less net work for networks

#What is iroh?

Iroh gives you an API for dialing by public key. You say “connect to that phone”, iroh will find & maintain the fastest connection for you, regardless of where it is.

#Hole-punching

The fastest route is a direct connection, so if necessary, iroh tries to hole-punch. Should this fail, it can fall back to an open ecosystem of public relay servers. To ensure these connections are as fast as possible, we continuously measure iroh.

#Built on QUIC

Iroh uses noq to establish QUIC connections between endpoints. This way you get authenticated encryption, concurrent streams with stream priorities, a datagram transport and avoid head-of-line-blocking out of the box.

#Compose Protocols

Use pre-existing protocols built on iroh instead of writing your own:

• iroh-blobs for BLAKE3-based content-addressed blob transfer scaling from kilobytes to terabytes
• iroh-gossip for establishing publish-subscribe overlay networks that scale, requiring only resources that your average phone can handle
• iroh-docs for an eventually-consistent key-value store of iroh-blobs blobs

#Getting Started

#Rust Library

It's easiest to use iroh from rust. Install it using cargo add iroh, then on the connecting side:

const ALPN: &[u8] = b"iroh-example/echo/0";

let endpoint = Endpoint::bind().await?;

// Open a connection to the accepting endpoint
let conn = endpoint.connect(addr, ALPN).await?;

// Open a bidirectional QUIC stream
let (mut send, mut recv) = conn.open_bi().await?;

// Send some data to be echoed
send.write_all(b"Hello, world!").await?;
send.finish()?;

// Receive the echo
let response = recv.read_to_end(1000).await?;
assert_eq!(&response, b"Hello, world!");

// As the side receiving the last application data - say goodbye
conn.close(0u32.into(), b"bye!");

// Close the endpoint and all its connections
endpoint.close().await;

And on the accepting side:

let endpoint = Endpoint::bind().await?;

let router = Router::builder(endpoint)
    .accept(ALPN.to_vec(), Arc::new(Echo))
    .spawn()
    .await?;

// The protocol definition:
#[derive(Debug, Clone)]
struct Echo;

impl ProtocolHandler for Echo {
    async fn accept(&self, connection: Connection) -> Result<()> {
        let (mut send, mut recv) = connection.accept_bi().await?;

        // Echo any bytes received back directly.
        let bytes_sent = tokio::io::copy(&mut recv, &mut send).await?;

        send.finish()?;
        connection.closed().await;

        Ok(())
    }
}

The full example code with more comments can be found at echo.rs.

Or use one of the pre-existing protocols, e.g. iroh-blobs or iroh-gossip.

#Other Languages

If you want to use iroh from other languages, make sure to check out iroh-ffi, the repository for FFI bindings.

#Links

• Introducing Iroh (video)
• Iroh Documentation
• Iroh Examples
• Iroh Experiments

#Repository Structure

This repository contains a workspace of crates:

• iroh: The core library for hole-punching & communicating with relays.
• iroh-relay: The relay client and server implementation. This is the code we run in production for the public relays (and you can, too!).
• iroh-base: Common types like EndpointId or RelayUrl.
• iroh-dns-server: DNS server implementation powering the DNS/Pkarr address lookup for EndpointIds, running at dns.iroh.link.

#License

Copyright 2025 N0, INC.

This project is licensed under either of

• Apache License, Version 2.0, (LICENSE-APACHE or https://www.apache.org/licenses/LICENSE-2.0)
• MIT license (LICENSE-MIT or https://opensource.org/licenses/MIT)

at your option.

#Contribution

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