---
title: Send a Data Message
description: An IndexationPayload is a payload type that can be used to attach arbitrary data and a key index to a message.
image: /img/logo/iota_mark_light.png
keywords:
- how to
- key index
- data message
- arbitrary data
- client
- payloads
- java
- nodejs
- python
- wasm
- rust
---
import Tabs from "@theme/Tabs";
import TabItem from "@theme/TabItem";
import JavaDataMessage from "../libraries/java/examples/_08_data_message.mdx";
import NodejsGetDataMessage from "../libraries/nodejs/examples/_08_data_message.mdx";
import PythonGetDataMessage from "../libraries/python/examples/_08_data_message.mdx";
import RustGetDataMessage from "../libraries/rust/examples/_08_data_message.mdx";
import WasmGetDataMessage from "../libraries/wasm/examples/_08_data_message.mdx";

An [`IndexationPayload`](../explanations/messages_payloads_and_transactions.md#indexationpayload) is a payload type that can be used to attach arbitrary `data`
and a key `index` to a message. To send a payload, you should  at least provide the `index`. The data part
(as `bytes[]`) is optional.


<Tabs groupId="language">
  <TabItem value="java" label="Java">
    <JavaDataMessage />
  </TabItem>
  <TabItem value="nodejs" label="Nodejs">
    <NodejsGetDataMessage />
  </TabItem>
  <TabItem value="python" label="Python">
    <PythonGetDataMessage />
  </TabItem>
  <TabItem value="rust" label="Rust">
    <RustGetDataMessage />
  </TabItem>
  <TabItem value="wasm" label="Wasm">
    <WasmGetDataMessage />
  </TabItem>
</Tabs>


- You can find the message using its `message ID` in the
  [Tangle explorer](https://explorer.iota.org/devnet/message/8d4fa37be3c00691131c2c3e03e7b8b956c9118a2ce4be3a8597d51d82ed2de9).
- There are three prepared [payloads](../explanations/messages_payloads_and_transactions.md#corepayloads)(`transaction`, `milestone`, and `indexation`). However, at the time, the `indexation`
  payload is the only one in use.
- `data` contains arbitrary data encoded in bytes.
- Please note there is no IOTA address involved while sending data messages. Data messages are referenced using their
  `message ID` or `index` key.
- IOTA addresses are part of the `UTXO` data structure that is sent using the [`SignedTransaction`](./../explanations/messages_payloads_and_transactions#signedtransaction)
  payload.