Poly Syncer accepts USDC on two networks: BNB Smart Chain and Ethereum mainnet. Choose BNB Smart Chain for low fees (around $0.20 per transfer, ~3-second finality) and Ethereum for institutional-grade settlement (around $2–$15 per transfer, ~12-second slot finality). Polygon is currently under maintenance and not accepted. The network you choose affects gas, confirmation time, and decimal handling, but not the dollar value of your Polymarket bot subscription — one USDC is one USDC on either rail, and every payment is verified on-chain before access to the Polymarket copy trade engine is granted.
USDC in 60 seconds
USDC is a fully-reserved US-dollar stablecoin issued by Circle. Each unit is backed 1:1 by a reserve held in cash and short-duration US Treasuries, with monthly attestations published by an independent accounting firm. The token's smart contracts on every supported chain are pausable by Circle for compliance reasons, but in normal operation USDC behaves exactly like a regular ERC-20: balances live on-chain, transfers settle on-chain, and there is no off-chain ledger between you and the recipient.
Three properties matter for paying a subscription:
- Final settlement. Once a transfer is included in a confirmed block, it is irreversible. There is no chargeback rail.
- Native to many chains. Circle deploys canonical USDC on Ethereum, BNB Smart Chain, Solana, Base, Arbitrum, and others. Poly Syncer currently accepts the Ethereum and BNB Smart Chain deployments.
- Verifiable in your own wallet. You can read the contract directly on a block explorer and confirm balances without trusting any front-end.
Which networks Poly Syncer accepts (and which it doesn't)
Poly Syncer currently supports two USDC payment rails:
- BNB Smart Chain (BSC) — the default for cost-sensitive users.
- Ethereum mainnet — the default for institutional users paying from custody-managed treasuries.
A third rail, Polygon PoS, is currently under maintenance while Circle's bridged-to-native USDC migration is finalized on our side. We will re-enable Polygon payments once the migration window closes; until then, Polygon transfers will not be detected by the on-chain verifier and should not be used. If you only hold USDC on Polygon, the simplest route today is to bridge to BNB or Ethereum via a reputable bridge before paying. We track payment-network status in real time on the changelog.
The two-network design is intentional. Every supported rail expands the engineering surface for monitoring, attack-mitigation, and reconciliation. We would rather support two rails reliably than five rails poorly.
BNB Smart Chain — the cheap and fast option
The USDC contract on BNB Smart Chain is at 0x8AC7…eB48 (BscScan). It is the canonical Circle deployment, not a wrapped or bridged variant.
Three properties to know:
- Decimals: 18. One USDC on BSC is represented as
1000000000000000000base units. This is unusual — most USDC deployments use 6 decimals — and traces back to BSC's early ecosystem convention of standardizing on 18-decimal ERC-20s. Wallets and explorers handle the conversion for you, but if you script payments, mind the difference. - Gas: ~$0.15–$0.30. A standard ERC-20 transfer uses ~50,000 gas at typical 3–5 gwei prices, paid in BNB. You'll need a small BNB balance (0.001 BNB is plenty) to send.
- Finality: ~3 seconds. BSC produces a block every ~3 seconds and we treat 15 confirmations (~45 s) as final for subscription crediting.
Ethereum mainnet — the institutional rail
The USDC contract on Ethereum is at 0xA0b8…eB48 (Etherscan). This is the original USDC deployment and the reference implementation Circle attests against.
- Decimals: 6. One USDC is represented as
1000000base units. This is the default across most chains, and the BSC 18-decimal exception above is the outlier. - Gas: ~$2–$15. A transfer uses ~65,000 gas, priced in ETH. Cost varies wildly with network congestion. Plan for the upper end during major resolution events.
- Finality: ~12-second slot, ~13-minute economic finality. Post-Merge Ethereum finalizes via Casper FFG; we credit subscriptions after 32 block confirmations (~6 minutes) which is more than sufficient for the value at stake.
Why decimals differ across chains
If you have only ever interacted with stablecoins through a wallet UI, you've probably never seen the decimal field. It is, however, a real on-chain property of the token contract. The ERC-20 standard lets every token define its own decimals, and Circle's deployment choices reflect the conventions of each ecosystem at deployment time. On Ethereum (2018), 6 decimals was chosen to mirror traditional cents-style accounting. On BSC (2020), the dominant convention was already 18 decimals to match WETH/BNB-pegged assets, so Circle followed suit.
For a copy-trading user paying $299/month, the practical effect is zero: your wallet UI displays "299 USDC" on either chain. For developers reading our API and our on-chain verifier, the difference is one of the few places integration bugs reliably hide. If you script anything, normalize to dollars in your own ledger and only multiply back to base units when constructing a transaction.
Side-by-side: which network is right for you?
| Property | BNB Smart Chain | Ethereum mainnet |
|---|---|---|
| Typical gas cost | ~$0.20 | ~$2–$15 |
| Confirmation time | ~3 s/block | ~12 s/slot |
| Poly Syncer crediting delay | ~45 s (15 conf.) | ~6 min (32 slots) |
| USDC decimals | 18 | 6 |
| Native gas asset | BNB | ETH |
| Best for | Retail, frequent renewals | Institutional treasuries, custody |
| Reorg risk after finality | Negligible | Negligible |
The recommendation for most users is straightforward: pay on BNB Smart Chain. You save 95%+ of the gas cost, the crediting delay is short enough you won't even notice, and the security model is more than sufficient for a $299–$499 monthly transfer. The only cases where Ethereum is preferable are (a) paying from a custody platform that has not approved BSC, (b) paying from a multisig whose signers are most comfortable on Ethereum, or (c) treasury accounting policies that require Ethereum-only flows.
