Build-tx Flow

How non-custodial transaction building works under /v1/tx/*.

Aura is non-custodial — the API never holds private keys. Endpoints under /v1/tx/* return an unsigned transaction that the caller must sign with its own wallet (passkey, mobile wallet, hardware wallet, etc.) and submit to an Alephium node.

Anatomy of a build-tx response

Every /v1/tx/* endpoint returns the same shape:

{
  "unsignedTx":         "00010001...",
  "txId":               "abc123...",
  "fromGroup":          0,
  "toGroup":            0,
  "gasAmount":          20000,
  "gasPrice":           "100000000000",
  "collateralRequired": "666250000000000000",
  "attoAlphAmount":     "1000000000000000",
  "tokens": [
    { "id": "<usdt-id>", "amount": "666250000000000000" }
  ]
}

Field	Description
unsignedTx	Hex-encoded unsigned transaction. Pass directly to your wallet’s signUnsignedTx helper.
txId	The txId your wallet should produce after signing. Useful for client-side optimistic UI.
fromGroup / toGroup	Alephium shard groups.
gasAmount, gasPrice	Gas estimate for the transaction.
collateralRequired	USDT (or other token) that will be locked by the tx — useful for pre-flight balance checks.
attoAlphAmount	ALPH locked by the tx (covers gas + on-chain deposits; auto-swapped from USDT in most cases).
tokens[]	Tokens locked by the tx, with raw amounts.

End-to-end example: place a limit order

1. Build the unsigned tx

   curl -X POST https://api.aurabets.io/v1/tx/markets/<market-address>/orders \
     -H 'authorization: Bearer aura_live_xxx' \
     -H 'content-type: application/json' \
     -d '{
       "signerAddress":   "1Cef...",
       "signerPublicKey": "0233...",
       "side":            "buy",
       "outcome":         "yes",
       "price":           650,
       "quantity":        "1000000000000000000"
     }'
   
2. Sign with your wallet

   @alephium/web3

   import { web3 } from '@alephium/web3'
   
   const signed = await wallet.signUnsignedTx({
     signerAddress,
     unsignedTx: response.unsignedTx,
   })
   
3. Submit to any Alephium node

   const submitted = await nodeProvider.transactions.postTransactionsSubmit({
     unsignedTx: response.unsignedTx,
     signature:  signed.signature,
   })
   
   console.assert(submitted.txId === response.txId)
   

   Most wallets bundle the sign + submit step into a single signAndSubmitUnsignedTx helper.

Why this pattern?

Custodial API	Aura API
You hand over your key (or sign in to a custodian).	Your wallet signs locally; the API only constructs the tx.
Custodian can freeze, censor, or drain.	Aura cannot move your funds — at all.
Single point of failure.	Aura can go down without affecting your wallet.

This pattern is identical to how Polymarket, Hyperliquid, and other non-custodial trading platforms expose their write paths.

Build-tx endpoints (by domain)

Domain	Endpoint prefix
Orders	POST /v1/tx/markets/{address}/orders
Order cancel	DELETE /v1/tx/markets/{address}/orders/{id}
Vault	POST /v1/tx/vault/{deposit,unlock,withdraw}
Oracle	POST /v1/tx/oracle/{submit,dispute,commit,reveal}
Voting	POST /v1/tx/voting/vote
Proposals	POST /v1/tx/proposals/{single,linked,parlay}

See the API Reference → Endpoints tab for the full request/response schema of each.