Custodial or non-custodial — which should we build?

Non-custodial wallets leave keys with users, which reduces your liability but makes recovery harder. Custodial models are simpler for users but may require licensing in some jurisdictions. Token, securities and money-transmission rules vary by jurisdiction, and those questions are yours to settle with your legal advisers. We explain the technical trade-offs and build the model you and your counsel settle on.

How do users recover a lost wallet?

Options include encrypted cloud backups, social recovery through trusted guardians with smart accounts, and MPC designs where no single device holds the whole key. Each balances convenience against risk differently. We recommend an approach for your audience and test the recovery flow as hard as the happy path.

Can you add a wallet to our existing app?

Yes. Embedded wallet SDKs or a custom smart-account integration can give existing users a wallet behind their current login, with no seed phrase on day one. We review your app’s architecture and security posture first so the wallet does not inherit weaknesses from elsewhere.

Will our wallet include trading or swaps?

We can integrate third-party swap or on-ramp providers if your legal advisers approve it, but we do not offer investment guidance and the app should not either. Features that move or exchange value can carry money-transmission obligations, so that decision rests with you and your counsel.

Can the wallet work with hardware wallets like Ledger or Trezor?

Yes, for users who want their keys on a separate device. We can support connecting hardware wallets over USB or Bluetooth where the platform allows it, so the app prepares transactions and the device signs them. It adds testing across device models and firmware versions, and the signing screens still need to explain each request clearly, because hardware wallets often display very little detail on their own.

How do you protect users from phishing and malicious approvals?

Through several layers. Signing screens decode each request and show its likely effect, such as which tokens leave the wallet. Simulation catches surprises before signing, and unlimited token approvals trigger a clear warning. We can check addresses and sites against known threat lists, show where a request came from, and let users review and revoke past approvals. No wallet can stop every scam, but these measures catch many common ones.

Blockchain & Web3 · Wallet development

Wallets where key security comes first

We build crypto wallets and embedded wallet features for web and mobile, with careful key management, recovery options people can actually use, and signing screens that make every transaction understandable.

Custody model options
Secure key storage
Smart account features

Start your project How we work

Overview

What building a wallet really involves

Wallet development is security engineering with a consumer interface on top. The wallet must generate and protect keys, recover access when a device is lost, show balances and history across networks, and present signing requests in a way that helps users spot danger. Each of those jobs has failure modes that cost people real money, so the design starts with a threat model rather than with screens.

The central choice is custody. A non-custodial wallet leaves keys with the user, which limits your liability but makes recovery the user’s responsibility. A custodial model holds keys for users, simplifies recovery and carries heavier regulatory weight. Middle paths, such as multi-party computation or smart accounts with guardians, spread control. Each has different legal implications, which your advisers should settle before we lock the architecture.

A good wallet earns trust quietly. Keys never leave secure hardware unprotected, recovery is tested by real people, signing screens translate contract calls into plain language, and suspicious requests trigger clear warnings. Security testing runs throughout the build, and we recommend an independent third-party audit or penetration test before any public release.

Who it’s for

Built for teams like yours

01
Apps embedding a wallet
Products that want users to hold tokens, tickets or credentials inside the app, without sending them to install and manage a separate crypto wallet first.
02
Teams launching a standalone wallet
Companies building a dedicated wallet for a specific network, community or use case, who need native mobile quality and a security model they can defend.
03
Organizations managing shared funds
Teams that need multi-signature or policy-controlled wallets for treasury operations, with approval rules, spending limits and a clear record of who authorized each individual transaction.

Why it matters

The hardest part is the keys

A wallet’s real job is protecting keys and helping people avoid signing something harmful. We design around threat models: where keys live, how they are backed up, what happens when a phone is lost, and how a user can tell a legitimate request from a phishing attempt. Interface polish matters, but only after those questions are answered.

Custody choices also carry regulatory weight, and the rules vary by jurisdiction. We flag those decisions early so you and your legal advisers can settle them before the design is locked.

Every engagement includes

Threat modelingkey storage, recovery and phishing risks mapped before any code is written.
Custody decision recordthe chosen model and its trade-offs documented for your legal advisers.
Native or web buildSwift, Kotlin, React Native or web, depending on where users need the wallet.
Security testingcode review, penetration testing and an independent audit recommended before release.
App store readinesssubmissions prepared with platform crypto policies in mind.
Handover & caredocumentation, incident runbooks and an optional maintenance plan.

