# Arcscan — Arc block explorer

> Arcscan is an independent block explorer and analytics platform for Arc, the
> Circle-built chain whose gas token is USDC. This deployment indexes Arc,
> chain ID 5042, and publishes every block, transaction, address and token on it.

The Arc network is two chains, and Arcscan is two deployments built from one source
tree. The production chain is Arc, chain ID 5042; the test chain
is Arc Testnet, chain ID 5042002. Everything under https://arc-scan.io is chain
5042 and nothing else: a figure read here is not a figure about the other chain, and
the two must never be quoted as one.
The other chain is served by a separate Arcscan deployment on its own hostname.

Three properties of Arc decide how the pages below should be read. Gas is paid in USDC, so
fees and native balances are already dollar amounts rather than a token quantity someone
converted. Consensus is BFT and a committed block is final, so there are no reorgs, no
uncles, and no pending-transaction pool to look a transaction up in. And the same dollar
appears in two decimal scales — 18 as the native balance, 6 on its ERC-20 face — which is a
presentation difference, not two assets.

## Live facts, in preference to anything written here

- [Chain metadata](https://arc-scan.io/_api/v1/chain): chain id, native and ERC-20 token decimals,
  block time, finality, node capabilities, and exactly which block ranges the index holds.
  Anything that can move is answered there rather than stated in this document.

## Entity pages

Addressable per EIP-3091. These are the product; everything else is a way of reaching them.

- https://arc-scan.io/block/{number} — also accepts a block hash; the height form is canonical
- https://arc-scan.io/tx/{hash} — tabs: /logs, /internal, /state, /raw
- https://arc-scan.io/address/{address} — tabs: /txs, /transfers, /internal, /logs, /contract
- https://arc-scan.io/token/{address} — tabs: /transfers, /info

Each carries schema.org JSON-LD: a WebPage whose mainEntity is a Dataset, plus a
BreadcrumbList. There is no schema.org vocabulary for blockchain objects, so no type is
invented for one.

## Main sections

- [Blocks](https://arc-scan.io/blocks): every block, newest first, with proposer, gas and USDC fees
- [Transactions](https://arc-scan.io/txs): every transaction, newest first
- [Internal transactions](https://arc-scan.io/txsInternal): value-carrying execution frames inside transactions
- [Token transfers](https://arc-scan.io/tokentxns): every ERC-20, ERC-721 and ERC-1155 transfer
- [Token tracker](https://arc-scan.io/tokens): contracts seen emitting a transfer, with supply and holders
- [Top accounts](https://arc-scan.io/accounts): largest holders of native USDC, with each one's exact share
- [Contracts](https://arc-scan.io/contractsVerified): every deployed contract, with deployer, creation block and verification state
- [Charts and stats](https://arc-scan.io/charts): daily and hourly series over the chain, each with a CSV export
- [Fee tracker](https://arc-scan.io/gastracker): base fee, priority-fee percentiles and what common actions cost
- [Top statistics](https://arc-scan.io/topstat): leaderboards over a stated block window
- [Node status](https://arc-scan.io/nodestatus): chain head, per-stream index coverage and lag, and what is answerable right now
- [Label cloud](https://arc-scan.io/labelcloud): every address tag provable from chain data, with the address list behind each
- [Directory](https://arc-scan.io/directory): named entities — system contracts, validators, token contracts — by name, symbol or address
- [Knowledge base](https://arc-scan.io/kb): how Arc differs from Ethereum, in prose

## API

The JSON API answers on its own hostname, https://api.arc-scan.io: `/v1/...` is the typed REST
surface, `/api?module=...&action=...` is the de-facto explorer contract, and
`/v1/stream/head` is server-sent events. Send a descriptive User-Agent — the edge
refuses several default HTTP-client agent strings before a request reaches us.

The same service is also reachable at https://arc-scan.io/_api/v1/..., which is what this site's own
pages fetch. Prefer the hostname above: `/_api/` is proxied through the web tier and shares
the limiter that serves readers.

