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Estimate fee

Returns gas-price and gas-limit estimates for a hypothetical transaction without submitting it. Useful for UI previews and pre-flight policy checks. 
GET /v1/transactions/estimate-fee?wallet_id={id}&to={addr}&value={wei}&data={hex}

curl "https://api.qustody.io/v1/transactions/estimate-fee?wallet_id=wal_01HXYZ&to=0xabc...&value=1000000000000000000" \
  -H "Authorization: Bearer $QUSTODY_API_KEY"
Response 200 
{
  "gas_limit": "21000",
  "gas_price_wei": "1000000000",
  "max_fee_per_gas_wei": "2000000000",
  "max_priority_fee_per_gas_wei": "1500000000",
  "estimated_fee_wei": "31500000000000",
  "chain_id": 20803,
  "estimated_at": "2026-04-27T10:15:00Z"
}
This call talks to the configured CUSTODY_NODE_RPC_URL. If the node is unavailable, the response is 1500 NODE_UNAVAILABLE. The estimate does not reserve a nonce or commit to broadcast.

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Export transactions

Streams a CSV (or JSON) of transactions matching the filter, suitable for accounting reconciliation. 
GET /v1/transactions/export?format=csv&from=2026-04-01T00:00:00Z&to=2026-04-30T23:59:59Z&status=CONFIRMED
Filters
ParamDescription
formatcsv (default) or json
from / toRFC 3339 time range
vault_idLimit to a vault
wallet_idLimit to a wallet
statusOne of the 14 transaction states
CSV columns 
id,external_id,vault_id,wallet_id,to_address,value_wei,fee_wei,status,broadcast_tx_hash,block_number,confirmed_at,created_at
Response headers 
Content-Type: text/csv; charset=utf-8
Content-Disposition: attachment; filename="transactions-2026-04.csv"
X-Total-Count: 4823
For large exports the response is streamed; clients should not buffer the entire body in memory.

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Required permissions

EndpointPermission
GET /v1/transactions/estimate-feetransactions:read
GET /v1/transactions/exporttransactions:export
The transactions:export action is a separate permission to allow segregation: a viewer can read individual transactions but a compliance_officer is typically the principal that exports.