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

# Arc API reference: getting started

> Get started building on Arc with Chainstack. Access the JSON-RPC API on Circle's USDC-native EVM layer 1, including the custom arc_* consensus methods.

## What is Arc?

Arc is an EVM-compatible layer 1 from Circle. It pairs the [Reth](https://github.com/paradigmxyz/reth) execution client with [Malachite](https://github.com/circlefin/malachite) BFT consensus, and it uses USDC for gas instead of a volatile native token.

<Info>
  Arc is testnet only. Circle has not launched a mainnet yet, so every endpoint and example on these pages targets Arc Testnet.
</Info>

### Key characteristics

* **USDC as gas** — transaction fees are paid in USDC, so costs are predictable in dollar terms.
* **Sub-second blocks** — Arc produces a block roughly every 0.5 seconds under Malachite BFT consensus, with deterministic finality rather than probabilistic confirmation.
* **Standard EVM surface** — the `eth_*` methods behave as they do on any Reth node, so existing tooling works unchanged.
* **Full debug and trace** — both the `debug_*` namespace and the Parity-style `trace_*` namespace are available.
* **A custom `arc_*` namespace** — two methods that have no equivalent on other chains, covering the node build and the consensus commit certificate.

## Network details

| Property         | Value                  |
| ---------------- | ---------------------- |
| Network          | Arc Testnet            |
| Chain ID         | `5042002` (`0x4cef52`) |
| Native gas token | USDC                   |
| Execution client | Reth                   |
| Consensus        | Malachite BFT          |
| Block time       | \~0.5s                 |
| Node modes       | Full and Archive       |

## Namespaces

Chainstack Arc nodes expose `eth`, `debug`, `trace`, `txpool`, `net`, `web3`, and `rpc`, plus the custom `arc` namespace.

<Warning>
  `rpc_modules` does not list `arc`, because that namespace is registered outside the standard module registry. Both `arc_*` methods work regardless. Do not use `rpc_modules` as an inventory of what the node serves — see [Arc methods](/docs/arc-methods) for verified per-method availability.
</Warning>

## Two things that differ from other EVM chains

**Pending transactions are not observable.** Arc rejects both `eth_newPendingTransactionFilter` and `eth_subscribe("newPendingTransactions")` with `-32001`. The `txpool_*` methods do work, so you can inspect the pool, but you cannot stream new pending transactions as they arrive.

**Most historical queries bill as archive.** The standard rule is that a request 127 or more blocks behind the tip bills as archive. At roughly 0.5 seconds per block that covers only about a minute of history, against roughly 25 minutes on Ethereum. See [Request units](/docs/request-units#evm-methods-affected-by-block-age).

## Getting an endpoint

1. [Sign up with Chainstack](https://console.chainstack.com/).
2. [Deploy a node](/docs/manage-your-networks#join-a-public-network) on Arc Testnet.
3. [View node access and credentials](/docs/manage-your-node#view-node-access-and-credentials).

Every method page in this section carries a **Try it** panel wired to a public Arc Testnet endpoint, so you can run any call before deploying anything.

## Where to go next

<CardGroup cols={2}>
  <Card title="Arc namespace" icon="angle-right" iconType="solid" href="/reference/arc-namespace-rpc-methods" horizontal />

  <Card title="Method availability" icon="angle-right" iconType="solid" href="/docs/arc-methods" horizontal />

  <Card title="Debug and trace" icon="angle-right" iconType="solid" href="/reference/arc-debug-and-trace-rpc-methods" horizontal />

  <Card title="Transaction pool" icon="angle-right" iconType="solid" href="/reference/arc-txpool-rpc-methods" horizontal />
</CardGroup>