# Work with RLP

## Overview

Recursive Length Prefix (RLP) is the Ethereum protocol's core serialization method — a
space-efficient standard for packaging and transferring arbitrarily nested byte data.
[`Rlp`](/api/Rlp) encodes and decodes it. RLP underpins
[transaction envelope serialization](/guides/transactions/build-sign-send),
[EIP-7702 authorization](/api/Authorization/getSignPayload) sign payloads, and
[`CREATE` contract address derivation](/api/ContractAddress/fromCreate).

## Recipes

### Encode & Decode a Value

Round-trip a single value with [`Rlp.fromHex`](/api/Rlp/fromHex) and
[`Rlp.toHex`](/api/Rlp/toHex).

```ts twoslash
import { Rlp } from 'ox'

const rlp = Rlp.fromHex('0x68656c6c6f')
// @log: '0x8568656c6c6f'
const value = Rlp.toHex(rlp)
// @log: '0x68656c6c6f'
```

### Encode Nested Data

[`Rlp.fromHex`](/api/Rlp/fromHex) serializes arbitrarily nested arrays of
[`Hex`](/api/Hex) values into a single RLP payload.

```ts twoslash
import { Hex, Rlp } from 'ox'

const rlp = Rlp.fromHex([
  Hex.fromString('hello'),
  Hex.fromNumber(1337),
  [Hex.fromString('foo'), Hex.fromString('bar')], // [!code hl]
])
// @log: '0xd28568656c6c6f820539c883666f6f83626172'
```

Working with `Uint8Array` data instead? [`Rlp.fromBytes`](/api/Rlp/fromBytes) accepts nested
[`Bytes`](/api/Bytes) and returns `Bytes`.

### Decode to Hex or Bytes

[`Rlp.toHex`](/api/Rlp/toHex) deserializes an RLP payload back into its original nested
structure with `Hex` leaves; [`Rlp.toBytes`](/api/Rlp/toBytes) does the same with `Bytes`
leaves.

```ts twoslash
import { Rlp } from 'ox'

const values = Rlp.toHex('0xd28568656c6c6f820539c883666f6f83626172')
// @log: ['0x68656c6c6f', '0x0539', ['0x666f6f', '0x626172']]
```

Either function accepts `Hex` or `Bytes` input, so raw payloads from the wire decode without a
manual conversion step.

## Best Practices

### Bring Your Own Schema

RLP encodes structure, not types. Decoding returns nested `Hex` (or `Bytes`) leaves — it is up
to you to reinterpret each position (`Hex.toString`, `Hex.toNumber`, …) according to the schema
the data was encoded with, in the same order.

## See More

<Cards>
  <Card icon="lucide:hash" title="Work with Bytes & Hex" description="Instantiate and convert the values RLP serializes." to="/guides/data/bytes-hex" />

  <Card icon="lucide:send" title="Build, Sign & Send" description="See RLP at work in transaction envelope serialization." to="/guides/transactions/build-sign-send" />

  <Card icon="lucide:signature" title="Delegate with EIP-7702" description="Sign over RLP-encoded authorization tuples." to="/guides/transactions/eip-7702" />
</Cards>