> ## Documentation Index
> Fetch the complete documentation index at: https://docs.hedera.com/llms.txt
> Use this file to discover all available pages before exploring further.

# JSON-RPC Relay

> What the Hiero JSON-RPC Relay is, who runs it, and when to host your own.

The Hiero JSON-RPC Relay is an open-source service that speaks the Ethereum JSON-RPC protocol on top of the Hedera network. EVM tools (Hardhat, Foundry, Ethers.js, Viem, MetaMask) speak JSON-RPC; Hedera consensus nodes speak gRPC. The relay translates between the two, plus pulls historical state from a mirror node.

Repository: [`hiero-ledger/hiero-json-rpc-relay`](https://github.com/hiero-ledger/hiero-json-rpc-relay). License: Apache-2.0.

## Three ways to get an RPC endpoint

For most teams, "running the relay" means picking one of three options based on the use case.

| Option                                                                                                                                             | When it fits                                                              | Cost                     |
| -------------------------------------------------------------------------------------------------------------------------------------------------- | ------------------------------------------------------------------------- | ------------------------ |
| [Hashio](https://github.com/hiero-ledger/hiero-json-rpc-relay) (free public relay, development use only)                                           | Development, hobby projects, low-volume reads                             | Free, throttled          |
| [Third-party managed provider](/evm/development/json-rpc#community-hosted-json-rpc-relays) (Arkhia, Validation Cloud, Hgraph, QuickNode, thirdweb) | Production traffic with SLAs                                              | Paid, varies by provider |
| Self-hosted                                                                                                                                        | Production workloads where you control config, retention, and rate limits | Infra cost only          |

Hashio is the easiest path for "I just need a testnet endpoint right now." It's *not* intended for production traffic.

## Public endpoints

| Network    | Chain ID | Hashio endpoint                    |
| ---------- | :------: | ---------------------------------- |
| Mainnet    |   `295`  | `https://mainnet.hashio.io/api`    |
| Testnet    |   `296`  | `https://testnet.hashio.io/api`    |
| Previewnet |   `297`  | `https://previewnet.hashio.io/api` |

Drop one of these into MetaMask, Hardhat, or Foundry as your RPC URL with the matching chain ID. You're done. For production, replace Hashio with your own relay or a commercial provider.

## When to run your own

Self-hosting makes sense when you need any of:

* Higher throughput than community endpoints throttle to
* Custom rate-limiting rules per consumer
* Tighter control over which mirror node the relay reads from
* An RPC endpoint inside a private VPC, not on the public internet
* Specific log retention, metrics, or audit requirements

If none of these apply, a managed provider is almost always less operational work.

<Tip>
  **Testing relay configuration locally?** [Solo](https://solo.hiero.org/docs/) ships with a JSON-RPC relay as part of its full-stack Kubernetes deployment. Use it to test custom chain IDs, rate limits, and mirror node URL wiring against a local network before deploying to production. See [Using Solo with EVM tools](https://solo.hiero.org/docs/using-solo/using-solo-with-evm-tools/) for connection details.
</Tip>

## Next steps

<CardGroup cols={2}>
  <Card title="Setup" icon="wrench" href="/operators/json-rpc/setup">
    Install and run the relay locally or in a container orchestrator.
  </Card>

  <Card title="Configuration" icon="sliders" href="/operators/json-rpc/configuration">
    Environment variables, chain ID, mirror node URL, caching, rate limits.
  </Card>
</CardGroup>