Akira Watanabe Senior Web3 Developer
Tokyo, Japan • dappdev@gmail.com • +81 3-5555-0148
Profile Summary
- Senior Web3 Developer with 7 years of experience shipping production dApp frontends and wallet flows on Ethereum and Polygon across DeFi swap and lending UIs, NFT marketplaces, and consumer wallet apps, specializing in wallet UX, transaction state machines, and Sign-In with Ethereum auth flows.
- Hands-on coverage across frontend framework (React with Next.js), Web3 client (viem with wagmi), wallet kit (RainbowKit with WalletConnect), and chain (Ethereum mainnet with Polygon), with indexing through The Graph with Alchemy fallback and credentialed as Alchemy University Web3 Developer.
- Deep expertise in dApp frontend architecture with App Router, server components, and edge rendering, transaction state machines covering pending, confirmed, reverted, and dropped paths, wallet connection layer spanning EIP-1193 providers, SIWE auth, and chain switching, and indexer integration with The Graph subgraphs, Alchemy webhooks, and IPFS metadata resolvers, applying methodologies such as optimistic UI for tx flows with rollback on revert and resilient retry on RPC drops and gas estimation surfaces with EIP-1559 fee preview and slippage controls per swap to deliver approachable dApps that onboard non-crypto-native users without dropping a transaction.
- Engaged collaborator working cross-functionally with product, design, smart contract, and protocol research teams in consumer Web3 engineering teams shipping public dApps weekly, contributing to RFCs on wallet UX, incident response on RPC outages, and design reviews for tx confirmation flows with an ownership-first mindset and clean handoffs.
- Mentor who shares technical excellence and fosters a culture of resilient wallet flows that survive network congestion and accessible Web3 UX that meets first-time-wallet users where they are through PR reviews and pattern libraries, while running the internal dApp UX guild and the Web3 frontend hiring loop and authoring widely cited wagmi extensions and dApp UX patterns.
Technical Skills
- Languages:
- TypeScript, JavaScript, Solidity 0.8.x (reading), Rust with Anchor (reading), Node.js, GraphQL, HTML, CSS
- Frameworks & Frontend:
- React with Next.js, Remix, SvelteKit, Vue with Nuxt, Tailwind CSS, Radix UI, Framer Motion, React Query, Zustand
- Web3 Libraries & Clients:
- viem with wagmi, ethers.js v6, web3.js, @solana/web3.js, Anchor client, Cosmos SDK CosmJS, EIP-1193 providers, EIP-6963 multi-wallet
- Wallets & Auth:
- RainbowKit with WalletConnect, MetaMask, Coinbase Wallet, Rainbow, Phantom, Web3Modal v3, ConnectKit, Sign-In with Ethereum (SIWE), session keys
- Chains & Networks:
- Ethereum mainnet with Polygon, Arbitrum One, Optimism, Base, zkSync Era, Polygon zkEVM, Solana, Cosmos zones, EVM testnets (Sepolia, Holesky)
- Data & Indexing:
- The Graph with Alchemy fallback, The Graph subgraphs, Alchemy, Infura, QuickNode, Moralis, Covalent, Goldsky, Tenderly Web3 Actions, GraphQL codegen
- Decentralized Storage & Infra:
- IPFS with Pinata, Arweave, Filecoin, NFT.Storage, web3.storage, ENS, Lit Protocol, Push Protocol, Vercel and Cloudflare edge hosting
- Certifications & Communities:
- Alchemy University Web3 Developer, Alchemy University, Buildspace, LearnWeb3, ETHGlobal hackathon participant, ConsenSys Academy, Devpost project contributor
Education
Tokyo Institute of
Technology
B.Sc. in Computer
Science
Work Experience
Wallet Labs
Senior Web3
Developer
- Owned dApp development end to end on the consumer wallet dApp and swap surface serving 1.8M monthly active wallets, driving wallet UX, tx state design, and indexer wiring across 9 chains with the frontend, the contract glue, and the indexer pipeline all stitched together by one team.
