CrossFin

The only way AI agents access Asian crypto markets.

CrossFin is a financial router for AI agents. It finds the cheapest path to move money across 14 exchanges (Bithumb, Upbit, Coinone, GoPax, bitFlyer, WazirX, bitbank, Indodax, Bitkub, Binance, OKX, Bybit, KuCoin, Coinbase), pays for APIs with crypto (x402 protocol), and gives agents real-time access to market data that's normally locked behind Korean-language interfaces and IP restrictions.

Live: crossfin.dev | Demo: live.crossfin.dev

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Install in 30 seconds

Add this to your MCP client config:

{
  "mcpServers": {
    "crossfin": {
      "command": "npx",
      "args": ["-y", "crossfin-mcp"],
      "env": {
        "EVM_PRIVATE_KEY": "0x..."
      }
    }
  }
}

Restart your MCP client. Done. 16 tools available immediately.

All API endpoints are currently free during open beta. No API key required. EVM wallet is optional (needed for x402 payment flow testing).

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What can it do?

Ask your agent:

• "빗썸에서 바이낸스로 500만원 USDC 만들려면 가장 싼 방법이 뭐야?" → Routing engine evaluates 13 bridge coins across 14 exchanges, returns optimal path with fees
• "지금 한국-글로벌 스프레드 얼마야?" → Real-time price spread between Korean and global exchanges for 13 crypto pairs
• "일본이랑 태국 프리미엄 비교해줘" → Asian Premium Index across Korea, Japan, Indonesia, Thailand
• "오늘 한국 시장 브리핑해줘" → Morning Brief bundle: route spread + FX + headlines

For developers/agents:

• find_optimal_route — cheapest/fastest/balanced path across Bithumb, Upbit, Coinone, GoPax, bitFlyer, WazirX, bitbank, Indodax, Bitkub, Binance, OKX, Bybit, KuCoin, Coinbase using 13 bridge coins (BTC, ETH, XRP, SOL, DOGE, ADA, DOT, LINK, AVAX, TRX, KAIA, SUI, APT)
• get_kimchi_premium — real-time Korean vs. global route spread
• compare_exchange_prices — live Bithumb KRW vs Binance USD price comparison
• call_paid_service — call any paid API with automatic x402 USDC payment (currently free during open beta)
• Asian Premium endpoints — Japan, Indonesia, Thailand crypto premiums vs global markets

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Why CrossFin?

Korean exchanges are a walled garden. Korean-language APIs, IP restrictions, real-name bank account requirements (실명확인 계좌제), and no English documentation. AI agents can't access them — unless they go through CrossFin.

Prices differ across exchanges. The same BTC can be 2-3% more expensive on Korean exchanges (route spread). CrossFin's routing engine finds the cheapest bridge coin and path, factoring in trading fees, withdrawal fees, slippage, and transfer time.

x402 ready. No API keys, no subscriptions, no invoices. All endpoints are currently free during open beta. x402 payment infrastructure (USDC on Base) ready for future activation.

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Routing Engine

The core product. Given a source (exchange + currency) and destination, CrossFin evaluates all possible paths:

Input:  bithumb:KRW → binance:USDC, ₩5,000,000
Output: Buy AVAX on Bithumb → Transfer to Binance → Sell for USDC
        Cost: 0.07% (₩3,500) | Time: ~3 min | Output: $3,452 USDC

        Alternatives:
        BTC  → 0.33% | ~21 min | $3,443
        DOT  → 0.38% | ~6 min  | $3,441

Considers: trading fees (0.10–0.25%), withdrawal fees (fixed per coin), orderbook slippage, transfer time, route spread direction.

Supports bidirectional routing: Korea → Global and Global → Korea.

