> ## Documentation Index
> Fetch the complete documentation index at: https://docs.hubra.app/llms.txt
> Use this file to discover all available pages before exploring further.

# POST /broadcast

> Submit a fully signed transaction. Default route is plain Solana RPC; Sanctum is opt-in for swap flows.

```http theme={null}
POST https://hubra.app/api/v1/broadcast
```

Submit a fully signed transaction. The default route is plain Solana RPC, which works for any signed transaction (Sanctum-built, Voltr-built, native). The chain does not care which builder produced the bytes.

Optional `route: "sanctum"` (with `sanctumKind` and `sanctum_order`) forwards to Sanctum's execute endpoint, which adds MEV protection and smarter retries. Use it when broadcasting transactions that came back from `/stake` or `/unstake` with `route: "sanctum"`.

<Info>
  `hubra_token` is **required** on every call. Without a matching token, the endpoint rejects the request with `403 forbidden`.
</Info>

***

## Request

```bash theme={null}
curl -X POST https://hubra.app/api/v1/broadcast \
  -H 'Content-Type: application/json' \
  -d '{
    "signed_tx":   "<base64 signed tx>",
    "hubra_token": "<token from /stake or /unstake response>"
  }'
```

| Field           | Type                                                           | Required    | Description                                                                                                                                                                                  |
| --------------- | -------------------------------------------------------------- | ----------- | -------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
| `signed_tx`     | `string`                                                       | yes         | Base64-encoded fully signed transaction.                                                                                                                                                     |
| `hubra_token`   | `string`                                                       | yes         | Token from the matching `/stake` or `/unstake` response. HMAC over the unsigned message bytes. Tokens expire \~2 minutes after issue.                                                        |
| `route`         | `"rpc" \| "sanctum"`                                           | optional    | Defaults to `"rpc"`. Use `"sanctum"` for Sanctum-routed swap flows.                                                                                                                          |
| `sanctumKind`   | `"token" \| "depositStake" \| "depositSol" \| "withdrawStake"` | conditional | Required when `route="sanctum"`. Pass through the value from the `/stake` or `/unstake` response.                                                                                            |
| `sanctum_order` | `object`                                                       | conditional | Required when `route="sanctum"`. Pass through the `sanctum_order` object from the `/stake` or `/unstake` response. Sanctum's execute endpoint validates the signed transaction against this. |

***

## Response

```json theme={null}
{
  "signature": "5z6Z...",
  "explorer":  "https://solscan.io/tx/5z6Z..."
}
```

| Field       | Type     | Description                               |
| ----------- | -------- | ----------------------------------------- |
| `signature` | `string` | Base58 on-chain transaction signature.    |
| `explorer`  | `string` | Pre-built Solscan link for the signature. |

***

## When to use Sanctum routing

| You came from                          | Use                |
| -------------------------------------- | ------------------ |
| `/stake sol-liquid-stake`              | `route: "sanctum"` |
| `/stake sol-native-stake`              | `route: "rpc"`     |
| `/stake usdc-earn`                     | `route: "rpc"`     |
| `/unstake sol-native-stake instant`    | `route: "sanctum"` |
| `/unstake sol-native-stake deactivate` | `route: "rpc"`     |
| `/unstake sol-liquid-stake instant`    | `route: "sanctum"` |
| `/unstake sol-liquid-stake slow`       | `route: "sanctum"` |
| `/unstake usdc-earn instant`           | `route: "rpc"`     |
| `/withdraw`                            | `route: "rpc"`     |

The simple rule: if the build response had `route: "sanctum"`, broadcast with `route: "sanctum"` and forward the Sanctum-specific fields.

Sanctum's broadcaster adds MEV protection and smarter retries. Plain RPC works for any signed transaction; the chain itself does not distinguish.

***

## Signing example (Node + `@solana/web3.js`)

```ts theme={null}
import { VersionedTransaction, Keypair } from "@solana/web3.js";

// 1. Build the unsigned tx
const buildResp = await fetch("https://hubra.app/api/v1/stake", {
  method: "POST",
  headers: { "Content-Type": "application/json" },
  body: JSON.stringify({
    strategy: "sol-liquid-stake",
    wallet:   walletPubkey,
    amount:   "1.0",
  }),
}).then((r) => r.json());

const { transaction, hubra_token, route, sanctumKind, sanctum_order } = buildResp;

// 2. Sign locally
const tx = VersionedTransaction.deserialize(Buffer.from(transaction, "base64"));
tx.sign([wallet]); // wallet is a Keypair you hold
const signed = Buffer.from(tx.serialize()).toString("base64");

// 3. Broadcast — forward Sanctum-specific fields when applicable
const broadcastBody =
  route === "sanctum"
    ? { signed_tx: signed, hubra_token, route, sanctumKind, sanctum_order }
    : { signed_tx: signed, hubra_token };

const { signature } = await fetch("https://hubra.app/api/v1/broadcast", {
  method: "POST",
  headers: { "Content-Type": "application/json" },
  body: JSON.stringify(broadcastBody),
}).then((r) => r.json());

console.log(`Confirmed: https://solscan.io/tx/${signature}`);
```

For `sol-native-stake`, `tx.sign([wallet])` only fills the wallet's slot. The stake-account slot is pre-signed by Hubra's server.

***

## Errors

| Status | Slug              | When                                                                                                                                  |
| ------ | ----------------- | ------------------------------------------------------------------------------------------------------------------------------------- |
| `400`  | `invalid_request` | Missing `signed_tx`, missing `hubra_token`, missing `sanctum_order` (when `route="sanctum"`), or invalid `route` / `sanctumKind`.     |
| `403`  | `forbidden`       | `hubra_token` does not match this transaction, is malformed, or has expired. Rebuild via `/stake` or `/unstake` to get a fresh token. |
| `502`  | `upstream_error`  | RPC or Sanctum rejected the broadcast (invalid blockhash, signature failure, simulation failure, insufficient funds).                 |

***

## See also

<CardGroup cols={2}>
  <Card title="Hubra token" icon="lock" href="/developer/hubra-token">
    The HMAC mechanism in detail.
  </Card>

  <Card title="POST /stake" icon="key" href="/developer/endpoints/stake">
    Build a stake transaction.
  </Card>

  <Card title="POST /unstake" icon="rotate-left" href="/developer/endpoints/unstake">
    Build an unstake transaction.
  </Card>

  <Card title="Errors" icon="circle-exclamation" href="/developer/errors">
    Problem-details and slugs.
  </Card>
</CardGroup>