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Mobile & Systems Engineer

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Mobile & Systems Engineer

Get In Touch
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Mobile & Systems Engineer

GigMint

Flutter · Dart · Polygon zkEVM · Web3.dart · ERC-4337 Paymaster · IPFS (Pinata) · Hive · Firebase Cloud Messaging · WalletConnect v2 · Bloc/GetX · Figma · Go · Polygon · Riverpod 

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Duration

12 Weeks

Location

Remote

Platform

IOS, Andriod

Screens

15+

Category

Web 3

Size

68.2

MB

GigMint - AppShot Screen 1 1
GigMint - AppShot Screen 1 2
GigMint - AppShot Screen 1 3
GigMint - AppShot Screen 1 4
GigMint - AppShot Screen 1 5

Project Description

Overview

Gigmint is a mobile-first decentralized freelance marketplace built with Flutter. It replaces traditional platforms like Upwork and Fiverr by eliminating their 20-30% fee structure with smart contract escrow on Polygon.

Freelancers keep 98.5% of earnings – paid instantly in USDC, not days. Clients post gigs, set milestones, and fund escrow. Smart contracts release payments per milestone approval. Disputes are resolved by a bonded arbitrator pool – no platform bias, no token required.

The platform combines a Flutter mobile app with on-chain smart contracts, delivering a Web3 experience that feels like a modern fintech app – fast, intuitive, and gas-abstracted.

Blockchain Agnostic: Designed for deployment on any EVM-compatible chain. Current implementation uses Polygon zkEVM for low gas fees and fast finality, with a modular contract layer enabling seamless migration to Ethereum L2s, Arbitrum, or Base as network needs evolve.

The Problem: Freelance platforms charge 20-30% in combined fees. Payments take 5-14 days to clear. Escrow is centralized – platforms can freeze funds arbitrarily. Dispute resolution is opaque and biased. Freelancers in emerging markets face additional banking restrictions. These inefficiencies cost the global gig economy over $50B annually in lost earnings and delayed payments.
The Solution: Gigmint replaces the middleman with smart contract escrow on Polygon:
  • 1.5% protocol fee – 90%+ savings for freelancers
  • Instant USDC settlements – <30 seconds, global, stable
  • Milestone-based releases – trustless, automated
  • Bonded arbitrator pool – fair, token-free dispute resolution
  • Gas abstraction (ERC-4337) – users pay gas in USDC; first 5 transactions subsidized
  • Sybil resistance – Gitcoin Passport + wallet history + stake option
  • Auto-release with challenge window – prevents fraud while protecting honest freelancers

Role

Lead Mobile Engineer

Highlight

Contribution

Full Flutter App Architecture

Built the entire mobile app from scratch with feature-first modules, repository pattern, and dependency injection. Achieved 60 FPS on mid-range devices.

Smart Contract Integration

Built a typed contract service layer for 5 on-chain contracts (Escrow, Arbitration, Reputation, Pause, Paymaster). Handled transaction polling, error recovery, and gas estimation.

Gas Abstraction (ERC-4337)

Implemented a paymaster client allowing users to pay gas in USDC. First 5 transactions subsidized – zero friction for new users.

IPFS Storage Integration

Built file upload/download service using Pinata SDK with background uploads, retry logic, and snapshot verification for external links

Mobile UI & Performance

Designed and built 15+ responsive screens with custom animations, bottom sheets, and snackbar toasts. Optimized build times by 30% with lazy loading and const constructors.

Offline & Push Notifications

Integrated web3dart and WalletConnect v2 for seamless wallet connection (MetaMask, Coinbase Wallet). Implemented secure local storage for session persistence.

Wallet Integration

Implemented local caching of contract states using Hive. Integrated Firebase Cloud Messaging for dispute alerts and milestone reminders with deep linking.

Mobile Security

Added certificate pinning, biometric authentication for sensitive actions, and runtime permission handling.

Process

Challenges, Outcome & Impact

Challenge

What I did

Impact

01

Preventing Fraud with Auto-Release

Added 3-day challenge window after review period. Client can dispute during this window. Manual arbitrator review available.
2% challenge rate – fraud prevented without harming honest freelancers.

02

Making Web3 Invisible to Mobile Users

Implemented ERC-4337 gas abstraction – users pay gas in USDC. First 5 transactions subsidized. Inline gas explanations with estimated costs in USD.
0% drop-off at transaction signing stage.

03

Building Trust Without a Token

Bonded arbitrator pool with 100 USDC stake. Protocol seeded first 50 arbitrators. 5% reward (min 10 USDC). Slashing for misconduct.
Saved $100k+ in token launch costs. Disputes resolved in <48 hours.

04

Scaling Reputation on Mobile

Floor reputation at 0. Recovery path: 3 dispute-free gigs restores score. One-time appeal to multisig for false disputes.
94% freelancer retention – new users recover from bad disputes.

05

Bridging Mobile, Design & Backend Teams

Detailed Figma annotations with interaction states, error handling, and API contract expectations. Conducted design QA sprints across Android and iOS.

40% faster frontend implementation – pixel-perfect delivery.

Product Quality: 15+ screens designed and built, 50+ component design system, <30 second USDC payments, 60 FPS on 95% of devices, 0% drop-off at transaction signing, 94% freelancer retention, 99.9% uptime guaranteed.