Free preview: POST /api/acp/quote (ACP compatible) Full route: GET /api/premium/route/find (free during open beta)

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MCP Tools (16 total)

Tool	What it does
find_optimal_route	Optimal crypto transfer path across 14 exchanges (free)
list_exchange_fees	Trading + withdrawal fee comparison
compare_exchange_prices	Live Bithumb KRW vs Binance USD comparison
get_kimchi_premium	Korean vs. global route spread (free preview)
search_services	Search registered services
get_guide	Full agent guide (services, payment flow, examples)
call_paid_service	Call any paid API with automatic x402 payment
create_wallet	Local ledger wallet
get_balance	Check wallet balance
transfer	Transfer between wallets
list_transactions	Transaction history
set_budget	Daily spend limit
list_services	Browse service catalog
get_service	Service details
list_categories	Service categories
get_analytics	Gateway usage stats

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Asian Premium Index (v1.18.0)

Real-time crypto premium analysis across 4 Asian countries. All free, no API key needed.

Endpoint	Description
GET /api/premium/asia/japan	Japan premium — bitbank.cc JPY vs Binance USD
GET /api/premium/asia/indonesia	Indonesia premium — Indodax IDR vs Binance USD
GET /api/premium/asia/thailand	Thailand premium — Bitkub THB vs Binance USD
GET /api/premium/asia/overview	4-country overview (Korea + Japan + Indonesia + Thailand)

Data sources: bitbank.cc (Japan), Indodax (Indonesia), Bitkub (Thailand), Bithumb (Korea), Binance (Global)

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API Endpoints (Currently All Free)

All endpoints are currently free during open beta. x402 payment infrastructure is ready for future activation.

Korean Market APIs

Endpoint	Price	Description
/api/premium/arbitrage/kimchi	Free	Full Route Spread (13 pairs incl. KAIA, SUI, APT)
/api/premium/arbitrage/opportunities	Free	Arbitrage indicators (POSITIVE_SPREAD/NEUTRAL/NEGATIVE_SPREAD)
/api/premium/bithumb/orderbook?pair=BTC	Free	Bithumb orderbook (30 levels)
/api/premium/market/upbit/ticker	Free	Upbit ticker
/api/premium/market/upbit/orderbook	Free	Upbit orderbook
/api/premium/market/coinone/ticker	Free	Coinone ticker
/api/premium/market/fx/usdkrw	Free	USD/KRW exchange rate
/api/premium/market/korea	Free	Korean market sentiment
/api/premium/market/cross-exchange	Free	Cross-exchange arbitrage decision
/api/premium/news/korea/headlines	Free	Korean headlines
/api/premium/arbitrage/kimchi/history	Free	Route spread history (7 days)
/api/premium/bithumb/volume-analysis	Free	Bithumb volume analysis
/api/premium/market/upbit/signals	Free	Upbit trading signals
/api/premium/crypto/korea/5exchange	Free	Cross-exchange price comparison
/api/premium/crypto/korea/exchange-status	Free	Deposit/withdrawal status
/api/premium/crypto/korea/fx-rate	Free	Real-time KRW/USD (Upbit CRIX)
/api/premium/crypto/korea/upbit-candles	Free	Upbit OHLCV candles

Bundle APIs

Endpoint	Price	Description
/api/premium/morning/brief	Free	Morning Brief (route spread + FX + headlines)
/api/premium/crypto/snapshot	Free	Crypto Snapshot (4-exchange + route spread + volume + FX)
/api/premium/kimchi/stats	Free	Route Spread Stats (spreads + trend + arbitrage signal)

Utility APIs (Temporarily Free in Open Beta)

Endpoint	Price	Description
/api/premium/report	Free	Premium report (agents/wallets/transactions summary)
/api/premium/enterprise	Free	Enterprise receipt/proof endpoint
/api/legal/disclaimer	Free	Full legal disclaimer (EN/KO)
/api/analytics/overview	Free	Gateway analytics overview
/api/analytics/funnel/overview	Free	Funnel analytics overview
/api/analytics/funnel/events	Free	Funnel analytics event ingestion
/api/analytics/services/{serviceId}	Free	Per-service analytics
/api/onchain/usdc-transfers	Free	On-chain USDC transfer monitor (Base)
/api/proxy/{serviceId}	Free	Proxy endpoint for registered services
/api/telegram/webhook	Free	Telegram bot webhook endpoint

