Arc developer reference
Arc mainnet is chain ID 5042 (0x13b2); its public RPC is https://rpc.mainnet.arc.io, its block explorer is https://explorer.arc.io (Blockscout), and gas is paid in USDC.
Each answer links its source. Projects come from the Arc ecosystem directory, last reviewed 2026-11-01. Chain facts: Arc blockchain: facts with sources.
- What is the Arc mainnet chain ID and RPC URL?
- How do I deploy a smart contract on Arc?
- What block explorer does Arc use?
- How do I accept USDC payments in my app on Arc?
- Is there an MCP server for Arc blockchain data?
- How can an AI agent pay for an API with USDC on Arc using x402?
What is the Arc mainnet chain ID and RPC URL?
Arc mainnet's chain ID is 5042 (0x13b2) and its public RPC URL is https://rpc.mainnet.arc.io, run by Circle with no API key. (source)
| Setting | Value |
|---|---|
| Network name | Arc Mainnet |
| Chain ID | 5042 (0x13b2) |
| RPC | https://rpc.mainnet.arc.io |
| WebSocket | wss://rpc.mainnet.arc.io |
| Currency | USDC, 18 decimals as the native gas token iThe ERC-20 interface of the same USDC is at 0x3600000000000000000000000000000000000000 with 6 decimals; Arc's docs say not to show the two as separate balances. |
| Explorer | https://explorer.arc.io |
Public RPC endpoints
8 endpoints: 7 answer without a key.
| Provider | HTTP endpoint | Key | Up, 24 h | Up, 7 days | Latency, 24 h median | Blocks behind | Source |
|---|---|---|---|---|---|---|---|
| Arc (Circle) | https://rpc.mainnet.arc.io | None | 100% | 100% | 34 ms | 0 | source |
| Blockdaemon | https://rpc.blockdaemon.mainnet.arc.io | None | 100% | 100% | 14 ms | 0 | source |
| dRPC | https://rpc.drpc.mainnet.arc.io | None | 100% | 100% | 28 ms | 0 | source |
| QuickNode | https://rpc.quicknode.mainnet.arc.io | None | 100% | 100% | 34 ms | 0 | source |
| PublicNode (Allnodes) | https://arc-rpc.publicnode.com | None | 100% | 100% | 36 ms | 0 | source |
| thirdweb | https://5042.rpc.thirdweb.com | None | Rate-limited iEvery check from our server in the last 24 h got HTTP 429, the provider's rate limit for use without a key. It answers from other networks; a key lifts the limit. | – | – | – | source |
| Tenderly | https://arc.gateway.tenderly.co | None | 100% | 100% | 18 ms | 0 | source |
| Alchemy | https://arc-mainnet.g.alchemy.com/v2/YOUR_API_KEY | API key | Not measured | – | – | – | source |
Checked hourly by Registrai; last check 8 Nov 2026, 22:17 UTC, 6 of 7 endpoints up, 1 rate-limited. i
Every hour, from one server, Registrai calls eth_chainId once and eth_blockNumber 3 times, 1 s apart, on each endpoint that needs no key, all endpoints at the same time. A check is up when the chain ID is 5042 and at least 2 of the 3 block-number calls answer within 5 s. Latency is the median time of those calls, so it includes the network path from our server; from elsewhere it differs. An HTTP 429 (the provider's rate limit for use without a key) is shown as rate-limited and left out of uptime. Blocks behind: the highest block any endpoint returned in the last round minus this endpoint's; a block or two is timing, not lag.
How do I deploy a smart contract on Arc?
Arc is EVM-compatible, so Solidity contracts deploy as on Ethereum, with gas paid in USDC; Arc's docs use Arc Foundry (arc-forge, arc-cast, arc-anvil), a fork of Foundry that supports Arc's differences from Ethereum. (source, EVM differences)
- Install Arc Foundry from its releases (how-to).
- Fund the deploying address with USDC on Arc for gas: how to get USDC onto Arc.
- Deploy:
arc-forge create src/Counter.sol:Counter --rpc-url https://rpc.mainnet.arc.io --private-key $PRIVATE_KEY --broadcast - Verify the source on the explorer:
arc-forge verify-contractwith--verifier blockscout(Arc's tutorial shows it against the testnet explorer's/api/), or submit it on explorer.arc.io.
Arc's tutorial runs these steps on testnet (chain ID 5042002, faucet USDC); on mainnet the RPC and chain ID above apply.
