Currency Converter API

Fiat and crypto currency converter -- ECB rates for fiat, CoinGecko for crypto. Instant cross-rate lookup. Pay-per-call via x402 (USDC on Base L2) -- no API key, no signup, no rate-limit wall.

Part of the klymax402 marketplace -- 100 x402 micropayment APIs for AI agents, one wallet, USDC on Base.

Quickstart -- MCP

Add to your MCP client config (Claude Desktop, Cursor, ElizaOS, etc.):

{
  "mcpServers": {
    "currency-converter": {
      "url": "https://currency-converter.api.klymax402.com/mcp"
    }
  }
}

Quickstart -- HTTP (x402)

curl -X POST "https://currency-converter.api.klymax402.com/api/convert" \
  -H "Content-Type: application/json" \
  -d '{"amount":"1","from":"...","to":"..."}'
# -> 402 Payment Required, with an x402 payment challenge in the response body

Any x402-aware client (@x402/fetch, x402-agent-tools, ATXP) handles the 402 -> sign -> retry cycle automatically.

Tools

Tool	Method	Path	Price	Description
finance_convert_currency	POST	/api/convert	$0.003	Convert between fiat currencies and cryptocurrencies

finance_convert_currency

Use this when you need to convert between any currencies -- both fiat (USD, EUR, GBP, JPY) and crypto (BTC, ETH, SOL). Returns conversion result in JSON.

Parameters

Name	Type	Required	Description
amount	number	yes	Amount to convert
from	string	yes	Source currency code (e.g., USD, EUR, BTC, ETH)
to	string	yes	Target currency code (e.g., EUR, GBP, USD, BTC)

Returns

• convertedAmount -- the resulting amount in target currency
• exchangeRate -- the rate used for conversion
• from -- source currency code
• to -- target currency code
• amount -- original amount provided
• rateSource -- data source used (ECB for fiat, CoinGecko for crypto)
• timestamp -- when the rate was fetched

Example response:

{"convertedAmount":2815.40,"exchangeRate":0.9218,"from":"USD","to":"EUR","amount":3054.00,"rateSource":"ECB","timestamp":"2026-04-13T12:00:00Z"}

When to use: price conversions across fiat and crypto in a single call. Essential for international pricing, invoice generation, and portfolio valuation in local currency.

Not for: market data or charts (use finance_get_token_price), DeFi swap quotes (use dex_get_swap_quote), wallet balances (use wallet_get_portfolio).

Example agent prompts

• "Convert between any currencies -- both fiat (USD, EUR, GBP, JPY) and crypto (BTC, ETH, SOL)"

Payment

• Protocol: x402 -- HTTP-native pay-per-call, no signup, no API key
• Network: Base L2 (eip155:8453)
• Asset: USDC
• Facilitator: Coinbase CDP (primary), PayAI (fallback)

Part of klymax402

100 x402 micropayment APIs for AI agents -- one wallet, USDC on Base, zero signup.

• Catalog: https://klymax402.com/llms.txt
• Full API reference: https://klymax402.com/llms-full.txt
• Live stats: https://klymax402.com/stats

License

MIT