Protocol APIs (A2A + ACP)

Endpoint	Price	Description
POST /api/a2a/tasks	Free	A2A task execution (crypto-routing, route-spread, market data)
GET /api/acp/status	Free	ACP protocol status and capabilities
POST /api/acp/quote	Free	ACP-compatible routing quote (preview)
POST /api/acp/execute	Free	ACP execution endpoint

Routing Engine

Endpoint	Price	Description
GET /api/route/exchanges	Free	Supported exchanges and coins
GET /api/route/fees	Free	Fee comparison table
GET /api/route/pairs	Free	Trading pairs with live prices
GET /api/route/status	Free	Exchange health check
GET /api/premium/route/find	Free	Full optimal route analysis
POST /api/acp/quote	Free	ACP-compatible routing quote (preview)

Registry & Discovery (Free)

Endpoint	Description
GET /api/registry	List all registered services
GET /api/registry/search?q=...	Full-text search
GET /api/registry/categories	Categories with counts
GET /api/registry/stats	Registry stats (total/crossfin/external)
GET /api/docs/guide	Structured agent guide
GET /.well-known/crossfin.json	Agent auto-discovery
GET /.well-known/x402.json	x402 discovery metadata
GET /.well-known/agent.json	A2A Agent Card
GET /.well-known/ai-plugin.json	OpenAI plugin manifest
GET /llms.txt	LLM-readable site map
GET /api/openapi.json	OpenAPI 3.1 spec

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Payment (x402)

Note: All endpoints are currently free during open beta. The x402 payment code below is for reference when payments are re-enabled.

No API keys. No subscriptions. Pay per call with USDC on Base.

import { x402Client, wrapFetchWithPayment } from '@x402/fetch'
import { registerExactEvmScheme } from '@x402/evm/exact/client'
import { privateKeyToAccount } from 'viem/accounts'

const signer = privateKeyToAccount(process.env.EVM_PRIVATE_KEY)
const client = new x402Client()
registerExactEvmScheme(client, { signer })

const paidFetch = wrapFetchWithPayment(fetch, client)
const res = await paidFetch('https://crossfin.dev/api/premium/arbitrage/kimchi')
console.log(await res.json())

Python

import os
from eth_account import Account
from x402 import x402ClientSync
from x402.http.clients import x402_requests
from x402.mechanisms.evm import EthAccountSigner
from x402.mechanisms.evm.exact.register import register_exact_evm_client

client = x402ClientSync()
account = Account.from_key(os.environ['EVM_PRIVATE_KEY'])
register_exact_evm_client(client, EthAccountSigner(account))

with x402_requests(client) as session:
    r = session.get('https://crossfin.dev/api/premium/arbitrage/kimchi')
    print(r.json())

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Tech Stack

Cloudflare Workers + Hono, D1 (SQLite), x402 protocol, USDC on Base, MCP SDK, React + Vite (dashboard)

Project Structure

apps/
  api/          Cloudflare Workers API
  mcp-server/   MCP Server (16 tools, npm: crossfin-mcp)
  web/          Gateway Dashboard (crossfin.dev)
  live/         Live Demo (live.crossfin.dev)
  docs/         Documentation (docs.crossfin.dev)

Release Verification

Run a full pre-deploy verification sweep in one command:

npm --prefix apps/api run verify:release

This command runs API contract/catalog verification, builds API/web/docs in parallel, checks production API/page responses, and fails on stale copy patterns in README/docs/web/live/examples.

Links

• Dashboard — Gateway UI
• Live Demo — Real-time routing demo
• Agent Guide — Structured JSON for agents
• OpenAPI Spec — Machine-readable API spec
• Docs — Developer documentation
• npm: crossfin-mcp — MCP server package

Built with AI

CrossFin was built entirely through AI collaboration by a non-developer in 1 week. Zero prior coding experience. This project is proof that AI agents can build production software — and CrossFin is the infrastructure for that future.