## JSON-RPC

Arc JSON-RPC answers at `POST https://rpc.arc-scan.io`, chain 5042. No key and no sign-up.
It is callable from a browser (`access-control-allow-origin: *`), accepts at most 50 calls
per batch and 131072 bytes per body, and refuses over either with a JSON-RPC error rather
than an HTML page.

Some methods are refused by our own policy, not by the network: the `trace_` and `debug_`
families, because one measured `trace_block` returned 28,530 bytes for a single block and
this endpoint is metered on our side; signing methods, because no keys are held here — sign
locally and send `eth_sendRawTransaction`; and subscriptions, because this is HTTP only.
Each refusal carries `data.policy` naming which of those it is, and says in the message that
the decision is ours. Do not read one as a statement about Arc.

Every call and the response are kept for 24 hours; after that the response body is deleted
and what was asked and from which address remains.

## MCP

A Model Context Protocol server answers JSON-RPC 2.0 at `POST https://api.arc-scan.io/mcp`.
It exposes eight tools — chain status, block, transaction, address, address transactions,
token, token holders and search — and it reads the explorer's own index and never the
chain, so an answer is either backed by indexed data or is an explicit statement that
something is not known. Two of its rules are worth knowing before you use it: call
`arc_chain_status` before saying 'first' or 'never', because those words are only true
when `history_complete` is true; and identify tokens by address rather than by symbol,
because many contracts share one — several answer `symbol() = "USDC"` without being USDC.

A machine-readable index of all of these surfaces is at https://arc-scan.io/.well-known/api-catalog.json,
and every response on this site carries it as a `Link: …; rel="api-catalog"` header.

- [Developer guide](https://arc-scan.io/developers): terms, rate limit and worked examples, stated for chain 5042
- [API reference](https://arc-scan.io/apis): every route, generated from the service's own OpenAPI document
- [CSV export](https://arc-scan.io/exportData): bounded exports of transactions, transfers and logs
- [Advanced filter](https://arc-scan.io/advanced-filter): query transactions and transfers by address, method, asset, amount, status or range

## What this site will not claim

An explorer's only product is being believed, so a value that cannot be known is reported as
unknown and never filled in with a plausible one. Concretely:

- A block whose body the node has pruned reads *unknown, not zero* — on every tab of that
  block, including the transaction list, which does not say the block was empty.
- A transaction whose receipt has been pruned reports its outcome as unknown. A reverted
  transaction is never rendered as a successful one.
- No USD price is shown for a token whose liquidity does not clear a stated depth floor. The
  page gives the floor and the token's own measured depth instead of a number.
- A range the index has not reached is stated as unindexed rather than answered as empty.
- Details about whoever runs this deployment are shown only when they have been configured;
  where one is missing the page says so rather than naming a company or an inbox.

## Languages

Every page is published in 5 languages. English is served at the bare path;
the others take a prefix, and nothing else about the URL changes:

- /zh/ — Chinese (Simplified)
- /ko/ — Korean
- /ja/ — Japanese
- /ru/ — Russian

Each page declares its own canonical and its own hreflang set. Language is decided by the
URL alone — nothing here negotiates on Accept-Language — so a page fetched with no prefix
is the English one.

## Crawling

- https://arc-scan.io/robots.txt is authoritative about what may be fetched, including several user
  agents that are refused outright.
- https://arc-scan.io/sitemap.xml is a sitemap index; the child sitemaps are what to walk.

## Optional

- [About](https://arc-scan.io/about): what Arcscan is and what it is independent of
- [Terms](https://arc-scan.io/terms): acceptable use, including automated access
- [Privacy](https://arc-scan.io/privacy): what is logged, and what is not
- [Bug bounty](https://arc-scan.io/bugbounty): reporting terms, scope and safe harbour
- [Contact](https://arc-scan.io/contactus): how to reach us
- [security.txt](https://arc-scan.io/.well-known/security.txt): RFC 9116 security contact