What blockchain is Polymarket on?

Polygon PoS, chain ID 137, and nothing else

Polymarket has run on Polygon since launch and still does. Its developer documentation lists Polygon mainnet as the sole deployment network for every contract the platform uses, and describes that contracts page as the single source of truth for the addresses. There is no Ethereum mainnet deployment, no Base or Arbitrum version, and no multi-chain arrangement to keep track of. When a market price moves, the resulting fill lands in a Polygon block.

Polygon PoS is a proof-of-stake chain with its own validator set, designed to be compatible with Ethereum tooling rather than to be part of Ethereum. The reason the distinction matters here is cost. A busy prediction market settles a large number of individually small fills, many of them worth a few dollars, and at Ethereum mainnet fees the gas on a five-dollar fill could exceed the fill. Polygon fees are a small fraction of a cent, which is what makes an openly settled order-book market economic to operate.

The contracts below are the ones that do the work. The addresses are worth dating, because Polymarket migrated both its exchange and its collateral contracts on April 28, 2026, an upgrade that introduced CTF Exchange V2 and replaced the older bridged-USDC collateral. Older write-ups that list pre-April addresses are describing contracts the platform has moved on from.

What is actually on the chain, and what is not

Calling Polymarket an on-chain market is accurate but incomplete, and the incomplete version causes real confusion. The order book is not on Polygon. Polymarket runs what its developer community calls a hybrid design: a participant signs an order off-chain using the EIP-712 typed-data standard, an operator run by Polymarket matches compatible orders on its own servers, and only the matched result is packaged into a transaction and submitted to the chain, where the exchange contract performs the swap atomically.

That split has consequences a reader can feel. Placing an order or cancelling one costs nothing and produces no on-chain trace, which is why an order that never fills leaves no public record. Matching and queue priority are decided by a centralised operator. Custody is not: funds sit in the participant's own contract account and the exchange contract can only perform swaps against signed orders. What you gain in speed you give up in transparency of intent, and what you keep is control of the balance.

The resting depth a reader sees quoted on a market page comes from the off-chain book, not from the chain, which is one reason depth and settled volume can tell very different stories about the same market. How that book is structured is covered in what is a Polymarket order book.

Outcome tokens, collateral, and the April 2026 change

The tokens themselves come from the Conditional Token Framework, an open standard originally developed by Gnosis. It turns collateral into ERC-1155 tokens that each represent one outcome of one market. A unit of collateral splits into a full set of outcome tokens, that set can be merged back into collateral, and once a market resolves the winning token is redeemed for one dollar while the others are worth nothing. Prices between one cent and ninety-nine cents fall out of that structure, which is why a Polymarket price reads directly as an implied probability. The reading itself is covered in how to read implied probability.

The collateral changed recently. On April 28, 2026 Polymarket migrated from bridged USDC.e to pUSD, its own ERC-20 collateral token on Polygon, backed one for one by USDC with the backing enforced on-chain by the contract rather than by an algorithm or a fractional reserve. Balances carried over at one to one with no fee, trading paused for about an hour, and resting limit orders were cancelled. Day to day the experience did not change, and the full currency picture sits in what currency does Polymarket use.

One more contract matters to anyone reading wallet data. Each account gets a proxy wallet, a smart contract account deployed on first login, which holds the balance and signs trades on the participant's behalf. A relayer submits the transactions and covers the gas, so a participant does not need to hold POL, formerly MATIC. The address that appears on a block explorer is that proxy contract, not the email login or browser wallet behind it, which is a frequent source of confusion and is unpacked in what is a Polymarket proxy wallet.

Why the chain is the reason this site exists

For most readers the practical answer to the chain question is not the chain name. It is what settling on a public chain implies: every filled trade, every open position, and every realised profit or loss on the original market is permanently recorded under a wallet address and readable by anyone, without permission and without an account. No equivalent record exists for a conventional venue, where the order history is the operator's private property.

That is the raw material behind the large-wallet coverage on this site. The traders index and the whale activity page are built from that public settlement record rather than from anything disclosed to us, and the collection cadence and limits are set out on the methodology page. The same transparency cuts the other way for participants: a wallet is pseudonymous rather than anonymous, and its full history is visible the moment anyone connects the address to a person.

It also sets a hard boundary on what any tracker can see. Because matching happens off-chain, unfilled interest is invisible; because Polymarket US keeps no public ledger, a growing share of the brand's total activity is simply outside the data. A figure described as covering Polymarket usually covers the Polygon venue alone, and that gap widens as the regulated exchange grows.

The US exchange is on no chain at all

Since December 2025 the Polymarket brand has covered two venues that work quite differently. The original market is the Polygon one described above. Polymarket US, operated by QCX LLC, is a CFTC-regulated designated contract market: it verifies identity, takes and settles ordinary US dollars through regulated intermediaries, and keeps its records internally the way any derivatives exchange does. No wallet, no stablecoin, no public ledger.

So the answer to which blockchain Polymarket is on depends on which Polymarket is meant, and the two are easy to conflate because they price similar events under one name. Everything Cent Signals reports comes from the on-chain venue, for the simple reason that it is the only one that publishes a record to read. The wider regulatory picture is covered in is Polymarket legal in the US.

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