Web3 · Product
Crypto Wallet Development
Seed phrases lose users at the door and one lost backup loses the funds forever, so wallet UX is where most on-chain products quietly bleed retention. Crypto wallet development is the engineering practice that builds key management and transaction UX into a non-custodial product. We build account-abstraction smart-account wallets on ERC-4337, with gas sponsorship, social and multisig recovery, session keys, and batched transactions.
- ERC-4337account abstraction standardsmart-account wallets
- Nero ChainAA wallet in productionaa-platform.nerochain.io
- Non-custodialkeys stay with the userno custody of funds
In short
What is Crypto Wallet Development?
Crypto wallet development is an on-chain engineering practice for product teams that builds non-custodial key management and transaction UX. We build account-abstraction smart-account wallets on ERC-4337, with gas sponsorship, social recovery, and session keys. We built an account-abstraction wallet on Nero Chain, live at aa-platform.nerochain.io. Our contract work is engineered for external audit.
What we deliver
Concrete artefacts, not capabilities
- 01
ERC-4337 smart-account wallet with gasless transactions via a paymaster.
- 02
Social and multisig recovery flows that replace single seed-phrase risk.
- 03
Session keys for scoped, time-bound signing without per-action prompts.
- 04
Batched transactions that approve and execute in a single user operation.
- 05
Bundler and paymaster integration with deployment scripts and monitoring.
Key concepts
Key terms, defined
- Account abstraction
- Account abstraction is a design where a smart contract, not an externally owned key, governs an account. On ERC-4337 it lets a wallet define its own signing, recovery, and gas rules, so behaviour like social recovery or sponsored gas lives in code rather than being fixed by the protocol.
- ERC-4337
- ERC-4337 is the Ethereum standard that adds account abstraction without changing the base protocol. Users sign a UserOperation that a bundler submits through a singleton EntryPoint contract. A smart-account wallet implements the standard, enabling paymasters, session keys, and recovery while keeping the account non-custodial.
- Paymaster
- A paymaster is an ERC-4337 contract that pays the gas for a user operation. It lets an application sponsor transactions so a new user transacts without holding the native token, or accepts gas payment in a stablecoin. Sponsorship rules and spending limits are enforced on-chain by the paymaster.
- Session key
- A session key is a scoped, temporary signing key a smart-account wallet authorises for a limited set of actions and a fixed time window. It lets a user approve a session once, then transact without re-signing each action, while the smart account enforces the limits the key was granted.
How we work
Engagement phases
Account model & scope
We map the wallet to the product: which actions need a signature, what recovery the user expects, and whether gas is sponsored, paid in a stablecoin, or paid normally. From that we choose the smart-account implementation and the bundler and paymaster setup. The output is an account model and threat surface the rest of the build is engineered against.
Smart account & recovery
We implement the ERC-4337 smart-account contracts: the validation logic, recovery module, and session-key permissions. Social and multisig recovery replace single seed-phrase risk, so a lost device does not mean lost funds. Contracts are tested against the threat model and engineered for external audit, with every privileged path named before code ships.
Paymaster & UX
We wire the paymaster so the application can sponsor gas or accept it in a token, with on-chain spending limits. The client builds and signs UserOperations, batches approve-and-execute into one step, and submits through the bundler. The result is a flow where a first-time user transacts without first acquiring the native gas token.
Deploy & operate
We deploy the contracts, verify sources on the explorer, and run the bundler and paymaster against the live chain. We monitor paymaster balance, recovery events, and failed user operations, and document every privileged role and limit. The Nero Chain AA wallet runs in production through exactly this path, and we hand over runbooks for in-house operation.
Tech stack
What we build on
- ERC-4337Standard
- SolidityLanguage
- Nero ChainChain
- EntryPointContracts
- BundlerInfrastructure
- PaymasterGas
- FoundryTesting
- viemClient
- ERC-4337Standard
- SolidityLanguage
- Nero ChainChain
- EntryPointContracts
- BundlerInfrastructure
- PaymasterGas
- FoundryTesting
- viemClient
Scope
When this fits and when it doesn't
| This fits when | This doesn't fit when |
|---|---|
| You want an embedded non-custodial wallet where new users transact without first buying gas. | You want a custodial exchange wallet where your company holds and controls user funds. |
| Seed-phrase loss and signing friction are hurting onboarding or retention in your product. | A standard externally owned account wallet already meets the product with no recovery or gas needs. |
| You need scoped session keys or sponsored gas that a standard externally owned account cannot provide. | The primary deliverable is exchange listing, market making, or off-chain treasury operations. |
Related services
Adjacent engagements
- Web3
Smart Contract Development
Solidity, Vyper, and Move contracts engineered for third-party audit, with tests and monitoring.
- Web3
Decentralized Identity & ZKP
Verifiable credentials, DID resolvers, and zero-knowledge selective disclosure. Live Aadhaar eKYC integration, portable across identity systems.
- Product Studio
MVP Development
Zero-to-launch product builds - founder-led scope through first paying users.
Frequently asked questions
A wallet manages signing keys and transaction UX: it holds the keys that authorise on-chain actions and presents recovery, gas, and approval flows to the user. Decentralized identity manages credentials and verifiable claims about who someone is. They sit next to each other, since a wallet can hold identity credentials, but wallet work is key management and transaction signing, not credential issuance or verification.
Account abstraction moves account rules from the protocol into a smart contract, so the wallet defines its own behaviour. A user can recover access through social or multisig recovery instead of a single seed phrase, transact without holding the native gas token when a paymaster sponsors gas, and approve a session once rather than signing every action. The account stays non-custodial throughout.
Yes. The user controls the smart account through their own signing keys, and no third party can move funds on their behalf. Account abstraction changes how signing and recovery work, not who holds the funds. Social recovery distributes the ability to restore access across guardians the user chooses, but neither the application nor we ever take custody of the assets in the account.
We engineer the smart-account contracts for external audit and run an internal audit pass against the threat model, but the external audit is a separate firm, as it should be. We name every privileged path before code ships and test against the threat model. Our smart-contract record includes a contract suite cleared across four Hacken audit rounds, and we coordinate the wallet audit with the firm you choose.
Often yes, depending on how the current wallet is built. We can add an ERC-4337 smart-account layer alongside an existing externally owned account, introduce a paymaster for sponsored gas, or add session keys and recovery without replacing the whole product. We read the current architecture, signing flow, and key handling first, then scope the smallest change that delivers the account-abstraction features you need.
Last reviewed · Reviewed by Metaborong engineering team
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