# multiformats

> Interface for multihash, multicodec, multibase and CID

Latest version **14.0.5** (published 2026-07-23) · Apache-2.0 OR MIT license · 0 weekly downloads

## Install

```sh
npm install multiformats
pnpm add multiformats
yarn add multiformats
bun add multiformats
```

## Health

**Score 75/100 (B)** — status: active.

Positive: has types; esm support; no vulnerabilities; has provenance; recently updated; high maintenance score; high quality score.

Warnings: low downloads.

## Facts

| | |
|---|---|
| Version | 14.0.5 |
| Published | 2026-07-23 |
| First published | 2020-05-08 |
| Weekly downloads | 0 |
| License | Apache-2.0 OR MIT |
| TypeScript types | bundled |
| Module format | ESM |
| Dependencies | 0 |
| Unpacked size | 416.7 KB |
| Known vulnerabilities | 0 |
| Install scripts | no |
| Provenance | attested (GitHub Actions) |
| GitHub stars | 269 |
| Author | Mikeal Rogers |
| Maintainers | rvagg, npm-service-account-multiformats |
| Keywords | ipfs, ipld, multiformats |

## Links

- npm: https://www.npmjs.com/package/multiformats
- Repository: https://github.com/multiformats/js-multiformats
- Homepage: https://github.com/multiformats/js-multiformats#readme
- Issues: https://github.com/multiformats/js-multiformats/issues
- npm.io page: https://npm.io/package/multiformats

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## Recent versions

- 14.0.5 (latest) — 2026-07-23
- 10.0.0-pre.3 (next) — 2022-09-20
- 14.0.4 — 2026-07-03
- 14.0.3 — 2026-06-30
- 14.0.2 — 2026-06-24
- 14.0.1 — 2026-06-24
- 14.0.0 — 2026-05-07
- 13.4.2 — 2025-12-12
- 13.4.1 — 2025-09-15
- 13.4.0 — 2025-08-05
- 13.3.7 — 2025-06-10
- 13.3.6 — 2025-05-21
- 13.3.5 — 2025-05-20
- 13.3.4 — 2025-05-15
- 13.3.3 — 2025-05-08
- … 154 more at https://npm.io/package/multiformats/versions

## README

# multiformats

[![multiformats.io](https://img.shields.io/badge/project-IPFS-blue.svg?style=flat-square)](http://multiformats.io)
[![codecov](https://img.shields.io/codecov/c/github/multiformats/js-multiformats.svg?style=flat-square)](https://codecov.io/gh/multiformats/js-multiformats)
[![CI](https://img.shields.io/github/actions/workflow/status/multiformats/js-multiformats/js-test-and-release.yml?branch=master\&style=flat-square)](https://github.com/multiformats/js-multiformats/actions/workflows/js-test-and-release.yml?query=branch%3Amaster)

> Interface for multihash, multicodec, multibase and CID

# About

<!--

!IMPORTANT!

Everything in this README between "# About" and "# Install" is automatically
generated and will be overwritten the next time the doc generator is run.

To make changes to this section, please update the @packageDocumentation section
of src/index.js or src/index.ts

To experiment with formatting, please run "npm run docs" from the root of this
repo and examine the changes made.

-->

This library defines common interfaces and low level building blocks for various interrelated multiformat technologies (multicodec, multihash, multibase, and CID). They can be used to implement custom base encoders / decoders / codecs, codec encoders /decoders and multihash hashers that comply to the interface that layers above assume.

This library provides implementations for most basics and many others can be found in linked repositories.

```TypeScript
import { CID } from 'multiformats/cid'
import * as json from 'multiformats/codecs/json'
import { sha256 } from 'multiformats/hashes/sha2'

const bytes = json.encode({ hello: 'world' })

const hash = await sha256.digest(bytes)
const cid = CID.create(1, json.code, hash)
//> CID(bagaaierasords4njcts6vs7qvdjfcvgnume4hqohf65zsfguprqphs3icwea)
```

## Creating Blocks

```TypeScript
import * as Block from 'multiformats/block'
import * as codec from '@ipld/dag-cbor'
import { sha256 as hasher } from 'multiformats/hashes/sha2'

const value = { hello: 'world' }

// encode a block
let block = await Block.encode({ value, codec, hasher })

block.value // { hello: 'world' }
block.bytes // Uint8Array
block.cid   // CID() w/ sha2-256 hash address and dag-cbor codec

// you can also decode blocks from their binary state
block = await Block.decode({ bytes: block.bytes, codec, hasher })

// if you have the cid you can also verify the hash on decode
block = await Block.create({ bytes: block.bytes, cid: block.cid, codec, hasher })
```

## Multibase Encoders / Decoders / Codecs

CIDs can be serialized to string representation using multibase encoders that implement [`MultibaseEncoder`](https://github.com/multiformats/js-multiformats/blob/master/src/bases/interface.ts) interface. This library provides quite a few implementations that can be imported:

```TypeScript
import { base64 } from "multiformats/bases/base64"
cid.toString(base64.encoder)
//> 'mAYAEEiCTojlxqRTl6svwqNJRVM2jCcPBxy+7mRTUfGDzy2gViA'
```

