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

Install in 30 seconds

Add this to your MCP client config:

config.json

{
  "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).

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

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.

Routing Engine

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

Code

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)

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

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)

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

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.

server.ts

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

server.ts

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())

Tech Stack

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

Project Structure

Code

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:

Terminal

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.

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.

Crossfin README