Moonriver – Moonbeam's Canary Network on Kusama

Moonriver RPC
With Dwellir, you get access to our global Moonriver network which always routes your API requests to the nearest available location, ensuring low latency and the fastest speeds.

Get your API key →

Why Build on Moonriver?

Moonriver is Moonbeam’s canary network on Kusama, delivering the same Substrate foundation and EVM compatibility with faster iteration cycles. It is ideal for deploying and testing EVM and Substrate-based functionality under real economic conditions before promoting to Moonbeam.

⚡ Fast Iteration, Real Economics

Rapid runtime upgrade cadence enables shipping features earlier than Moonbeam.
Real MOVR token economics and on-chain governance for production-like validation.
Shared Kusama security provides fast finality while enabling experimentation.

🔗 EVM + Substrate Interop

Full EVM compatibility via Frontier with MetaMask, Hardhat, and Solidity tooling.
Native Substrate interfaces for storage, blocks, and runtime APIs.
Seamless migration path to Moonbeam after validation on Moonriver.

Quick Start with Moonriver

Connect to Moonriver production endpoints with Dwellir’s global network.

🔗 RPC Endpoints

Moonriver (Kusama Parachain 2023)

Mainnet

Archive-enabled WebSocket and HTTPS endpoints with global routing.

WSS

wss://api-moonriver.n.dwellir.com/YOUR_API_KEY

HTTPS

https://api-moonriver.n.dwellir.com/YOUR_API_KEY

✓ Archive Node✓ Trace API✓ Debug API✓ WebSocket✓ Kusama parachain 2023

Quick Connect:

curl -X POST https://api-moonriver.n.dwellir.com/YOUR_API_KEY \
  -H "Content-Type: application/json" \
  -d '{"jsonrpc":"2.0","method":"chain_getBlock","params":[],"id":1}'

Installation & Setup

curl (HTTP JSON-RPC)
JavaScript (polkadot.js)
Rust (subxt)
Python (py-substrate-interface)

curl -s https://api-moonriver.n.dwellir.com/YOUR_API_KEY \
  -H 'Content-Type: application/json' \
  -d '{
    "jsonrpc": "2.0",
    "method": "chain_getHeader",
    "params": [],
    "id": 1
  }'

import { ApiPromise, WsProvider } from '@polkadot/api';

async function main() {
  const provider = new WsProvider('wss://api-moonriver.n.dwellir.com/YOUR_API_KEY');
  const api = await ApiPromise.create({ provider });

  const [chain, version] = await Promise.all([
    api.rpc.system.chain(),
    api.rpc.system.version(),
  ]);

  console.log(`Connected to ${chain.toString()} v${version.toString()}`);

  // Subscribe to new blocks
  const unsub = await api.rpc.chain.subscribeNewHeads((header) => {
    console.log(`New block #${header.number} at ${header.hash}`);
  });

  // Stop after a short period
  setTimeout(async () => {
    await unsub();
    await api.disconnect();
  }, 15000);
}

main().catch(console.error);

use subxt::{OnlineClient, PolkadotConfig};

#[tokio::main]
async fn main() -> Result<(), Box<dyn std::error::Error>> {
    let api = OnlineClient::<PolkadotConfig>::from_url(
        "wss://api-moonriver.n.dwellir.com/YOUR_API_KEY"
    ).await?;

    let header = api.rpc().block_header(None).await?.expect("latest header");
    println!("Latest block: #{:?} (hash {:?})", header.number, header.hash());

    Ok(())
}

from substrateinterface import SubstrateInterface

substrate = SubstrateInterface(
    url="wss://api-moonriver.n.dwellir.com/YOUR_API_KEY"
)

chain = substrate.rpc_request("system_chain", [])
print(f"Connected to {chain['result']}")

head = substrate.rpc_request("chain_getFinalizedHead", [])
print(f"Finalized head: {head['result']}")

Network Information

Genesis Hash

0x401a1f9d…1474b

chain_getBlockHash(0)

