> For the complete documentation index, see [llms.txt](https://mixfun.gitbook.io/mixfun/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://mixfun.gitbook.io/mixfun/flows/private-send.md). # Private Send > Mix SOL through zero-knowledge proofs for untraceable transfers. {% hint style="danger" %} **Your note is the only way to withdraw this deposit.** If you lose it, the funds cannot be recovered. Treat the note like a private key and back it up before sharing or closing the tab. {% endhint %} ## What is a Private Send? Private Send is a note-based privacy mixer for Solana. You deposit a fixed amount of SOL into a shared pool, receive a short encrypted note, and share that note with whoever should receive the funds. They withdraw the matching amount from the pool into a wallet of their choice. On-chain, the deposit and the withdrawal look like independent events. There is no public link between them. The pool's anonymity set, the number of active deposits sitting alongside yours, determines how hard the link is to guess. MixFun does not hold your funds. The pool is a Solana program account. Only a valid note, combined with a zero-knowledge proof, can withdraw from it. **Core Features:** * **Privacy via anonymity set.** The larger the pool, the stronger the unlinkability. * **Non-custodial.** The pool is on-chain; only a signed proof can withdraw. * **Fixed denominations.** 0.1 SOL, 1 SOL, 10 SOL, or 100 SOL per deposit. * **Optional relayer.** Withdraw into a freshly created wallet without paying gas yourself. * **Supported wallet.** Phantom. ## How it works 1. **Choose a pool.** Pools are grouped by denomination. Larger pools have more past deposits mixed together, which strengthens the link between your deposit and the eventual withdrawal. See [Anonymity sets](/mixfun/concepts/anonymity-sets.md) for the classification we apply. 2. **Deposit.** Your wallet signs a deposit for the chosen denomination. MixFun returns a short note encoding a spend secret plus a nullifier. 3. **Save the note.** The note is the only thing that can withdraw those funds. If you lose this note, your funds cannot be recovered. Treat it like a private key. See [Back up a note](/mixfun/guides/back-up-a-note.md). 4. **Share the note (optional).** Send the note to the recipient through any channel you trust: direct message, encrypted email, or a MixFun share link. Share links have a configurable maximum number of claims (default 1) and an expiry. 5. **Withdraw.** The recipient uses the note to generate a zero-knowledge proof in their browser, then submits a withdrawal transaction. The note is consumed on withdrawal and cannot be reused. 6. **Use a relayer (optional).** If the recipient wants to withdraw into a wallet that has never been funded, MixFun's relayer can submit the transaction for them. The relayer pays the Solana gas so the fresh wallet stays unlinked to any prior activity. See [Use the relayer](/mixfun/guides/use-the-relayer.md). ## Who it's for ### Ideal for * Paying a collaborator without revealing your main wallet * Sending SOL to yourself across wallets without leaving a trail * Splitting a balance into smaller withdrawals over time * Receiving SOL into a wallet you want to keep unlinked ### Not recommended for * Hiding the deposit amount. Pool denominations are public. * Amounts smaller than 0.1 SOL. That is the minimum denomination. * Hiding that you interacted with MixFun. Both events are on-chain. * Long-term storage. MixFun is a transit layer. ## Summary at a Glance * **Privacy Level:** High (depends on anonymity set of the chosen pool). * **Speed:** Deposit is one transaction. Withdrawal is one transaction, or a relayer job that finishes in a few seconds. * **Fee:** 0.1% of the deposit denomination (10 basis points). Optional relayer fee on withdrawal. * **Best For:** Private SOL transfers with a shared note. * **Custody:** Non-custodial. The pool is a Solana program account. Only a valid note plus a ZK proof can withdraw. --- # Agent Instructions This documentation is published with GitBook. GitBook is the documentation platform designed so that both humans and AI agents can read, navigate, and reason over technical content effectively. Learn more at gitbook.com. ## Querying This Documentation If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question. Perform an HTTP GET request on the current page URL with the `ask` query parameter, and the optional `goal` query parameter: ``` GET https://mixfun.gitbook.io/mixfun/flows/private-send.md?ask=&goal= ``` `ask` is the immediate question: it should be specific, self-contained, and written in natural language. `goal` is optional and describes the broader end goal you are ultimately trying to accomplish on behalf of the user. GitBook uses it to tailor the answer towards what is most useful for that goal. The response will contain a direct answer to the question and relevant excerpts and sources from the documentation. Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.