- Wired wallet integration and Sign-In with Ethereum auth through RainbowKit, WalletConnect v2, Coinbase Wallet SDK, Phantom adapter, and SIWE session auth, EIP-6963 multi-wallet discovery, chain-switching prompts on mismatched networks, and account change listeners that survive page reloads, supporting 34 wallet variants with a connect success rate of 96% across mobile and desktop entries.
- Built smart contract integration on viem read and write paths against router, vault, and ERC-20 contracts with typed ABIs and simulated calls, eth_call simulation before signing, gas estimation with EIP-1559 surfacing, and event-log polling with reorg handling, wiring 140 contract methods into the dApp with a tx success rate of 99.2% across mainnet and L2 traffic.
- Standardized the Web3 library layer around wagmi hooks for connection state, viem for typed calls, ethers.js v6 on legacy paths, and React Query for cache and retries, a typed contract registry with codegen from ABIs, and a shared error mapper for revert reasons, cutting the wallet bundle from 420KB to 180KB and shipping 42 reusable hooks adopted across product teams.
- Designed Web3 UX and transaction flows around optimistic tx state machines, EIP-1559 gas previews with slippage controls, network-switch prompts, and clear failed-tx recovery copy, pending-to-confirmed status tracking with block-explorer deep links, retry-with-bump on dropped transactions, and gentle warnings on flagged contracts, dropping the failed-tx rate from 11% to 2.4% and onboarding 640k first-time wallet users to the swap flow.
- Built blockchain data and indexing through The Graph subgraphs, Alchemy webhooks for live events, Moralis for cross-chain history, and Goldsky mirrors for analytics, cursor-paginated queries on activity feeds, decoded log streams pushed into Redis, and reorg-aware cache invalidation on confirmed blocks, maintaining 22 subgraphs that index 3.4M daily events with no missed event window in the last two quarters.
- Drove frontend performance and accessibility through Next.js App Router with server components, route-level code-splitting, lazy-loaded wallet modals, and Axe-driven a11y audits across the swap flow, image optimization on NFT thumbnails, prefetch on hover for the route into the swap, and skeleton states for pending RPC reads, cutting LCP from 3.8s to 1.6s and lifting the Axe a11y score to 98 across the wallet dApp.
Mercari (NFT
Lab)
Frontend Engineer,
Web3 Squad
- Surfaced decentralized storage and NFT assets through IPFS pinning with Pinata, Arweave for permanence, NFT.Storage for metadata, and ENS for marketplace handles, gateway fallback when Pinata throttled, CID-based image preview with progressive loading, and metadata schema validation before listing, displaying 280k NFTs on the marketplace surface with pin uptime of 99.9% over the year.
- Held the contract-aware seat on the squad with reading Solidity ABIs end to end, prototyping helper contracts in Foundry, and pairing with Smart Contract Developers on Hardhat reviews, typed bindings generated from ABIs, revert-reason decoding in error toasts, and gas-cost annotations on docs, shipping 58 typed ABIs into the codebase and supporting 34 contract reviews from the frontend seat.
- Integrated the ecosystem and protocol layer around ERC-20, ERC-721, and ERC-1155 token standards, Chainlink price feeds, OpenSea Seaport orders, and Snapshot DAO voting widgets, cross-chain bridge UIs over LayerZero messages, and a thin Cosmos SDK adapter for an early cross-chain experiment, integrating 14 protocols across 5 chains without a signature replay or order-mismatch incident.
- Stood up the dApp frontend foundation on React with Next.js Pages Router, ethers.js v5 for tx flows, Web3Modal for wallet entry, and Tailwind for the marketplace UI, a custom wallet-state context with localStorage persistence, and a tx-status drawer wired to event logs, shipping 46 Web3 features into a marketplace that reached 180k active dApp users.