Blockchain & Web3

Crypto Wallets

Key handling, transaction signing, and the screens a person uses to send, receive, and review assets.

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Delivery focus

Built to move from idea to production.

Key handling, transaction signing, and the screens a person uses to send, receive, and review assets. The work sits inside Blockchain & Web3 and is scoped, built, reviewed, and handed over as one engagement.

Clear product and technical roadmap

Scalable implementation standards

Launch support and measurable outcomes

Scope

ClickMasters builds crypto wallet solutions for B2B companies across the USA, Europe, Canada, and Australia. Custodial wallets for exchanges and financial platforms secure key management with HSM and MPC. Non-custodial embedded wallets using Privy or Alchemy Account Kit users own their keys without seed phrase friction. Multi-chain support Ethereum, Polygon, BNB Chain, Solana, Bitcoin. Transaction signing and broadcasting. Portfolio balance displays. Hardware wallet integration.

Wallet Architecture Comparison Custodial vs Non-Custodial vs MPC vs Embedded

  • Custodial: Key Management Platform controls private keys. User trusts the platform. User Experience Simplest UX just a username/password. No seed phrases. Best For Exchanges, neobanks, corporate treasury management where regulation requires custody controls.
  • Non-Custodial (EOA): Key Management User controls private key / seed phrase. Platform has no access. User Experience User manages seed phrase. Self-custody, full ownership, full responsibility. Best For DApps, DeFi protocols where user self-custody is a core product value.
  • Non-Custodial (MPC): Key Management Private key split between user and platform neither holds the complete key. User Experience No seed phrase needed. Users can recover access. Platform cannot unilaterally move funds. Best For Institutional wallets, fintech apps, enterprise blockchain use cases requiring recovery options.
  • Embedded / Smart Wallet: Key Management EIP-4337 smart contract wallet key management via social login or MPC. User Experience Social login (email/Google). No seed phrase. Sponsored gas. Batch transactions. Best For Consumer apps, gaming, NFT platforms where crypto-native UX is a barrier to adoption.

MPC for Wallet Key Management

MPC (Multi-Party Computation) is a cryptographic technique that allows multiple parties to jointly compute a function (in this case, a digital signature) without any party revealing their input (their key share) to the others. In wallet key management: the user's private key is mathematically split into multiple shares, distributed between the user's device, the platform's server, and optionally a third backup. To sign a transaction, a threshold number of shares (typically 2-of-3) must participate in a distributed signing ceremony the complete private key is never reconstructed in any single location. Advantages over HSM-only custody: no single point of compromise (an attacker who compromises the server does not have the complete key), user recovery (if the user loses their device, the remaining shares can be used to generate a new key share), and better UX than seed phrases (no 24-word phrase to manage). Privy, Dynamic.xyz, and Fireblocks all use MPC for non-custodial or semi-custodial wallet key management.

What this engagement delivers

Custodial Wallet Backend

Custodial wallet infrastructure for exchanges and financial platforms: HSM key management (Hardware Security Module private keys never exposed in plaintext, signing happens inside the HSM AWS CloudHSM or Thales Luna HSM for institutional-grade key security), MPC (Multi-Party Computation private key split between multiple parties using threshold signature schemes, no single party holds the complete key, k-of-n threshold required for signing), transaction approval workflows (multi-signature approval for large transactions, time delays for unusual patterns, fraud detection integration), regulatory compliance (KYC/AML integration, travel rule compliance for transfers above thresholds, transaction monitoring, SAR filing process).

Non-Custodial Embedded Wallet

Embedded wallet infrastructure using managed SDK solutions: Privy (embedded wallet SDK email, social, or SMS login generates a non-custodial wallet, MPC-based key storage, no seed phrase for the user, supports EVM chains and Solana), Alchemy Account Kit (EIP-4337 smart contract wallets social login creates a smart wallet, gas sponsorship via Alchemy's paymaster, session keys, batch transactions), Dynamic.xyz (multi-chain embedded wallets with authentication combines traditional auth with Web3 wallet creation), integration pattern (embedded wallets created transparently when the user signs up users who are not crypto-native never see blockchain complexity).

Multi-Chain Wallet Support

Wallet functionality across multiple blockchain networks: EVM chains (Ethereum, Polygon, BNB Chain, Avalanche, Base, Arbitrum, Optimism single key pair works across all EVM chains), Solana (separate key pair, different address format, @solana/web3.js for Solana interactions), Bitcoin (UTXO model, different address formats P2PKH, P2SH, P2WPKH bitcoinjs-lib or bitcoin-core RPC), chain detection (display correct network, warn on wrong network, support chain switching), cross-chain portfolio (aggregate balances across all supported chains in unified portfolio view).

