Why Relayers?

Why Relayers?

The relayer is a critical component for maintaining privacy. Without it, withdrawals would leak information about the recipient.

The Problem: Gas Payment

On Solana, every transaction requires the fee payer to:

1. Sign the transaction
2. Pay SOL for transaction fees

If you withdraw directly, your recipient address:

• Appears as the transaction signer
• Must have SOL to pay fees
• Creates an on-chain link between the withdrawal and your address

This defeats the purpose of private transfers - anyone can see that the withdrawal recipient signed the transaction.

The Solution: Relayer

A relayer is a service that:

1. Receives your signed withdrawal proof
2. Submits the transaction on your behalf
3. Pays the transaction fees
4. Receives a small fee from the withdrawn amount

Now the transaction shows:

• Signer: Relayer’s address (not yours)
• Fee Payer: Relayer (not you)
• Recipient: Your address (just receives tokens, no signature required)

Privacy Guarantees

With Relayer	Without Relayer
Recipient appears as just a token receiver	Recipient appears as transaction signer
No SOL needed in recipient wallet	SOL required to pay fees
No on-chain link to your signing key	Direct link to your key

How the Relayer Works

1. You generate a ZK proof proving you can withdraw
2. You specify the recipient address in the proof
3. Relayer verifies the proof is valid
4. Relayer submits the transaction, paying gas
5. Program verifies the proof on-chain
6. Tokens transfer to your specified recipient
7. Relayer fee is deducted from withdrawn amount

Trust Model

Note

The relayer is non-custodial. It cannot:

• Steal your funds (proof specifies recipient)
• Censor you (other relayers can be used)
• See your nullifier or secret

The relayer CAN:

• See your recipient address
• Choose not to relay (but you can use another relayer)
• Charge a fee

Relayer Fees

The relayer deducts a fee from the withdrawn amount to cover:

• Solana transaction fees
• Service operation costs
• Profit margin

See the Fee Structure page for current fee rates.

Using the Relayer API

The Turbine.cash relayer exposes two endpoints:

Endpoint	Purpose
POST /relay	Withdraw tokens to any address
POST /relay_swap	Withdraw and swap via Jupiter

See the API Reference for detailed documentation.

Next Steps

• Learn about OFAC Compliance
• Implement a Withdrawal
• Implement Withdraw with Swap