Developer tools live on Arc
| Project | What it does on Arc | Status | Evidence |
|---|---|---|---|
| Allium | Onchain data platform; its data catalog and APIs index Arc (raw, decoded, DEX, lending, stablecoin and RWA tables). | Live on mainnet | evidence |
| Crossmint | Stablecoin and wallet infrastructure for enterprises. | Live on mainnet | evidence |
| DFNS | Wallet-as-a-service and key management platform for banks, fintechs and businesses. | Live on mainnet | evidence |
| Dune | Onchain data query platform; it indexes Arc under the arc schema (blocks, transactions, logs, traces, decoded contracts). | Live on mainnet | evidence |
| HIFI | API platform for moving money across fiat rails and stablecoins, covering cross-border payments, payouts and stablecoin minting. | Live on mainnet | evidence |
| Lagoon | Vault infrastructure for onchain asset management built on the ERC-7540 asynchronous vault standard. | Live on mainnet | evidence |
| Meter | Pay-per-call API gateway: a caller pays a registered endpoint in USDC through the MeterRegistry contract and sends the transaction hash as… | Live on mainnet | evidence |
| Pimlico | Account abstraction infrastructure providing ERC-4337 bundler and paymaster services. | Live on mainnet | evidence |
| Team Finance | Token tooling platform for creating tokens and for locking liquidity, team tokens and NFTs, with vesting, staking pools, airdrops and… | Live on mainnet | evidence |
| Thirdweb | Web3 developer platform for wallets, payments, bridging and tokens. | Live on mainnet | evidence |
| ZeroDev | Smart account infrastructure covering account abstraction, gas sponsorship, session keys and embedded wallets. | Live on mainnet | evidence |
What block explorer does Arc use?
Arc uses Blockscout as its block explorer, at https://explorer.arc.io for mainnet. (source)
Indexers and data
| Project | What it does on Arc | Status | Evidence |
|---|---|---|---|
| Blockscout | Open-source blockchain explorer. | Live on mainnet | evidence |
| Goldsky | Blockchain data and automation platform. | Live on mainnet | evidence |
| Allium | Onchain data platform; its data catalog and APIs index Arc (raw, decoded, DEX, lending, stablecoin and RWA tables). | Live on mainnet | evidence |
| Dune | Onchain data query platform; it indexes Arc under the arc schema (blocks, transactions, logs, traces, decoded contracts). | Live on mainnet | evidence |
| Alchemy | Node, data and wallet API provider. | Live on mainnet | evidence |
| DefiLlama | DeFi data aggregator that tracks Arc as a chain (chain ID 5042) with TVL and protocol listings. | Live on mainnet | evidence |
Arc's docs also list Envio, Pinax, The Graph, thirdweb and Zerion as data indexers (source). Registrai's own data API serves app payments, the Arc indices and the directory.
How do I accept USDC payments in my app on Arc?
Two ways: receive USDC directly to your own address and confirm each payment from USDC's transfer events, or take payments through a provider live on Arc.
- Directly: USDC is Arc's native token (18 decimals) and also an ERC-20 at
0x3600000000000000000000000000000000000000(6 decimals); Arc's docs describe which events to watch (USDC system events) and a checkout flow (eCommerce checkout). - Per request, for APIs and AI agents: x402 (below).
Payment providers for developers
| Project | What it does on Arc | Status | Evidence |
|---|---|---|---|
| HIFI | API platform for moving money across fiat rails and stablecoins, covering cross-border payments, payouts and stablecoin minting. | Live on mainnet | evidence |
| Meter | Pay-per-call API gateway: a caller pays a registered endpoint in USDC through the MeterRegistry contract and sends the transaction hash as… | Live on mainnet | evidence |
Payment apps already taking USDC on Arc: apps that accept USDC on Arc.
Is there an MCP server for Arc blockchain data?
Yes. Registrai runs a read-only MCP server for Arc blockchain data at https://builder.registrai.cc/api/mcp (Streamable HTTP, no sign-in or key), listed in the MCP registry as cc.registrai/arc-data. It serves the same data as the API: stablecoin payments per app, the Arc indices, the ecosystem directory and Arc chain figures. Tools and setup
claude mcp add --transport http registrai-arc https://builder.registrai.cc/api/mcp
Arc's documentation has its own MCP server at https://docs.arc.io/mcp; it searches the docs and does not serve chain data (source).
How can an AI agent pay for an API with USDC on Arc using x402?
The API answers HTTP 402 with its price; the agent signs a USDC payment authorization (EIP-3009) and retries the request with it attached. On Arc, Circle Gateway Nanopayments settles these in batches, gas-free for the agent, after a one-time USDC deposit. (x402, Nanopayments; Arc is supported: Gateway blockchains)
Circle's sample agent that pays API endpoints in USDC on Arc: circlefin/arc-nanopayments.
x402 services on Arc
| Project | What it does on Arc | Status | Evidence |
|---|---|---|---|
| ArcLens | Arc ecosystem directory and data platform with project listings, campaigns, an explorer and a pay-per-call AI agent API over x402. | Live on mainnet | evidence |
| Arclight | Also runs an x402 payment facilitator. | Live on mainnet | evidence |
| BlockRun | Pay-per-call gateway to AI models and data APIs, paid in USDC on Arc through the x402 protocol. | Live on mainnet | evidence |
Announced: Orthogonal
Arc in numbers · Developer tools for Arc · Infrastructure for Arc