Transaction Management

Production transaction infrastructure: nonce management (track the nonce for each wallet address, increment correctly for sequential transactions, recover from nonce gaps after failed transactions), gas price estimation (use EIP-1559 base fee + priority fee estimation `eth_feeHistory` API for accurate gas pricing, configurable max fee and max priority fee), transaction broadcasting (submit transaction to the network via Alchemy or Infura, return transaction hash immediately, track confirmation status via WebSocket subscription or polling), transaction history (index historical transactions via Alchemy Transfers API or Etherscan API display full transaction history with token transfers, gas paid, and status).

Hardware Wallet Integration

Hardware wallet support for high-security users: Ledger (Ledger Live SDK detect device, connect via USB or Bluetooth, prompt for account selection, sign transaction with device), Trezor (Connect SDK web-based and mobile integration, transaction signing flow, device detection), integration pattern (application detects if user has a hardware wallet, offers option to connect instead of software wallet, routes signing requests through device).

Process

  1. Phase 1 · Week 1-2

    Wallet Architecture Design

    Custody model decision (custodial vs non-custodial vs MPC), key management approach (HSM vs MPC vs software), compliance requirements (KYC/AML, Travel Rule), technical specification. Deliverable: Wallet Architecture + Compliance Plan.

  2. Phase 2 · Week 2-4

    Embedded Wallet Integration

    Privy/Alchemy Account Kit SDK integration, social login setup, wallet creation on user sign-up, multi-chain support (EVM + Solana), portfolio display. Deliverable: Embedded Wallet + Portfolio UI.

  3. Phase 3 · Week 3-6

    Custodial Backend Development

    HSM (AWS CloudHSM) configuration, MPC threshold signature setup, transaction approval workflows (multi-sig), KYC/AML integration (Onfido/Chainalysis), transaction monitoring. Deliverable: Custodial Wallet Backend + Compliance.

  4. Phase 4 · Week 3-5

    Transaction Management

    Nonce management (tracking, gap recovery), gas price estimation (EIP-1559), transaction broadcasting, WebSocket confirmation tracking, transaction history indexing (Alchemy Transfers API). Deliverable: Transaction Pipeline + History.

  5. Phase 5 · Week 4-5

    Hardware Wallet Integration

    Ledger/Trezor Connect SDK integration, device detection, account selection, transaction signing flow, fallback to software wallet. Deliverable: Hardware Wallet Support.

Tech stack

Custodial Key Management
AWS CloudHSM, Thales Luna HSM, Fireblocks MPC, Coinbase Custody, BitGo
Embedded Wallets
Privy (email/social login, MPC), Alchemy Account Kit (EIP-4337, gas sponsorship), Dynamic.xyz (multi-chain, traditional auth)
EVM Chains
Ethereum, Polygon, BNB Chain, Avalanche, Base, Arbitrum, Optimism single key pair across all EVM chains
Non-EVM Chains
Solana (@solana/web3.js), Bitcoin (bitcoinjs-lib, bitcoin-core RPC)
Transaction Infrastructure
Alchemy (NFT API, Token API, Transfers API), Infura, QuickNode, Etherscan API
Hardware Wallets
Ledger Live SDK, Trezor Connect, WalletConnect (hardware wallet support)
Compliance
Chainalysis (transaction monitoring), Elliptic, Onfido (KYC), Jumio

How we work

4-Architecture Comparison

Custodial vs Non-Custodial (EOA) vs MPC vs Embedded/Smart Wallet with key management, UX, best for | Basic: Single wallet type

Privy + Alchemy Account Kit + Dynamic.xyz

Embedded wallet SDKs social login, no seed phrase, gas sponsorship, session keys | Basic: EOA only (seed phrase barrier)

AWS CloudHSM Named

Hardware Security Module private keys never exposed in plaintext, signing inside HSM | Basic: Software-only key storage

EIP-4337 Session Keys

Smart contract wallets session keys for games/high-frequency interactions without signing each time | Basic: Sign every transaction

FATF Travel Rule Named

Compliance requirement for custodial wallets transaction monitoring, SAR filing | Basic: No compliance integration

Where this is used

Exchange Custodial Wallet

Centralised exchange backend: HSM key management (AWS CloudHSM), multi-sig approval for large withdrawals, KYC/AML integration (Onfido), Travel Rule compliance (Chainalysis). Processes 10K+ user withdrawals daily.

Consumer App Embedded Wallet

Privy embedded wallet: social login (email/Google), wallet created on sign-up (invisible to user), multi-chain (Ethereum + Polygon), gas sponsorship via Alchemy paymaster. 50K wallets created in first month, 0 seed phrase support tickets.

DeFi Portfolio Tracker

Multi-chain portfolio display: EVM chains (Ethereum, Polygon, Arbitrum) + Solana. Real-time balance updates via WebSocket, transaction history via Alchemy Transfers API. USD conversion via price feeds.

