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lock-keyholeRailgun Private Sends: Privacy and Fee Structure

This page explains what Railgun Private Sends are, their level of privacy, and the internal Railgun fee structure that is not under LibertySwap control but the blockchain networks and Railgun relayers

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What are Railgun Private Sends?

Railgun has three forms of transactions inside of shielded balances with different levels of privacy: Private Sends, Private Swap, and Private DeFi.

Private Sends are transfers from one shielded address to another shielded address inside Railgun with the highest level of privacy: complete privacy. This is the simplest and strongest privacy flow in Railgun.

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Private Sends? From an 0zk address to another 0zk address

Private Sends happen entirely inside Railgun’s privacy system.

  • No public blockchain transaction is created.

  • No miner or validator interaction is required.

  • No gas is paid by the user.

Because nothing is written publicly on chain, the cost is minimal and predictable.

LibertySwap is designed to preserve this strong privacy model.

Our swap flows are built so that:

  • Funds remain shielded as long as possible.

  • Swaps originate from shielded balances.

  • Users benefit from Railgun’s strongest anonymity guarantees.

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Railgun Private Sends Fee Structure and Estimation

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Railgun 0zk → 0zk Transfer Fees (Ethereum Example)

For a Railgun 0zk → 0zk private transfer on Ethereum, the fee you pay is essentially independent of the value transferred. Whether you send $10 or $100,000, the underlying transaction cost remains roughly the same. This is because the fee is driven by computation and network gas price, not the dollar amount of the transfer.

What the Fee Depends On

zk-SNARK Transaction Gas:

  • Railgun uses zero-knowledge proofs for private transfers.

  • The gas consumed by proof verification and shielded state updates is almost fixed for a single private send.

Underlying Chain Gas Price (Real Estimate)

  • Current Ethereum gas prices are extremely low, around 0.03–0.5 Gwei at the moment.

  • With Ether trading around $3,200 per ETH, this results in minimal fees even for complex contract interactions.

Relayer Premium

  • Railgun relayers add a small premium on gas, usually around 10% over the base gas cost.

  • This premium can vary by relayer and market conditions.

What the Fee Does NOT Depend On

Transfer Amount

  • The fee is not proportional to how much value you move.

  • Railgun does not charge per dollar moved for private transfers.

Percentage-Based Protocol Fees

  • Private 0zk → 0zk transfers do not incur percentage fees like shielding/unshielding does.

Practical Ethereum Cost Estimate (Right Now) Assuming:

  • An estimated zk-SNARK Railgun transaction uses a substantial amount of gas compared to a simple transfer (eg hundreds of thousands of gas units),

  • Gas price ~0.1–0.5 Gwei as seen on Ethereum today,

  • Ether price around $3,200 per ETH,

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Estimated Railgun 0zk → 0zk Fee: Approximately $0.50 to $2.00 total, including relayer premium.

This is much lower than what many users remember from earlier years, thanks to recent upgrades that have compressed gas prices and lower on-chain congestion.

When Fees Can Change

Fees may be higher if:

  • You include multiple assets in one private transfer.

  • Ethereum gas prices rise due to higher demand.

  • You choose a relayer charging a higher premium.

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