The world's first coin was struck in Sardis, in Anatolia, 2,600 years ago. Sardium carries that legacy into the digital age: taking value at its source and moving it, safely.
Kingdom of Lydia, ~600 BC · where money was born
Non-custodial · we never touch your funds
Accept crypto payments, without touching the money.
Sardium is a white-label crypto checkout for merchants. Your customer pays by card or a local payment method through a licensed provider; the stablecoin lands in the customer's own self-custody wallet, and the customer signs and sends the payment to your wallet. No custody, no exchange account, no middleman to trust.
USDC / USDT
PolygonBaseArbitrumOptimism
How it works
Three steps. Funds never rest with us.
01
Customer pays by card
The payment widget embeds in your site. The customer pays by card or a local payment method in a familiar flow.
02
Licensed provider converts to crypto
Fiat processing and identity verification (KYC) are handled entirely by licensed payment providers. The stablecoin is delivered to the customer's own self-custody wallet.
03
The customer signs, you get paid
The customer signs the payment from their own wallet and sends it to your self-custody wallet. Sardium servers never access the funds.
Why Sardium
The weight of real infrastructure, the ease of a snippet.
Non-custodial
We hold funds at no stage. Only the user controls their wallet and holds its keys; our servers never hold private keys.
White-label
Your colour, your brand. The widget looks like part of your site.
Multi-chain
USDC and USDT across Polygon, Base, Arbitrum and Optimism.
Licensed providers
Identity verification (KYC) for the card purchase is run by the licensed payment provider, under its own licence.
Fast integration
One key, one snippet. A working payment flow in an afternoon, once your business is verified.
Transparent
Every transfer is verifiable on-chain and delivered via signed webhooks.
Built for
Built for businesses that sell across borders.
E-commerce
Card checkout for shoppers abroad, stablecoin in your own wallet.
Read more →Travel agencies
Bookings paid by card, with the money arriving in a wallet you control.
Read more →Online education
Students pay by card; a signed webhook tells your platform to open the course.
Read more →Import and export
Buyers abroad pay an invoice by card; you receive stablecoin in your own wallet.
Read more →Em português: E-commerce · Agências de viagem · Educação online · Importação e exportação
En español: E-commerce · Agencias de viaje · Educación online · Importación y exportación
Integration
As simple as an iframe.
Freeze the order on your server with your secret key and get a one-time token; your page embeds the widget with that token and your publishable key (pk_live_…). The amount and the recipient never pass through the browser. Full docs arrive with your access request.
// 1. your server: freeze the order with your secret key const r = await fetch('https://api.sardium.com/v1/checkout/intents', { method: 'POST', headers: { 'X-Api-Key': process.env.SARDIUM_SECRET_KEY, 'content-type': 'application/json' }, body: JSON.stringify({ chainId: 'polygon', tokenSymbol: 'USDC', amountRaw: '100000000', orderId: 'ORD-100' }) // 100 USDC, 6 decimals }); const { data } = await r.json(); // data.token: one use, valid 30 minutes <!-- 2. your page: the token names the order --> <iframe src="https://app.sardium.com/?intent=TOKEN_FROM_YOUR_SERVER &key=pk_live_YOURKEY" width="100%" height="640" style="border:0"> </iframe>
FAQ
Questions, answered honestly.
Who holds the funds?
No one in the middle. The card payment is processed by a licensed provider; the stablecoin lands in the customer's own self-custody wallet, and the customer signs and sends the payment to your self-custody wallet. Sardium holds neither fiat nor crypto at any stage.
Do I need an exchange account?
No. A self-custody wallet address on one of the supported chains is all you need.
Which chains and stablecoins are supported?
USDC and USDT on Polygon, Base, Arbitrum and Optimism.
Who performs identity verification (KYC)?
Identity verification and fiat processing are performed by licensed payment providers, under their own licences. Any obligations your own business has towards its customers stay with you.
How long does integration take?
The widget is an iframe: it embeds with the token of an order your server froze and your publishable key. Full documentation arrives with your access request.
Is Sardium live?
Yes. Sardium is live and used by businesses. Write to us and we'll guide you through business verification (KYB).
Bring crypto payments to your site.
Fill in the application form; we'll guide you through business verification (KYB).
Request access