Parsing CID string serialized CIDs requires multibase decoder that implements [`MultibaseDecoder`](https://github.com/multiformats/js-multiformats/blob/master/src/bases/interface.ts) interface. This library provides a decoder for every encoder it provides:

```TypeScript
CID.parse('mAYAEEiCTojlxqRTl6svwqNJRVM2jCcPBxy+7mRTUfGDzy2gViA', base64.decoder)
//> CID(bagaaierasords4njcts6vs7qvdjfcvgnume4hqohf65zsfguprqphs3icwea)
```

Dual of multibase encoder & decoder is defined as multibase codec and it exposes
them as `encoder` and `decoder` properties. For added convenience codecs also
implement `MultibaseEncoder` and `MultibaseDecoder` interfaces so they could be
used as either or both:

```TypeScript
cid.toString(base64)
CID.parse(cid.toString(base64), base64)
```

**Note:** CID implementation comes bundled with `base32` and `base58btc`
multibase codecs so that CIDs can be base serialized to (version specific)
default base encoding and parsed without having to supply base encoders/decoders:

```TypeScript
const v1 = CID.parse('bagaaierasords4njcts6vs7qvdjfcvgnume4hqohf65zsfguprqphs3icwea')
v1.toString()
//> 'bagaaierasords4njcts6vs7qvdjfcvgnume4hqohf65zsfguprqphs3icwea'

const v0 = CID.parse('QmdfTbBqBPQ7VNxZEYEj14VmRuZBkqFbiwReogJgS1zR1n')
v0.toString()
//> 'QmdfTbBqBPQ7VNxZEYEj14VmRuZBkqFbiwReogJgS1zR1n'
v0.toV1().toString()
//> 'bafybeihdwdcefgh4dqkjv67uzcmw7ojee6xedzdetojuzjevtenxquvyku'
```

## Multicodec Encoders / Decoders / Codecs

This library defines [`BlockEncoder`, `BlockDecoder` and `BlockCodec` interfaces](https://github.com/multiformats/js-multiformats/blob/master/src/codecs/interface.ts).
Codec implementations should conform to the `BlockCodec` interface which implements both `BlockEncoder` and `BlockDecoder`.
Here is an example implementation of JSON `BlockCodec`.

```TypeScript
export const { name, code, encode, decode } = {
  name: 'json',
  code: 0x0200,
  encode: json => new TextEncoder().encode(JSON.stringify(json)),
  decode: bytes => JSON.parse(new TextDecoder().decode(bytes))
}
```

## Multihash Hashers

This library defines [`MultihashHasher` and `MultihashDigest` interfaces](https://github.com/multiformats/js-multiformats/blob/master/src/hashes/interface.ts) and convinient function for implementing them:

```TypeScript
import * as hasher from 'multiformats/hashes/hasher'

const sha256 = hasher.from({
  // As per multiformats table
  // https://github.com/multiformats/multicodec/blob/master/table.csv#L9
  name: 'sha2-256',
  code: 0x12,

  encode: (input) => new Uint8Array(crypto.createHash('sha256').update(input).digest())
})

const hash = await sha256.digest(json.encode({ hello: 'world' }))
CID.create(1, json.code, hash)

//> CID(bagaaierasords4njcts6vs7qvdjfcvgnume4hqohf65zsfguprqphs3icwea)
```

## Traversal

This library contains higher-order functions for traversing graphs of data easily.

`walk()` walks through the links in each block of a DAG calling a user-supplied loader function for each one, in depth-first order with no duplicate block visits. The loader should return a `Block` object and can be used to inspect and collect block ordering for a full DAG walk. The loader should `throw` on error, and return `null` if a block should be skipped by `walk()`.

```TypeScript
import { walk } from 'multiformats/traversal'
import * as Block from 'multiformats/block'
import * as codec from 'multiformats/codecs/json'
import { sha256 as hasher } from 'multiformats/hashes/sha2'

// build a DAG (a single block for this simple example)
const value = { hello: 'world' }
const block = await Block.encode({ value, codec, hasher })
const { cid } = block
console.log(cid)
//> CID(bagaaierasords4njcts6vs7qvdjfcvgnume4hqohf65zsfguprqphs3icwea)

// create a loader function that also collects CIDs of blocks in
// their traversal order
const load = (cid, blocks) => async (cid) => {
  // fetch a block using its cid
  // e.g.: const block = await fetchBlockByCID(cid)
  blocks.push(cid)
  return block
}

// collect blocks in this DAG starting from the root `cid`
const blocks = []
await walk({ cid, load: load(cid, blocks) })

console.log(blocks)
//> [CID(bagaaierasords4njcts6vs7qvdjfcvgnume4hqohf65zsfguprqphs3icwea)]
```

## Legacy interface

[`blockcodec-to-ipld-format`](https://github.com/ipld/js-blockcodec-to-ipld-format) converts a multiformats [`BlockCodec`](https://github.com/multiformats/js-multiformats/blob/master/src/codecs/interface.ts#L21) into an
[`interface-ipld-format`](https://github.com/ipld/interface-ipld-format) for use with the [`ipld`](https://github.com/ipld/ipld) package. This can help bridge IPLD codecs implemented using the structure and interfaces defined here to existing code that assumes, or requires `interface-ipld-format`. This bridge also includes the relevant TypeScript definitions.