How on-chain verification works
When you initiate a payment, Poly Syncer generates a unique deposit request: an amount, an expiry, and a memo. Our indexer subscribes to Transfer events on the relevant USDC contract and matches incoming transfers against open requests. The first transfer that matches the amount + recipient + within-window arrives, advances through the required confirmations, and credits your subscription. The full request → transfer → credit chain is exposed via the public API and reflected in your billing dashboard at /dashboard/billing.
Three implementation details worth knowing:
- Confirmations are not negotiable. We do not credit on a 1-conf inclusion to defend against shallow reorgs. The wait is always at least the chain's economic-finality threshold.
- Overpayments are credited at face value. If you send $300 instead of $299, you'll be credited for the full month and the extra $1 stays on your subscription as a small credit toward your next renewal. We never auto-refund — refunds would require us to hold a hot wallet, which is the architectural property we go to great lengths to avoid.
- Underpayments do not credit. If you send $298, the system will not partial-credit; you'll need to top up to the exact requested amount before the request expires. The expiry is generous (24 hours) precisely so that bridging or top-up is never rushed.
Common pitfalls (and how to avoid them)
Sending the wrong USDC variant
Historically, some chains had two flavors of USDC simultaneously — the canonical Circle deployment and a bridged variant (often called USDC.e). Sending USDC.e to a contract that only watches canonical USDC is the most expensive single mistake in stablecoin operations. The good news for Poly Syncer users: both supported chains use canonical USDC. There is no USDC.e on either of our rails today, so the variant question simply doesn't arise. Just make sure the contract address on your sending wallet matches the address listed in the network sections above.
Sending from a centralized exchange
Most centralized exchanges support both BSC and Ethereum withdrawals. Two things go wrong:
- Wrong network selection. If you withdraw from Binance and click "Ethereum" instead of "BSC," your USDC arrives at the right address but on the wrong rail. The transfer is real, the funds aren't lost, but our verifier is watching the BSC rail and won't see it.
- Memo / tag confusion. Neither USDC payment rail uses memos or tags. If your exchange asks for one, the field belongs to a different asset; leave it blank.
If a withdrawal goes to the wrong rail, support can usually credit the payment manually after on-chain verification — reach out via the channel listed in your dashboard. We can credit, but we cannot move funds between chains for you, because that would require us to hold a hot bridge inventory.
Forgetting to leave gas in the sending wallet
You need a small native-token balance (BNB on BSC, ETH on Ethereum) to send any ERC-20 transfer. A wallet holding 1,000 USDC and zero native asset cannot send anything. Keep at least $1 of the native gas asset in any wallet you intend to use.
Reusing a one-shot deposit address past its window
We do issue a fresh request per renewal cycle. Sending to last month's request hash after expiry will not credit this month's subscription. The dashboard always shows the active request — use the latest.
Refund policy and why it works the way it does
Poly Syncer does not issue refunds on completed subscription periods. There are two reasons, and both are structural rather than commercial:
- On-chain payments are final. A USDC transfer is irreversible at the protocol layer. Issuing a refund would require us to push USDC back from a custodial outflow address — which would require us to hold a hot wallet at our custody, which is precisely the surface area the rest of our architecture refuses to have.
- Pricing is deliberately transparent. The free view-only tier exists so you can study the leaderboard, inspect any wallet, and validate fit before paying anything. By the time you pay $299, you've already confirmed which wallets you want to follow and what latency budget Pro needs to clear.
If you cancel, your subscription remains active until the end of the period you've already paid for — you don't lose what you paid for, you just don't auto-renew. Manage cancellation from /dashboard/billing. The full policy is in the terms of service.
How payments fit the broader cost picture
The subscription is one line in a stack. Gas to pay the subscription is another. The trading economics of Poly Syncer — per-fill slippage, latency, per-trade gas — are different again, and we cover those line by line in copy trading vs manual. If you're sizing a bankroll, the subscription is rarely the binding constraint — the slippage and time-cost analysis is what determines whether automation pays for itself. The wallets you choose to follow matter even more, which is why we publish our scoring methodology and the wallet evaluation checklist.
Frequently asked questions
Should I pay with USDC on BNB Smart Chain or Ethereum?
For almost every retail user: BNB Smart Chain. Gas is roughly $0.20 versus $2–$15 on Ethereum, finality is faster, and the security model is more than sufficient for a monthly $299–$499 transfer. Choose Ethereum if your custody platform or treasury policy requires it.
Why does Poly Syncer not accept Polygon right now?
Polygon is under maintenance pending finalization of Circle's bridged-to-native USDC migration on our verifier side. Status updates are posted to the changelog. Until it re-enables, bridge to BSC or Ethereum before paying.
What if I send the wrong amount or to the wrong network?
Underpayments don't credit and need to be topped up to the exact amount during the 24-hour request window. Wrong-network transfers usually arrive successfully on a different chain and can be credited manually after verification. Wrong-address transfers are unrecoverable, as with any blockchain payment.
Why are USDC decimals different on BSC vs Ethereum?
BSC convention at the time of Circle's deployment was 18-decimal ERC-20s, matching WETH and other early-ecosystem tokens. Ethereum's USDC was deployed earlier with 6 decimals, mirroring cents-style accounting. Wallets handle the conversion for you; only matters if you're scripting payments directly.