# Base64 Coding

## Overview

[`Base64`](/api/Base64) converts between Base64 strings and Ox's primitive types — the encoding
behind data URLs, HTTP payloads, and WebAuthn's transport format. Encoders exist for
[`Hex`](/api/Base64/fromHex), [`Bytes`](/api/Base64/fromBytes), and plain
[strings](/api/Base64/fromString), each with a matching decoder.

## Recipes

### Encode & Decode Data

Round-trip a value with [`Base64.fromString`](/api/Base64/fromString) and
[`Base64.toString`](/api/Base64/toString).

```ts twoslash
import { Base64 } from 'ox'

const encoded = Base64.fromString('hello world')
// @log: 'aGVsbG8gd29ybGQ='
const decoded = Base64.toString(encoded)
// @log: 'hello world'
```

[`Base64.fromBytes`](/api/Base64/fromBytes) and [`Base64.toBytes`](/api/Base64/toBytes) do the
same for `Uint8Array` payloads.

### Embed Calldata in URLs

Use [`Base64.fromHex`](/api/Base64/fromHex) with URL-safe characters to embed calldata or other
hex payloads in query strings, data URLs, and JSON APIs, then recover the hex with
[`Base64.toHex`](/api/Base64/toHex).

```ts twoslash
import { Base64 } from 'ox'

const encoded = Base64.fromHex('0xa9059cbb', { url: true, pad: false }) // [!code hl]
// @log: 'qQWcuw'
const calldata = Base64.toHex(encoded)
// @log: '0xa9059cbb'
```

## Best Practices

### Use URL-Safe Base64 on the Wire

The standard Base64 alphabet contains `+` and `/`, which break query strings and path segments.
Pass `{ url: true }` whenever the encoded value travels inside a URL.

## See More

<Cards>
  <Card icon="lucide:binary" title="Base58 Coding" description="The alphabet behind Bitcoin, IPFS, and Solana identifiers." to="/guides/data/base58" />

  <Card icon="lucide:hash" title="Work with Bytes & Hex" description="The primitive types every codec converts to and from." to="/guides/data/bytes-hex" />
</Cards>