% goes to the platform, 50% is distributed to yield seekers on the dominant side.

Trade

Vig (0.3–3%)

50% Platform

50% Yield Seekers

K-Point Mode

Regulatory-compliant point system. Users trade with K-Points — no direct cash exposure. Platform earns from vig on every trade.

USDC Mode

Direct crypto trading on 5 chains. USDC deposits, withdrawals, and settlement. Platform earns vig + potential spread.

Fiat On-ramp

MoonPay integration for card-to-USDC purchases. Platform earns referral commission on every fiat conversion.

Resolution

Three ways to settle

Every market has clear, pre-defined resolution rules.

Admin

Trusted resolution for early-stage markets by platform operators.

Price Feed

Automated settlement from on-chain price oracles (e.g., CoinGecko).

Optimistic Oracle

UMA-style propose → challenge → vote flow for subjective events.

Propose Challenge Vote Resolve

Read resolution rules

FAQ

Frequently asked questions

What is a 90:10 market?

A market where one outcome has at least 90% probability. FatTail exclusively hosts these heavily-skewed markets, creating natural two-sided value between carry seekers and tail bettors.

How does carry yield work?

When you take the 90% side, you earn carry from the vigorish (vig) — the spread embedded in every trade. Vig is distributed pro-rata to dominant-side holders, similar to an insurance premium.

What are K-Points?

K-Points (KP) are the platform's non-monetary point system used for trading. They allow participation without direct cash exposure, navigating regulatory requirements.

What is the Optimistic Oracle?

For subjective markets, anyone can propose a resolution. Others can challenge it by posting a bond. If challenged, token-weighted voting determines the outcome. The loser forfeits their bond.

What is LS-LMSR?

Liquidity Sensitive Logarithmic Market Scoring Rule — our automated market maker engine. The liquidity parameter scales with total volume, reducing slippage as more capital enters the market.

Which chains are supported?

Solana, Base, Arbitrum, Optimism, and Polygon. You can deposit and withdraw USDC on all five chains, or buy USDC with fiat via MoonPay.

How does the Telegram Bot work?

Link your Telegram account from the Portfolio page. Then use commands like /balance, /positions, and /markets to monitor your portfolio. Set price alerts with /alert and receive push notifications on trades and settlements.

What are the risks?

Smart contract risk, oracle risk, and market risk apply. Prices can move against you. Always read the resolution rules and risk disclosures before trading.

Can I build a trading bot?

Yes. Generate an API key from your account, then use our REST API or official Python/TypeScript SDKs to trade programmatically. The API supports market listing, trading, portfolio queries, and more.

How does the referral program work?

Share your unique referral code with friends. When they sign up and start trading, both you and your friend receive bonus K-Points. Check your referral stats on the Portfolio page.

Built with AI

Solo-built in weeks, not months

One builder + Claude Code = full-stack prediction market with 5-chain support, bot API, and Telegram integration.

15+

Phases

Unit Tests

45+

API Routes

Chains

Phase 1

Foundation — LS-LMSR math engine + 69 unit tests

Phase 2

DB & Auth — Supabase with RLS + K-Point system

Phase 3

Trading — Buy/sell with dynamic vig + safety guards

Phase 4

Oracle — Admin + Price Feed + Optimistic dispute resolution

Phase 5

Multi-chain — Solana + Base + Arbitrum + Optimism + Polygon

Phase 6

Telegram Bot — Balance, positions, price alerts via grammY

Phase 7

Bot API — REST API + Python/TypeScript SDKs for algorithmic trading

Phase 8

Landing + Docs — Astro 5 landing, Starlight docs, multi-subdomain deploy

AI as Core Building Partner

Claude Code wasn't just an autocomplete tool — it was the architect, debugger, and reviewer. Every phase was planned, implemented, tested, and documented through AI-assisted development, proving that a solo builder can ship production-grade DeFi infrastructure.

Ready to trade the tails?

Join the extreme-only prediction market — settled on-chain, multi-chain ready.

Launch App