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Opacus, explained
A private balance on Solana, in plain words: what it is, how to try it in a few minutes, and what the world can and cannot see.
What is Opacus?
Opacus is a privacy layer for Solana. You keep a private balance, pay anyone from it and get paid into it, and the world does not watch.
On a public chain every transfer is on display: who sent it, who received it, how much, and everything else those wallets ever did. Opacus changes that for the part that matters. Money comes in with a deposit and goes out with a cash-out, and both are public on Solana like any transfer. Everything in between happens inside the Opacus pool, where nobody can see how much you hold, who you pay, who pays you, or how much.
It runs with the Solana wallet you already have. Your wallet signs one message, and that signature becomes the key to your Opacus account: the same account on any device, with nothing to write down. Your money sits in the pool's program on Solana, and only your account's keys can move your part of it. Every payment is proved on your own device before it is sent.
Try it in a few minutes
The testnet runs on Solana devnet, with test money that is worth nothing, so you can try everything for free.
- Set your wallet to devnet: Phantom, Solflare and Backpack all work.
- Open app.opacus.tech and connect your wallet.
- Sign once to open your Opacus account.
- Get free test money, and deposit some of it into your private balance.
- Pay someone, or send money as a link, and see it arrive in seconds.
The Quickstart walks you through each step.
What works today
Everything below runs on the testnet now.
- A private balance in SOL and in a test dollar (tUSD), opened from one wallet signature.
- Private payments to an Opacus address, to a short name like @ada, or to one of your people by name, each with a note only the payee reads.
- Payment links and gift links: money anyone can claim from a link, into their own balance or out to any wallet; one link that several people each take a share of.
- Requests and QR codes to ask for an amount, and bills split between friends.
- Private swaps from SOL to test dollars and back, without leaving the pool.
- Cash-outs to any Solana wallet, even a brand new one.
- Paying many people at once from a list, never paying anyone twice.
- Short names: claim @yourname, and people pay it in place of your address.
- Receipts, balance proofs and statements: show one payment, show that you hold at least an amount without the figure, or give your accountant a history they can check.
- Pay with Opacus for shops: one line of HTML puts a button on a website.
- The pool in the open: what the pool holds and how much it moves, for anyone to read.
What the world can see
| Move | Public on Solana | Private |
|---|---|---|
| Deposit | your wallet and the amount | what you do with it afterwards |
| Payment inside the pool | that a payment happened | who paid whom, how much, which asset, the note |
| Cash-out | the wallet it goes to and the amount | whose balance it came from |
| Swap | the amounts, the assets and the market | whose swap it was |
| Short name | the name and the address it points to | whose name it is |
| Your balance | nothing | all of it |
The full picture, with what Opacus's own services see, is on What stays private.
Read next
- Quickstart: your first private payment, step by step.
- The testnet: test money, fees and daily limits.
- How Opacus works: the pool, notes and proofs, without the maths.
- Questions: short answers to what people ask most.