Features

Wallet capabilities

01
Custody model options
Self-custody, embedded wallets or MPC-based designs, chosen against your users and regulatory position.
02
Secure key storage
Keys held in iOS Secure Enclave or Android Keystore, never in plain storage or logs.
03
Smart account features
ERC-4337 accounts enabling social recovery, spending limits, batched actions and sponsored fees.
04
Readable signing
Decoded transactions and EIP-712 messages shown in plain language, with warnings for risky approvals.
05
Multi-chain balances
Token and NFT balances across supported networks, refreshed through reliable indexing services.
06
WalletConnect support
Secure connections to third-party DApps with clear session management and easy revocation.

In practice

Wallet features we commonly build

Embedded wallets with familiar sign-in
Wallets created automatically when a user signs in with email or a passkey, so newcomers can hold assets right away and still export their keys later if they ever choose to.
Smart accounts with guardians
Account-abstraction wallets where trusted guardians or secondary devices can help restore access, with spending limits, session keys for games or apps, and fee sponsorship configured by the app that issues them.
Multi-signature team treasuries
Wallets requiring approval from several named signers before funds move, with configurable thresholds, a clear queue of pending transactions, and alerts whenever a new request is waiting for someone’s review.
Transaction simulation and warnings
Previewing what a transaction will actually do before anyone signs, such as balance changes or unlimited token approvals, and warning users when a request matches known malicious patterns or flagged addresses.

Process

How we work

1
Threat model
We map where keys live, who could attack them, and what happens on device loss, phishing or compromised servers. The model drives every later design decision and is written down.
2
Custody architecture
We document the custody approach, key generation, backup and recovery design, along with the legal questions each choice raises, so you and your advisers can approve it before development starts.
3
Secure core
We build key management on platform secure storage such as the iOS Secure Enclave and Android Keystore, keeping signing isolated from the interface and covered by focused, security-specific tests on real devices.
4
Signing experience
We design signing screens that decode contract calls into plain language, simulate the result and warn on risky approvals, then test them with real users for clarity when they feel rushed.
5
Testing & release
Code review and penetration testing run before release, and we recommend an independent audit. We then prepare app store submissions and incident runbooks covering lost devices, suspected compromise and urgent key rotation.

Deliverables

What you receive

Written threat model and risk register
Custody architecture and recovery design
Key management module on secure hardware
Plain-language signing and simulation screens
iOS, Android or web wallet application
Penetration test findings and fix log
Incident and recovery runbooks

Tools & methods

Mobile & web

Swift
Kotlin
React Native
TypeScript
React

Key security

Secure Enclave
Android Keystore
Passkeys
MPC libraries
Hardware wallet support

Chain access

WalletConnect
ERC-4337
Safe
viem
Tenderly simulation

FAQ

Frequently asked questions

Anything else about Wallet development? Ask us directly.

Non-custodial wallets leave keys with users, which reduces your liability but makes recovery harder. Custodial models are simpler for users but may require licensing in some jurisdictions. Token, securities and money-transmission rules vary by jurisdiction, and those questions are yours to settle with your legal advisers. We explain the technical trade-offs and build the model you and your counsel settle on.
Yes, for users who want their keys on a separate device. We can support connecting hardware wallets over USB or Bluetooth where the platform allows it, so the app prepares transactions and the device signs them. It adds testing across device models and firmware versions, and the signing screens still need to explain each request clearly, because hardware wallets often display very little detail on their own.
Through several layers. Signing screens decode each request and show its likely effect, such as which tokens leave the wallet. Simulation catches surprises before signing, and unlimited token approvals trigger a clear warning. We can check addresses and sites against known threat lists, show where a request came from, and let users review and revoke past approvals. No wallet can stop every scam, but these measures catch many common ones.

Let’s work together

Have a project in mind?

Book a strategy call and we’ll show you exactly how to turn your goals into a system that generates consistent results.

Book a strategy call All services

Wallets where key security comes first

Custody model options

Secure key storage

Smart account features

Readable signing

Multi-chain balances

WalletConnect support

Embedded wallets with familiar sign-in

Smart accounts with guardians

Multi-signature team treasuries

Transaction simulation and warnings

Threat model

Custody architecture

Secure core

Signing experience

Testing & release

01Custodial or non-custodial — which should we build?

02How do users recover a lost wallet?

03Can you add a wallet to our existing app?

04Will our wallet include trading or swaps?

05Can the wallet work with hardware wallets like Ledger or Trezor?

06How do you protect users from phishing and malicious approvals?

Have a project in mind?