Mobile wallet options for Neptune Cash

General
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Cryptocurrency that is hard to use is more likely to stay niche. For most people, the wallet is their experience of a cryptocurrency, and today that wallet often runs on a phone.

Neptune Cash has a working desktop wallet for Windows, Linux and macOS, but currently no working mobile wallet. The only one, a community-built Android app, is not compatible with hardfork delta and can’t create transactions.

To explore the options, I built a proof-of-concept wallet, Neptune Vault, that runs as a desktop app, a web app (PWA) and an Android app, largely with the help of AI tools. It works, but it isn’t mature enough for real use. Building it suggested that the main obstacle to a mobile wallet isn’t necessarily technical. It’s ownership and bureaucracy: who publishes the app, under which legal entity, and who maintains it?

1. Why not a web app?

A progressive web app (PWA) is a website that can be installed to the home screen and works on any device. It would be the easiest truly cross-platform option, but it has two problems:

  • Trust: The browser downloads and runs whatever code the server delivers, every time the app loads. Users have no easy way to verify that code:

    • There’s no signed, fixed release. The code can change at any moment without users noticing.
    • Even if the wallet is open source, nothing guarantees the server delivers the same code that’s on GitHub.
    • A compromised server could even deliver malicious code to selected users only, making the attack very hard to detect.

    With a native app, every release is signed by the developer, users install updates explicitly, and the installed version stays the same until they update. For a wallet holding funds, that difference matters. Neptune Vault reduces the risk by never updating silently and by publishing file hashes for each release, but users still have to trust the host.

  • Performance: Sending requires heavy cryptography. The wallet’s Rust code can be compiled either to native ARM64 machine code for an Android app or to WebAssembly (wasm) for a PWA. In testing on a Samsung Galaxy S24, a typical send took about 16 seconds with the native build and roughly six times longer with the wasm build in the same phone’s browser.

Newer technologies may eventually solve the trust issue of web applications. Isolated Web Apps (IWAs) package and sign a web app like a native one. WAICT, a W3C-backed effort by browser vendors and others, aims to guarantee that every user gets the same, publicly logged code. Neither is ready yet, especially on mobile. So in practice, a mobile wallet needs to be a native app.

2. What any mobile wallet needs

  • A remote node. Phones can’t run a full node, so the wallet connects to a node to sync and send transactions. Keys and proving stay on the phone. Someone needs to run reliable public nodes, and users should be able to use their own. To begin with, a mobile wallet could use the same public node as the desktop Neptune Wallet.
  • A reasonably capable phone. Proving a send needs about 1 GB of free memory, so phones with 4 GB of RAM or less may struggle. 16 seconds is the result on a 2024 flagship; older and mid-range phones will be slower. This should improve fairly quickly as phones and the prover get faster each year.

3. Android and iOS

  • Android: Apps can be sideloaded, i.e. installed from GitHub or a website. Google is introducing developer verification for apps distributed outside Google Play, starting in selected countries in 2026 and expanding globally in 2027. This makes sideloading more complicated for ordinary users, although it remains possible.
  • iOS: The App Store is the normal distribution route, and it’s considerably more restrictive.

4. App stores

Both Apple and Google require cryptocurrency wallets to be published from an organization account. This applies to self-custody wallets too. An individual developer account isn’t enough. You need:

  • a registered legal entity (company, association or foundation)
  • organization verification, including a D-U-N-S number (a free company identifier the stores use to confirm the organization exists)
  • a website on the organization’s own domain
  • a person authorized to sign agreements for the organization

Legal questions are worth keeping in mind too, though they shouldn’t be overstated. A self-custody wallet doesn’t hold anyone’s funds, which puts it in a much better position than a custodial service. Cases against wallet developers, such as Samourai Wallet in the US, have involved additional services like fee-earning mixing.

5. Maintenance and funding

Store fees are small. The real cost, in time, effort and money, is elsewhere:

  • updating the wallet before every hardfork
  • keeping up with Apple and Google policy changes
  • store reviews and user support
  • running public nodes
  • a security review before release
  • for an organization account, the ongoing administration: bookkeeping, annual filings and keeping store verification up to date

Work like this shouldn’t depend on one person. A wallet is best owned by an organization that outlives individual contributors, so people can join and leave without the app being abandoned. Money could come from donations or ecosystem funding, and time and effort from community contributors.

6. Options

  1. Update the existing Android wallet for hardfork delta. Quickest fix, but Android only, and its developer no longer appears to be maintaining it. Its Google Play listing is also under a third-party company account, outside the project’s control, so someone else would have to take over both the code and the listing. Even if it’s revived, it would be better placed under an organization with direct ownership.
  2. Sideloaded Android app. Works today without an app store listing. From 2027, Google’s developer verification adds friction, but no organization is needed. No iOS, however.
  3. An existing entity publishes to both stores, such as a company or organization supportive of Neptune. Cleanest, if one exists and is willing.
  4. Commission an established developer to build a Neptune wallet, or to add Neptune to an existing multi-coin wallet such as Stack Wallet or Cake Wallet. They already have organization accounts, app store experience and maintenance processes. Firo’s Campfire wallet is an example: it was built and published by Cypher Stack, with outside funding. This needs funding, and Neptune’s heavy client-side proving may make integration harder than for most coins.
  5. A new nonprofit association set up to publish wallets. More work up front, but not tied to one person.
  6. A web app as a stopgap, clearly marked experimental and for small amounts only.
  7. Wait a few years for IWAs, WAICT and similar technologies to mature in mobile browsers. A trustworthy web wallet would avoid app stores entirely, but Neptune would have no mobile wallet in the meantime.
  8. Something else? Ideas I haven’t considered are welcome.

How others did it

  • Monero: Cake Wallet (iOS and Android) is published by a company, Cake Labs. Monerujo is an Android-only wallet on Google Play and F-Droid that syncs through remote nodes.
  • Zcash: The Zashi wallet was built by the Electric Coin Company. In 2026 the team left after a governance dispute, formed a new company, and renamed the wallet Zodl. Ownership questions don’t end once an owner is found.
  • Firo: Campfire, a Firo-only wallet for mobile and desktop, is developed by Cypher Stack, a company that also makes the multi-coin Stack Wallet. Initial funding came from a third party, and Firo’s community fund supports ongoing work.
  • Dash: The official Dash Wallet is built by Dash Core Group. Android has been available since 2014, but Apple rejected the iOS version in 2016 and only approved it in 2017 after a formal appeal.
  • PIVX: PIVX got its native iOS wallet into the App Store in 2019 after about a year of trying. Today its main wallet, MyPIVXWallet, is a non-custodial web wallet that can also be installed as a PWA, built by PIVX Labs, a small DAO.
  • Beam and Zano: Both official mobile wallets are published by the projects’ own companies, Beam Development Limited and Zano Limited.
  • Grin: The closest match to Neptune: no company, only volunteers. Its mobile wallets come from individual developers, and getting onto iOS has been a recurring struggle. One developer even released a testnet-only iOS app to avoid Apple’s restrictions on individual accounts.

The pattern: wallets in the app stores are generally published by companies or other organizations, and getting a privacy coin wallet approved has taken persistence. Projects without a company, like Grin and Neptune, face exactly the questions raised in this post.

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