Private payments on Arbitrum
Send ETH and USDC privately on Arbitrum. Shield once, then pay any address, swap or bridge with zero-knowledge proofs: no custody, and the relayer pays gas. Arbitrum One is an Ethereum layer 2 rollup, with ETH for gas and USDC as its main stablecoin.
What you can do on Arbitrum
- Shield ETH and USDC from your wallet into a private balance. This is the only step that shows your address on-chain.
- Send privately to any address on Arbitrum. The recipient gets a normal transfer from the pool; nothing on-chain points back to your wallet.
- Swap privately between ETH and USDC through Uniswap V3, with the output going straight back into your private balance.
- Bridge privately to other chains through NEAR Intents, from the
arb_eth,arb_usdcpools.
Pools, fees and minimums
| Pool | Min deposit | Min send, swap or bridge | Flat fee |
|---|---|---|---|
| ETH | 0.001 ETH | 0.001 ETH | 0.00015 ETH |
| USDC | 3 USDC | 2 USDC | 0.5 USDC |
Every private spend pays the flat fee plus 0.35% of the amount, deducted from the amount. Shielding has no Blackpool fee. Bridges add the solver's own quote, which the app shows before you confirm.
How it stays private
- Your device builds a zero-knowledge proof that you own funds in the pool, without saying which deposit they came from.
- A relayer submits the transaction and pays the gas, so your wallet never signs or pays for a private spend.
- The recipient, the amount and the fee are fixed inside the proof, so nobody in between can change them.
- Your keys come from one wallet signature and stay on your device; the server never sees them. See the security model.
Get started
In the browser: open the app, connect a wallet, choose Arbitrum in the network menu, sign once and shield. After that, use Send privately, Swap or Private bridge.
From a terminal or an AI agent: the Blackpool CLI does the same with JSON output:
npm i -g @blackpool/cli
blackpool deposit 0.01 --chain arbitrum
blackpool send 0xRECIPIENT 10 --pool usdc --chain arbitrumPrivate bridges from Arbitrum reach Robinhood Chain, Base, Ethereum, BNB Chain and Solana through NEAR Intents.
Questions
Can people see who I paid on Arbitrum?
They can see that funds went into the Blackpool pool and that a payment came out of it, but not which deposit paid which recipient. The deposit is a public transaction; the link between it and your later payments is what the zero-knowledge proof hides.
Do I need ETH for gas to send privately?
Only to shield, because that transaction comes from your own wallet. After that the relayer pays the gas for every private send, swap and bridge, and its fee is taken from the amount you move.
Is Blackpool custodial?
No. Funds sit in the pool contract and only a proof made with your keys can spend them. The relayer can submit a transaction or decline to, but it cannot change the recipient or the amount, because both are fixed inside the proof.
What does a private send on Arbitrum cost?
The pool's flat fee plus 0.35% of the amount, taken from the amount. Sending 10 USDC costs 0.535 USDC, so the recipient gets 9.465 USDC. Shielding has no Blackpool fee, only network gas.
The pool contracts have not had an external audit yet, and each pool's admin is a 2-of-3 multisig that can pause or upgrade it but cannot move funds. Size your balances accordingly.
Other chains
Guides: how to send crypto without exposing your wallet · private payments for AI agents.