Institutional MPC Wallet

MPC key management for corporate treasury. Private key split 2-of-3 between CEO, CFO, and external custodian. Approval workflows for large transactions. 30-day time lock for critical operations.

Pricing guidance

These ranges are planning anchors. The quote names scope, timeline, and what is excluded. Talk through a quote.

Wallet Architecture Design

$4,000 - $8,000

1 - 2 weeks

Custody model, key management approach, compliance requirements, technical spec

Embedded Wallet (Privy/Alchemy)

$8,000 - $22,000

3 - 6 weeks

SDK integration, social login, multi-chain, portfolio display, transaction history

Custodial Wallet Backend

$15,000 - $45,000

5 - 10 weeks

HSM/MPC key management, approval workflows, transaction monitoring

Multi-Chain Portfolio Display

$5,000 - $14,000

2 - 4 weeks

Balance aggregation, transaction history, token prices, chain switching

Transaction Management

$5,000 - $12,000

2 - 4 weeks

Nonce management, EIP-1559 gas, broadcasting, status tracking

Hardware Wallet Integration

$4,000 - $10,000

2 - 3 weeks

Ledger + Trezor connect, transaction signing flow, device detection

Full Wallet Platform

$25,000 - $80,000

6 - 12 weeks

Custodial + embedded + multi-chain + compliance + mobile app

FAQs

What is the difference between custodial and non-custodial wallets?

In a custodial wallet, the platform stores and manages the user's private keys the user trusts the platform to secure their assets and execute transactions on their behalf. This is the model used by centralised exchanges (Coinbase, Binance) simple UX, platform is responsible for security, but the user does not "own" the keys in the cryptographic sense (the platform could freeze the account). In a non-custodial wallet, the user controls their own private keys the platform has no access to the keys and cannot move funds without the user's signature. This is the model used by MetaMask, hardware wallets, and self-custody wallets. MPC (Multi-Party Computation) wallets offer a middle ground: the private key is split between the user and the platform using a threshold signature scheme neither party holds the complete key, both must participate in signing, and the user can recover access if they lose their device. The choice depends on your regulatory environment and user base: custodial is simpler for regulated financial products, non-custodial is preferred for DeFi and Web3-native users.

What is MPC (Multi-Party Computation) for wallet key management?

MPC (Multi-Party Computation) is a cryptographic technique that allows multiple parties to jointly compute a function (in this case, a digital signature) without any party revealing their input (their key share) to the others. In wallet key management: the user's private key is mathematically split into multiple shares, distributed between the user's device, the platform's server, and optionally a third backup. To sign a transaction, a threshold number of shares (typically 2-of-3) must participate in a distributed signing ceremony the complete private key is never reconstructed in any single location. Advantages over HSM-only custody: no single point of compromise (an attacker who compromises the server does not have the complete key), user recovery (if the user loses their device, the remaining shares can be used to generate a new key share), and better UX than seed phrases (no 24-word phrase to manage). Privy, Dynamic.xyz, and Fireblocks all use MPC for non-custodial or semi-custodial wallet key management.

What is EIP-1559 and how does it affect transaction gas management?

EIP-1559 (implemented in Ethereum's London upgrade, August 2021) changed the gas fee mechanism from a simple auction to a base fee + priority fee model. Before EIP-1559: users bid for block space with a gas price unpredictable, often resulted in overpaying. After EIP-1559: every block has a base fee (algorithmically determined by network congestion, burned not paid to validators), plus an optional priority fee (tip to validators for faster inclusion), and a max fee per gas (the maximum the user is willing to pay prevents overpaying if the base fee spikes between transaction submission and inclusion). For wallet developers: use `eth_feeHistory` to estimate an appropriate max fee and priority fee based on recent blocks, set maxFeePerGas and maxPriorityFeePerGas in the transaction rather than gasPrice (legacy format), and display the estimated transaction cost to the user before signing.

What compliance requirements apply to crypto wallet applications?

Compliance requirements for crypto wallet applications depend on the jurisdiction and business model. For custodial wallets (where the platform holds keys on behalf of users): KYC/AML (Know Your Customer / Anti-Money Laundering) requirements apply in most jurisdictions user identity verification before allowing transactions above thresholds, transaction monitoring for suspicious patterns, SAR (Suspicious Activity Report) filing obligations. Travel Rule (FATF Recommendation 16): for transactions above $1,000/$3,000 (jurisdiction-dependent) between custodial service providers, the originating VASP must transmit identifying information about the sender and recipient to the receiving VASP. For non-custodial wallets where the platform does not hold keys: less stringent requirements in most jurisdictions, but the regulatory environment is evolving rapidly. ClickMasters integrates compliance tooling (Chainalysis, Elliptic for transaction monitoring; Onfido, Jumio for KYC) but recommends the client obtain specific legal advice for their jurisdiction before launch.

Related reading

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