Web Developer (MERN) — Multi-Chain Chrome Extension Crypto Wallet

Web Developer (MERN) — Multi-Chain Chrome Extension Crypto Wallet

Location: Remote

Type: Contract, starting with an MVP, then ongoing product work

Compensation: $11,000 – $13,000

Experience: Mid-level to senior

About the project

We’re building a Google Chrome extension crypto wallet on the MERN stack (MongoDB, Express, React, Node.js). The product should let users create/import wallets, manage accounts, send and receive assets, and interact with dApps from the browser — with security as a first-class requirement.

Engagement

Phase 1 is a shippable MVP. After MVP, this continues as long-term product work: new chains, features, hardening, Chrome Web Store updates, and production support.

Supported networks (MVP + roadmap)

Must be designed as multi-chain from day one, with Ethereum, Solana, BNB, and XRP in the first wave, then the rest:

1. Ethereum

2. Solana

3. BNB Smart Chain

4. XRP Ledger

5. Bitcoin

6. Polygon

7. Avalanche

8. Arbitrum

9. Optimism

10. Base

11. Cardano

12. Tron

13. Litecoin

14. Cosmos

15. Toncoin (TON)

The role

You’ll own end-to-end development of the extension and its backend: UI, extension architecture (popup, background/service worker, content scripts), APIs, wallet flows, and production-ready security practices.

Responsibilities

• Design and build a Chrome Manifest V3 extension (popup, options, background service worker, content scripts)
• Build the wallet UI in React (onboarding, create/import wallet, dashboard, send/receive, transaction history, network/asset switcher, settings)
• Implement Node.js/Express APIs and MongoDB models for non-sensitive app data (user prefs, metadata, analytics — never store seed phrases or private keys on the server)
• Implement client-side key management: seed phrase / private key generation, encryption at rest, unlock flow, session timeout
• Support core wallet operations across chains: address derivation, balances, send/sign transactions, network switching
• Integrate chain RPCs and (if in scope) dApp connection / provider injection
• Handle Chrome permissions, messaging between extension contexts, and secure storage (chrome.storage + encrypted secrets)
• Ship the MVP, then iterate on the long-term product (more chains, tokens/NFTs, UX, security, store releases)
• Write tests, document the architecture, and prepare a Chrome Web Store–ready build

MVP success

• Installable Manifest V3 extension
• Create and import wallet
• Send/receive on Ethereum, Solana, BNB, and XRP
• Clear architecture so additional chains can be added without a rewrite
• Keys never leave the client unencrypted; backend never holds seed phrases

Post-MVP (long-term)

• Remaining listed chains and a maintainable multi-chain module
• Token lists, transaction history, dApp connect, hardening, and store updates

Must-have skills

• Strong MERN experience (React, Node.js, Express, MongoDB)
• Production experience with Chrome extensions (Manifest V3)
• Strong JavaScript/TypeScript
• Crypto wallet fundamentals: HD wallets, seed phrases, public/private keys, signing, fees
• Multi-chain experience, especially EVM (Ethereum, BNB, Polygon, L2s), Solana, and willingness to implement XRP, Bitcoin, and other L1s
• Web3 libraries (e.g. ethers.js / viem, Solana web3.js / Kit, chain-specific SDKs)
• Security mindset: XSS, phishing, message validation, least-privilege permissions
• Git/GitHub and clear written communication

Nice to have

• TypeScript in both extension and API
• WalletConnect, dApp provider injection, or hardware wallets
• Chrome Web Store publishing
• NFTs, fiat on-ramp, multi-account UX
• CI/CD, automated tests, code review habits

How to apply

Send

1. Resume / GitHub

2. Links to Chrome extensions or Web3/wallet work

3. A short note on how you’d structure a Manifest V3 multi-chain wallet (popup vs background vs content script, and how you’d add chains after MVP)

4. Which of the listed chains you’ve shipped before

5. Availability, MVP timeline, and confirmation of the $11,000–$13,000 range