# @helia/block-brokers
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> Block brokers for Helia
# About
This module contains Helia block brokers, currently for [bitswap](https://docs.ipfs.tech/concepts/bitswap/)
and [Trustless Gateways](https://specs.ipfs.tech/http-gateways/trustless-gateway/).
## Trustless Gateway Block Broker
The TrustlessGatewayBlockBroker fetches blocks from HTTP gateways.
## Example - Customizing fetch requests with custom headers
It is possible to modify outgoing requests to (for example) include
authentication information (such as a JWT token in a header).
```typescript
import { createHelia } from 'helia'
import { trustlessGateway } from '@helia/block-brokers'
import { unixfs } from '@helia/unixfs'
import { CID } from 'multiformats/cid'
import { concat } from 'uint8arrays/concat'
import all from 'it-all'
const helia = await createHelia({
blockBrokers: [
trustlessGateway({
transformRequestInit: (requestInit) => {
// modify the request init object as required
requestInit.headers = {
...requestInit.headers,
'User-Agent': 'Helia Example Script'
}
return requestInit
}
})
]
})
const cid = CID.parse('bafkreife2klsil6kaxqhvmhgldpsvk5yutzm4i5bgjoq6fydefwtihnesa')
const fs = unixfs(helia)
for await (const chunk of fs.cat(cid, {
signal: AbortSignal.timeout(10_000)
})) {
console.info(chunk)
}
```
# Install
```console
$ npm i @helia/block-brokers
```
## Browser `
```
# API Docs
-
# License
Licensed under either of
- Apache 2.0, ([LICENSE-APACHE](https://github.com/ipfs/helia/blob/main/packages/block-brokers/LICENSE-APACHE) / )
- MIT ([LICENSE-MIT](https://github.com/ipfs/helia/blob/main/packages/block-brokers/LICENSE-MIT) / )
# Contribute
Contributions welcome! Please check out [the issues](https://github.com/ipfs/helia/issues).
Also see our [contributing document](https://github.com/ipfs/community/blob/master/CONTRIBUTING_JS.md) for more information on how we work, and about contributing in general.
Please be aware that all interactions related to this repo are subject to the IPFS [Code of Conduct](https://github.com/ipfs/community/blob/master/code-of-conduct.md).
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.
[](https://github.com/ipfs/community/blob/master/CONTRIBUTING.md)