Every account screen you put between a customer and a working product costs you users. Analytics from connected-hardware launches consistently show a double-digit percentage of buyers abandoning setup at the registration step — people who already paid for the device and then walked away because they did not want to invent another password while standing in their kitchen. The account has to earn its place, and once you decide it does, the design decisions that follow are harder than they look.

Does the Product Need an Account at All?

Accounts are genuinely required when the product syncs data across devices, when a user must reach it from outside the home network, when you sell a subscription or a consumable refill, or when you have a regulatory duty to identify who did what. Accounts are not required for a Bluetooth device that pairs directly with one phone and stores its settings locally.

That distinction maps closely onto the architecture split in local control versus cloud control. A local-first product can defer accounts entirely, and a great many should. If the answer is genuinely no cloud, no account, you have removed an entire backend, a password reset flow, a privacy policy obligation, and a support category in one decision.

Guest Mode as the Middle Path

The strongest pattern for a hardware companion app is guest first. The user opens the app, pairs the device, and it works. Somewhere later — when they want a second phone, cloud history, or a firmware update notification — the app offers to create an account and silently migrates the local data into it. Conversion rates for that deferred prompt run far above a hard gate at first launch, and the setup experience stays as short as the one described in product-to-app onboarding and pairing.

Choosing Sign-In Methods

  • Email and password — universal, works everywhere, and generates the largest share of your support tickets. If you offer it, you own password reset, breach response, and hashing done correctly.
  • Sign in with Apple and Google — one tap, no password to lose. Apple's App Store review rules require Sign in with Apple as an option whenever you offer another third-party login, so budget for it as mandatory rather than optional if you plan to ship on iOS.
  • Magic links and one-time codes — no password at all, delivered by email. Excellent conversion, with the caveat that a link opening in a different browser context needs careful handling and email delivery must be reliable.
  • Passkeys — biometric credentials tied to the device and synced through the platform keychain. The best security and usability combination currently available, and worth building alongside a fallback rather than as the only path.

For a consumer hardware product, a practical default is passkeys or platform sign-in as the primary route, with a one-time email code as the recovery path, and no password field anywhere. For a B2B or field-serviced product you will usually also need username-based credentials that an IT department can manage, which is one of the reasons a separate service application often appears, as discussed in user app and technician app.

The Genuinely Hard Part: Device Sharing

Software accounts assume one user owns their data. Hardware breaks that assumption immediately. A thermostat belongs to a household. A shared vehicle accessory has a primary driver and occasional users. A rental unit changes hands entirely.

Model this explicitly rather than discovering it in support tickets. You need at minimum an owner role with full control including the ability to remove other users, an invited-member role with day-to-day control but no ability to unpair or factory reset, and a guest role with time-limited or scope-limited access. You also need three flows people rarely plan for:

  1. Ownership transfer when the device is sold or gifted, without the previous owner retaining cloud access to the new owner's data.
  2. Factory reset from the hardware itself, so a device bought secondhand can be claimed even when the original account is unreachable. This is where a stolen or resold device becomes a security question, covered in IoT security for connected products.
  3. Household separation, when two members who shared a device stop sharing a home.

If any user might be under thirteen — connected toys, kids' wearables, learning devices — the account design also inherits verifiable parental consent obligations under COPPA, which reshapes registration rather than merely adding a checkbox.

Account Deletion Is a Shipping Requirement

Both major stores now enforce this. If your app supports account creation, Apple requires account deletion to be initiated from inside the app, not by emailing support. Google Play requires a deletion request path plus a web-accessible route for users who have uninstalled. State privacy laws including the California Consumer Privacy Act add deletion and disclosure duties on top.

In practice you need a deletion endpoint that removes personal data, unbinds devices, cancels subscriptions, and returns a confirmation, plus a documented retention policy for anything you keep for legal or safety reasons. Apps get rejected at review for missing this, so build it before submission rather than after — one of the recurring surprises in publishing to the app stores. What data you may retain, and what disclosures you owe, follows the framework in privacy compliance for connected product data.

What It Costs

A managed identity service such as Auth0, Firebase Authentication, or Cognito covers sign-in, tokens, and password reset for a few hundred dollars a month at consumer scale, and integrating one runs roughly $8,000 to $18,000 of app and backend work. Adding multi-user device sharing, roles, invitations, and ownership transfer typically doubles that. Building identity from scratch is almost never justified for a hardware venture and introduces exactly the security surface you are least equipped to defend.

Designing the Account Layer

Projects House designs companion-app account and device-sharing models for US hardware ventures, including the ownership, reset, and deletion flows the stores check at review. Describe your product and who shares it through our contact form.