## Implementations

By default, no base encodings (other than base32 & base58btc), hash functions,
or codec implementations are exposed by `multiformats`, you need to
import the ones you need yourself.

### Multibase codecs

| bases                                                         | import                      | repo                                                                                              |
| ------------------------------------------------------------- | --------------------------- | ------------------------------------------------------------------------------------------------- |
| `base16`                                                      | `multiformats/bases/base16` | [multiformats/js-multiformats](https://github.com/multiformats/js-multiformats/tree/master/bases) |
| `base32`, `base32pad`, `base32hex`, `base32hexpad`, `base32z` | `multiformats/bases/base32` | [multiformats/js-multiformats](https://github.com/multiformats/js-multiformats/tree/master/bases) |
| `base64`, `base64pad`, `base64url`, `base64urlpad`            | `multiformats/bases/base64` | [multiformats/js-multiformats](https://github.com/multiformats/js-multiformats/tree/master/bases) |
| `base58btc`, `base58flick4`                                   | `multiformats/bases/base58` | [multiformats/js-multiformats](https://github.com/multiformats/js-multiformats/tree/master/bases) |

Other (less useful) bases implemented in [multiformats/js-multiformats](https://github.com/multiformats/js-multiformats/tree/master/bases) include: `base2`, `base8`, `base10`, `base36` and `base256emoji`.

### Multihash hashers

| hashes                                                                                                                          | import                         | repo                                                                                                               |
| ------------------------------------------------------------------------------------------------------------------------------- | ------------------------------ | ------------------------------------------------------------------------------------------------------------------ |
| `sha2-256`, `sha2-512`                                                                                                          | `multiformats/hashes/sha2`     | [multiformats/js-multiformats](https://github.com/multiformats/js-multiformats/tree/master/src/hashes)             |
| `sha3-224`, `sha3-256`, `sha3-384`,`sha3-512`, `shake-128`, `shake-256`, `keccak-224`, `keccak-256`, `keccak-384`, `keccak-512` | `@multiformats/sha3`           | [multiformats/js-sha3](https://github.com/multiformats/js-sha3)                                                    |
| `identity`                                                                                                                      | `multiformats/hashes/identity` | [multiformats/js-multiformats](https://github.com/multiformats/js-multiformats/tree/master/src/hashes/identity.js) |
| `murmur3-128`, `murmur3-32`                                                                                                     | `@multiformats/murmur3`        | [multiformats/js-murmur3](https://github.com/multiformats/js-murmur3)                                              |
| `blake2b-*`, `blake2s-*`                                                                                                        | `@multiformats/blake2`         | [multiformats/js-blake2](https://github.com/multiformats/js-blake2)                                                |

### IPLD codecs (multicodec)

| codec      | import                     | repo                                                                                                   |
| ---------- | -------------------------- | ------------------------------------------------------------------------------------------------------ |
| `raw`      | `multiformats/codecs/raw`  | [multiformats/js-multiformats](https://github.com/multiformats/js-multiformats/tree/master/src/codecs) |
| `json`     | `multiformats/codecs/json` | [multiformats/js-multiformats](https://github.com/multiformats/js-multiformats/tree/master/src/codecs) |
| `dag-cbor` | `@ipld/dag-cbor`           | [ipld/js-dag-cbor](https://github.com/ipld/js-dag-cbor)                                                |
| `dag-json` | `@ipld/dag-json`           | [ipld/js-dag-json](https://github.com/ipld/js-dag-json)                                                |
| `dag-pb`   | `@ipld/dag-pb`             | [ipld/js-dag-pb](https://github.com/ipld/js-dag-pb)                                                    |
| `dag-jose` | `dag-jose`                 | [ceramicnetwork/js-dag-jose](https://github.com/ceramicnetwork/js-dag-jose)                            |

# Install

```console
$ npm i multiformats
```

## Browser `<script>` tag

Loading this module through a script tag will make its exports available as `Multiformats` in the global namespace.

```html
<script src="https://unpkg.com/multiformats/dist/index.min.js"></script>
```

# API Docs

- <https://multiformats.github.io/js-multiformats>

# License

Licensed under either of

- Apache 2.0, ([LICENSE-APACHE](https://github.com/multiformats/js-multiformats/LICENSE-APACHE) / <http://www.apache.org/licenses/LICENSE-2.0>)
- MIT ([LICENSE-MIT](https://github.com/multiformats/js-multiformats/LICENSE-MIT) / <http://opensource.org/licenses/MIT>)

# Contribution

Unless you explicitly state otherwise, any contribution intentionally submitted for inclusion in the work by you, as defined in the Apache-2.0 license, shall be dual licensed as above, without any additional terms or conditions.

---
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