Skip to main content
In sandbox you fund wallets from the faucet. In live, funds come from actual money sources — cards, bank accounts, crypto wallets, or hosted on-ramp sessions. This guide covers the full spectrum.

​
Funding options at a glance

SourceBest forSettlement time
Card (Stripe, Adyen)Small amounts, immediate fundingInstant
Bank (US ACH)Large amounts, low fees1-3 business days
Bank (EU SEPA)Euro funding1-2 business days
Bank (LATAM Pix / SPEI)Brazilian / Mexican flowsMinutes
Crypto walletPre-existing stablecoinOn-chain confirmation (seconds-minutes)
Hosted on-ramp (Coinbase, Stripe, Crossmint)Consumer-facing signup-to-fundedVariable

​
Step 1 — Register a funding source

curl -X POST https://api.getsly.ai/v1/funding/sources \
  -H "Authorization: Bearer pk_live_..." \
  -d '{
    "account_id": "acc_...",
    "type": "bank_account_us",
    "provider": "plaid",
    "public_token": "public-sandbox-abc123"
  }'

​
Source types and required fields

typeproviderRequired conditional fields
cardstripe, adyensetup_token
bank_account_usplaid, stripepublic_token or link_id
bank_account_euplaid, stripepublic_token
bank_account_latambelvolink_id
crypto_walletcircle (custodial)wallet_address, network
Non-custodial crypto wallets don’t require registration — agents can send directly to their Sly wallet address.

​
Step 2 — Verify the source

Bank accounts typically require verification (micro-deposits or identity check): 
curl -X POST https://api.getsly.ai/v1/funding/sources/fsr_.../verify \
  -H "Authorization: Bearer pk_live_..."
For Plaid-linked banks, verification happens in the link flow. For manual bank entry, micro-deposits arrive in 1-2 business days; the user confirms the amounts in your UI, which submits back to this endpoint. Source status transitions: unverified → verified | blocked.

​
Step 3 — Initiate funding

Once verified: 
curl -X POST https://api.getsly.ai/v1/funding/transactions \
  -H "Authorization: Bearer pk_live_..." \
  -d '{
    "source_id": "fsr_...",
    "wallet_id": "wal_...",
    "amount_cents": 50000,
    "currency": "USD",
    "idempotency_key": "fund-2026-04-23-001"
  }'
Amount is in minor units (amount_cents) — 50000 = $500.00 USD. Avoid float precision issues. Response: 
{
  "id": "fx_...",
  "status": "pending",
  "source_id": "fsr_...",
  "wallet_id": "wal_...",
  "amount_cents": 50000,
  "currency": "USD",
  "estimated_settlement": "2026-04-26T00:00:00Z",
  "fees": { "provider": 125, "sly": 0, "total": 125 }
}

​
Step 4 — Watch settlement

curl https://api.getsly.ai/v1/funding/transactions/fx_... \
  -H "Authorization: Bearer pk_live_..."
Status: pending → processing → completed | failed. Or subscribe to funding.transaction.completed webhook.

​
Hosted on-ramp (consumer-facing)

For consumer flows where the end-user completes funding in a branded Sly-hosted page — useful when you don’t want to build card/bank capture UI yourself.

​
Coinbase on-ramp (fiat → USDC → your wallet)

curl -X POST https://api.getsly.ai/v1/funding/onramp-session \
  -H "Authorization: Bearer pk_live_..." \
  -d '{
    "wallet_id": "wal_...",
    "default_amount_usd": 100,
    "supported_payment_methods": ["card", "ach"],
    "return_url": "https://yourapp.example/funded"
  }'
Returns { session_token, session_url }. Redirect the user; they complete funding in Coinbase’s flow; the wallet is credited on confirmation.

​
Stripe crypto on-ramp

Similar pattern, different provider: 
curl -X POST https://api.getsly.ai/v1/funding/stripe-onramp-session \
  -H "Authorization: Bearer pk_live_..." \
  -d '{
    "wallet_id": "wal_...",
    "default_amount_usd": 100
  }'

​
Crossmint order (card → USDC, web + mobile friendly)

curl -X POST https://api.getsly.ai/v1/funding/crossmint-order \
  -H "Authorization: Bearer pk_live_..." \
  -d '{
    "wallet_id": "wal_...",
    "amount_usd": 100,
    "return_url": "https://yourapp.example/funded"
  }'

​
Off-ramp (USDC → fiat)

The inverse — move from a Sly wallet out to a bank: 
curl -X POST https://api.getsly.ai/v1/funding/offramp-session \
  -H "Authorization: Bearer pk_live_..." \
  -d '{
    "wallet_id": "wal_...",
    "amount_usd": 500,
    "destination_bank_account_id": "bank_..."
  }'

​
Embedded widget session

For a Plaid / Belvo link flow embedded in your UI: 
curl -X POST https://api.getsly.ai/v1/funding/widget-sessions \
  -H "Authorization: Bearer pk_live_..." \
  -d '{
    "provider": "plaid",
    "account_id": "acc_...",
    "products": ["auth", "transactions"]
  }'
Returns a short-lived session token. Pass it to the Plaid Link SDK client-side.

​
Estimate fees before funding

curl -X POST https://api.getsly.ai/v1/funding/estimate-fees \
  -H "Authorization: Bearer pk_live_..." \
  -d '{
    "source_type": "card",
    "amount_cents": 50000,
    "currency": "USD",
    "destination_currency": "USDC"
  }'
Returns provider fee, Sly fee, FX spread, and total — useful for displaying to end users.

​
Cross-currency funding

Funding a USDC wallet from a USD bank account = on-ramp + FX. 
curl -X POST https://api.getsly.ai/v1/funding/conversion-quote \
  -H "Authorization: Bearer pk_live_..." \
  -d '{
    "from_currency": "USD",
    "to_currency": "USDC",
    "amount_cents": 50000
  }'
Use the returned quote_id on the funding transaction to lock in the rate.

​
List providers + supported pairs

curl https://api.getsly.ai/v1/funding/providers \
  -H "Authorization: Bearer pk_live_..."

curl https://api.getsly.ai/v1/funding/conversion-rates \
  -H "Authorization: Bearer pk_live_..."

​
Endpoints

EndpointPurpose
POST /v1/funding/sourcesRegister source
GET /v1/funding/sourcesList sources
POST /v1/funding/sources/:id/verifyTrigger verification
POST /v1/funding/transactionsInitiate funding
GET /v1/funding/transactions/:idTransaction status
POST /v1/funding/widget-sessionsPlaid/Belvo link session
POST /v1/funding/onramp-sessionCoinbase on-ramp
POST /v1/funding/stripe-onramp-sessionStripe on-ramp
POST /v1/funding/crossmint-orderCrossmint order
POST /v1/funding/offramp-sessionOff-ramp (USDC → fiat)
POST /v1/funding/estimate-feesFee preview
POST /v1/funding/conversion-quoteFX quote
GET /v1/funding/providersList providers
GET /v1/funding/conversion-ratesList supported currency pairs

​
Common pitfalls

  • Forgetting idempotency_key on funding transactions — retries create duplicate debits
  • Rounding in amount — always use amount_cents, never floats
  • Stale quotes — FX quotes expire in ~30 seconds; re-quote before large moves
  • Unverified source — sources in unverified state can’t fund; verify first
  • Provider-specific KYC — some providers require additional KYC beyond Sly’s; check the source’s verification_status