First transfer on Cardano

• Keyan oda_… key: free with a wallet sign-in (300 calls), or bought with tADA. It goes in Authorization: Bearer.
• Walleta payment key for cardano-cli, or a browser wallet such as Lace, Eternl or Yoroi switched to preprod
• tADAfrom the Cardano testnet faucet. A few tADA cover the transfer and the fee.
• Toolscurl and jq, and cardano-cli for the shell example
• Costa handful of calls per transfer: build, submit and a status check every 15 seconds until it is confirmed. The key never pays the fee: that is tADA from your wallet.

shell# a payment key and its address
cardano-cli address key-gen \
  --verification-key-file payment.vkey \
  --signing-key-file payment.skey
cardano-cli address build \
  --payment-verification-key-file payment.vkey \
  --testnet-magic 1 > payment.addr

# your environment
ODATANO_KEY=oda_…
FROM=$(cat payment.addr)   # fund it first
TO=addr_test1…

• 1Build. BuildSimpleAdaTransaction selects the inputs, computes the fee and returns the unsigned transaction with its build id.
• 2Sign locally. Your key signs the transaction. It never leaves your machine.
• 3Submit. SubmitTransaction takes the build id and the signed transaction and returns the transaction hash.
• 4Confirm. CheckSubmissionStatus answers confirmed once the transaction is in a block, usually within a minute.

transfer.shAPI=https://api.preprod.odatano.dev
B=$API/odata/v4/cardano-transaction
H=(-H "Authorization: Bearer $ODATANO_KEY"
   -H 'Content-Type: application/json')

# 1 build: 2 tADA
jq -n --arg f "$FROM" --arg t "$TO" \
  '{senderAddress: $f, recipientAddress: $t,
    lovelaceAmount: 2000000}' > req.json
curl -s -X POST "$B/BuildSimpleAdaTransaction" \
  "${H[@]}" -d @req.json > build.json

# 2 sign locally
jq '{type: "Tx ConwayEra", description: "",
     cborHex: .unsignedTxCbor}' build.json > tx.json
cardano-cli conway transaction sign \
  --tx-file tx.json --signing-key-file payment.skey \
  --testnet-magic 1 --out-file tx.signed.json

# 3 submit
jq -n --arg b "$(jq -r .id build.json)" \
  --arg s "$(jq -r .cborHex tx.signed.json)" \
  '{buildId: $b, signedTxCbor: $s}' > submit.json
curl -s -X POST "$B/SubmitTransaction" \
  "${H[@]}" -d @submit.json > sub.json
jq '{id, txHash, status}' sub.json

# 4 confirm: repeat until "confirmed"
U="$B/TransactionSubmissions($(jq -r .id sub.json))"
curl -s -X POST "$U/CheckSubmissionStatus" \
  "${H[@]}" -d '{}' | jq .status

• Serveryour backend calls the API with the key. The key must never reach the browser, and the API takes no calls from browser pages of other sites.
• Browserthe user's wallet signs unsignedTxCbor through CIP-30 and returns a witness set
• Submitsend the witness set as signedTxCbor. SubmitTransaction adds it to the built transaction.
• Review stepCreateSigningRequest, VerifySignature and SubmitVerifiedTransaction check signer and body before anything is sent

browser// build came from your backend: { id, unsignedTxCbor }
const wallet = await window.cardano.lace.enable();
const witnessSet = await wallet.signTx(build.unsignedTxCbor, true);

// back to your backend, which calls
// SubmitTransaction { buildId: build.id, signedTxCbor: witnessSet }

• Readsblocks, transactions, UTxOs, addresses, pools, epochs and assets as OData under /odata/v4/cardano. A read is one call.
• Query$select, $filter, $expand, $top and $orderby work as in any OData service
• Explorerthe transaction hash from step 3 opens on preprod.cardanoscan.io
• Other buildsmetadata, native assets, minting and Plutus spends: the same build, sign and submit flow. See the reference.

httpGET https://api.preprod.odatano.dev/odata/v4/cardano/Transactions('<tx hash>')
GET https://api.preprod.odatano.dev/odata/v4/cardano/Addresses('<address>')
Authorization: Bearer oda_…