What is Qietr?
Qietr is a zero-knowledge privacy layer for HTTP 402 micropayments on Solana.
Understanding x402 and Qietr
x402 — The HTTP 402 Payment Protocol
Developed by Coinbase and Cloudflare, x402 is a standard for web micropayments. When an HTTP server responds with 402 Payment Required, the client pays a specified amount and retries the request with a payment header.
// Standard x402 — Alice's wallet → Bob's address
// Everyone can see Alice paid Bob
Problem: Every payment is tracked. Merchants can profile customers. Competitors can analyze usage. No financial privacy.
Qietr — Shielded Layer for x402
Qietr adds zero-knowledge privacy to x402 payments. Funds go through a shielded pool, breaking the link between depositor and payer.
// Qietr — Shielded Pool → Bob's address
// Bob gets paid, can't identify who paid
The sender proves eligibility via a ZK proof without revealing which deposit is theirs, their wallet address, or their transaction history.
How to use
What you need
- Phantom, Solflare, or any Solana wallet
- USDC on Solana (devnet for testing)
- Small amount of SOL for gas
Step 1: Connect wallet
Open the app and connect your Solana wallet.
Step 2: Deposit
Choose a fixed denomination tier: 0.1, 1, 10, or 100 USDC. Deposit into the shielded pool and save your encrypted note.
Step 3: Pay
Load your note, enter a recipient address (or x402 endpoint URL), choose an amount, and generate a zero-knowledge proof. The recipient receives USDC with no link to your deposit.
Deposit vs spending
Deposits are in fixed denominations for better privacy — your anonymity set is every other deposit of the same tier. Spending is flexible: pay any amount up to your balance and make multiple payments from one deposit. Note that a partial payment creates an on-chain “change” note linkable to that spend; to stay in the full anonymity set, spend whole denominations or re-deposit change.
Use cases
AI agent payments
Autonomous agents pay for API access, compute, and subscriptions without revealing their identity or being tracked by competitors.
Developer API usage
Pay for API calls without usage profiling. Protect business logic and prevent competitors from analyzing your usage patterns.
Content access
Pay for articles, datasets, and premium content without user profiling or tracking across sites.