Native Token

MOVR

18 decimals

SS58 Prefix

1285

system_properties

Relay / Para ID

Kusama / 2023

Parachain on Kusama

Runtime Spec Version

3900

As of 9 Oct 2025

Transaction Version

state_getRuntimeVersion

Explorer

Moonscan

moonriver.moonscan.io

Example Values Used in Docs

These chain-specific variables are used across Moonriver examples:

exampleEvmAddress: 0x6bEc0BCA2F15876f675f2C38958Ff986551e4db1

exampleBlockHash: 0x1849c7bc2c547b315fef716c6f2fb6f5e256da60482a013286caf975d035f766

exampleBlockNumberHex: 0xcd64f5

explorerMainnet: https://moonriver.moonscan.io

Substrate JSON-RPC API Reference

Moonriver exposes standard Substrate RPC namespaces for node telemetry, block production, storage access, and fee estimation. Open method guides from the dropdown below.

Available JSON-RPC Methods

System & Runtime

Identify the chain, runtime versions, and node health.

Chain Data & Finality

Inspect blocks, headers, and finality streams.

State Access & Storage

Query storage, metadata, and runtime entry points.

Authoring & Sessions

Submit extrinsics and manage session keys.

RPC Introspection

Discover supported RPC namespaces and versions.

Get your API key

Get your API key →

Common Integration Patterns

Track new blocks (subscriptions)

const unsub = await api.rpc.chain.subscribeNewHeads((header) => {
  console.log(`New #${header.number} (${header.hash})`);
});

Paginate large storage scans

const page = await api.rpc.state.getKeysPaged(
  api.query.system.account.keyPrefix(),
  100,
  '0x',
  null
);
console.log('Fetched', page.length, 'System.Account keys');

Estimate fees before broadcast

const ext = api.tx.balances.transferAllowDeath(dest, amount);
const info = await api.rpc.payment.queryInfo(ext.toHex());
console.log(`PartialFee: ${info.partialFee.toHuman()}`);

Performance Best Practices

Prefer WebSocket connections for subscriptions and multi-round queries.
Cache runtime metadata and reuse a single ApiPromise instance.
Use state_getKeysPaged for large scans; avoid full-chain traversals.
Exponential backoff on retries for transient -32010/TooManyRequests errors.

Troubleshooting

WebSocket failure – Verify your API key and outbound TCP/443. Try HTTPS for single calls.
Type mismatches – Refresh metadata after runtime upgrades (api.runtimeVersion).
Invalid address – Moonriver uses SS58 prefix 1285 for Substrate addresses; EVM 0x… accounts are also supported in the runtime.
Extrinsic rejected – Decode with api.registry.findMetaError to surface module/error.

Smoke Tests

Run these checks against production endpoints (values as of 9 Oct 2025):

# Node health
curl -s https://api-moonriver.n.dwellir.com/YOUR_API_KEY \
  -H 'Content-Type: application/json' \
  -d '{"jsonrpc":"2.0","id":1,"method":"system_health","params":[]}'

# Latest block header
curl -s https://api-moonriver.n.dwellir.com/YOUR_API_KEY \
  -H 'Content-Type: application/json' \
  -d '{"jsonrpc":"2.0","id":1,"method":"chain_getHeader","params":[]}'

# Runtime version
curl -s https://api-moonriver.n.dwellir.com/YOUR_API_KEY \
  -H 'Content-Type: application/json' \
  -d '{"jsonrpc":"2.0","id":1,"method":"state_getRuntimeVersion","params":[]}'

Migration Guide

Endpoints – Replace Polkadot/Moonbeam URLs with https://api-moonriver.n.dwellir.com/YOUR_API_KEY or wss://api-moonriver.n.dwellir.com/YOUR_API_KEY.
Addresses – Use SS58 prefix 1285 for Substrate-style addresses when needed; EVM 0x… addresses remain valid for account state.
Runtime types – Update custom type bundles as needed and refresh metadata caches after upgrades (specVersion 3900 on Oct 9, 2025).
Fees – Calibrate using payment_queryInfo/payment_queryFeeDetails for MOVR-denominated fees.
XCM/Parachain – Confirm HRMP channels and destination parachain IDs for XCM; Moonriver is parachain 2023 on Kusama.

Why Build on Moonriver?​

⚡ Fast Iteration, Real Economics​

🔗 EVM + Substrate Interop​

Quick Start with Moonriver​

🔗 RPC Endpoints

Installation & Setup​

Network Information​