Stablecoins with Circle and Yellow Card
Connect your own Circle and Yellow Card accounts to see stablecoin balances, rates and payments, match them to your books and keep every money-moving action under your control.
Updated 11/10/2026
On this page
Stablecoins are digital dollars and euros (for example USDC and EURC) that move between businesses in minutes. Nexra connects to two providers in the Stablecoins & digital dollars category:
Circle: your Circle Mint account. See USDC and EURC balances, on-chain transfers, bank deposits and payouts, payments you received and conversion rates.
Yellow Card: your Yellow Card business account. See stablecoin and local-currency balances, rates, payment channels, payouts, collections, stablecoin sends, conversions and vault transactions.
With either one you can, without code, read what happened, show the rate on every transaction and match every payment, payout and fee to your ERP or ledger. Everything that reads is ready to use. Anything that would move money is switched off until your workspace decides otherwise, and even then a person approves every payment.
What you need
| Provider | Account | Credentials |
|---|---|---|
| Circle | A Circle Mint business account | An API key from Developer → API Keys in the Mint console |
| Yellow Card | A Yellow Card business (partner) account with Treasury Portal access | An API key and its secret from API Keys in the Treasury Portal |
Nexra never uses its own provider keys. You bring your own, they are stored encrypted, and you can rotate or remove them at any time. See Connections.
Start in the sandbox, then go live
Both providers offer a free sandbox where no real money moves. Always start there.
Circle
Sign in to the Circle Mint sandbox console at app-sandbox.circle.com (create a free sandbox account if you have none).
Open Developer → API Keys, choose Create an API key and name it, for example, Nexra.
In Nexra, open Connect → Connections, add Circle and paste the whole key, including the part before the first colon. Sandbox keys start TEST_API_KEY:.
Test the connection, then build and run your flows against it.
When you are ready, create a key in your live Circle Mint console (app.circle.com) and enter it when you take the flow live. Live keys start LIVE_API_KEY:. Nexra recognises these prefixes and refuses a live key on a test connection, or a test key on a live one.
Yellow Card
Sign in to the Treasury Portal with the invitation Yellow Card sent you.
Open API Keys and choose Create New. Tick API read. Tick API write only if your flows will send payouts or you want Nexra to register event triggers for you.
In Nexra, add Yellow Card and paste the API key and its secret. The secret is shown once in the portal.
Test the connection and build your flows against the sandbox.
Create production keys in the Treasury Portal and enter them when you take the flow live.
Live connections follow the usual go-live steps: a tested version, a second person's approval and a live check. See Approvals and deployments.
What is read-only
Every read action is available straight away and changes nothing at the provider.
| Circle | Yellow Card |
|---|---|
| Balances (available and unsettled USDC and EURC) | Balances across fiat and stablecoin wallets |
| On-chain transfers, bank deposits, bank payouts and stablecoin payouts | Payouts and collections (also found by your own reference) |
| Payments received and payment intents | Stablecoin sends and vault stablecoin transactions |
| Exchange rates, currency conversions and conversion settlements | Exchange rates and conversions |
| Linked bank accounts, deposit addresses and verified recipient addresses | Payment channels, and the banks and mobile networks each country supports |
| Account configuration |
Use them in flows (for example, post yesterday's stablecoin payouts to Teams each morning) and in reconciliation to match stablecoin payments, payouts and fees to your ledger. Personal details such as bank account numbers, recipient names, phone numbers and identity documents are never returned.
Each connector page lists its exact actions: Circle and Yellow Card.
What needs the money-movement switches
These actions move real money, so they are the highest risk tier (R4) and are refused by default:
| Provider | Action | What it does |
|---|---|---|
| Circle | transfers.create | Send stablecoin on-chain |
| Circle | bank_payouts.create | Pay out to your own bank account |
| Circle | stablecoin_payouts.create | Pay a recipient in stablecoin |
| Circle | payment_refunds.create | Refund a stablecoin payment |
| Yellow Card | payouts.create | Send a payout |
| Yellow Card | crypto_payouts.create | Send stablecoin to a wallet |
They run only when money movement is switched on for your workspace and for that exact action, with rules your workspace sets: which accounts and currencies, limits per payment and per day, which recipients, and who approves. Each switch is proposed by the workspace owner and approved by a different owner or admin. Then, for every payment:
A person your workspace chose approves it, and never the person who asked for it. Larger or riskier payments can need two approvers.
A live payment needs a successful sandbox payment of the same action first.
Every payment has its own key, sent to the provider too, so it is never sent twice, even when a run is retried.
If the provider's answer is unclear, Nexra marks the payment as unknown and never retries it by itself; a person checks it.
Every request, approval and provider response is kept as tamper-evident evidence, and the payment is matched in reconciliation.
Turning money movement off is immediate and needs no second approval. Nexra Agent can only propose a payment; MCP clients, the gateway and API keys can never move money.
Circle's payment_intents.create (asking a customer to pay you in stablecoin) moves no money out, so it is an ordinary write: switch it on for the connection and it follows your workspace's approval policies like any other write.
Currency conversions (Circle FX trades, Yellow Card conversions), creating addresses, linking bank accounts and similar account changes are not offered.
Events from Yellow Card
Yellow Card signs the events it sends, and Nexra can start a flow from them. Add a trigger and Nexra registers it with Yellow Card for you (this needs API write on the key):
When a collection is completed, or fails
When a payout is completed, or fails
When a stablecoin deposit or send settles
For Circle, Nexra checks the dated lists (transfers, deposits, payouts, payments, payment intents and conversions) on a schedule you choose. See Flow triggers and inputs.
Good to know
Circle Mint bank payouts are redemptions to your own bank account. Payments you receive settle straight to your Circle balance.
Stablecoin payments have no card-style chargebacks, and Yellow Card publishes no dispute API.
Yellow Card payouts and collections read a date window; without one they cover the last 24 hours.
Products such as payment intents and stablecoin payouts are enabled by Circle for each account, and Yellow Card decides countries, channels and limits for each account. Live keys reach only what your account is approved for.
Next
Govern overview: risk tiers, policies and approvals.
Webhooks: the payment.initiated, payment.completed and payment.failed events once payments are switched on.