💻 Full Stack Developer for Crypto Payments Service

POS + Web Snippet (Square & Verifone-Compatible)

Company: TrimVault.app (Crypto Payments Startup, USA)

Summary: We’re launching TrimVault.app — a Toast-like payment platform that helps bars, restaurants, and gas stations cut payment fees from 2–3% down to ~1.5%, powered by Circle. No crypto wallets, no hardware changes — just faster, smarter payments.

💰 Fixed Price
$2,000 USD

⚙️ Experience
Intermediate / 5+ Years

🌍 Location
Remote (Worldwide)

🚀 Ongoing Project | Auto-Updating Crypto Payments Platform

🧠 Project Overview

The platform combines POS + Web Embed + Dashboard in one unified codebase. It supports both Square (for bars/restaurants) and Verifone (for gas stations), powered by the Circle API with auto pre-authorization and capture. Everything updates automatically through Vercel — no client-side maintenance.

💻 Tech Stack

• Node.js, React, React Native
• Circle API (pre-auth/capture, USDC conversion)
• Ramp API (backup provider)
• Wise API (ACH payouts)
• Venmo API (staff splits)
• Verifone SDK + Square Web Bluetooth
• Vercel hosting + cron jobs

⚙️ Deliverables

• Web Embed Snippet: One HTML/JS block (~80 lines) usable on Wix, Squarespace, or Verifone web views.
• POS App: Single React Native app (Android & iOS) supporting both Square and Verifone terminals.
• Cron Script: Nightly payouts using Node.js, Circle, and Wise APIs.
• Owner Dashboard: Simple live stats page hosted on Vercel with auto updates.
• Auto-Update System: All client-facing components pull live code from Vercel — no manual updates.
• Demo Video (3 min): Show embed, POS use, refunds, tip/tax/split flow, and auto-update proof.

📲 Payment Flows

🍹 Bar / Restaurant Mode

• Toast-style UI with green theme and big round Pay button.
• Auto tax + tip sliders (10% / 15% / 20%).
• Optional subscription toggle (monthly billing via Circle vault).
• Split tips between staff via Venmo.
• Refunds trigger Circle reversal + email receipt.

⛽ Gas Station Mode

• No UI — tap-to-pay handled via Verifone passthrough.
• Circle pre-authorization ($50 hold) → final capture (e.g., $45.23).
• Silent operation with complete webhook logs.
• Refund via dashboard with email receipt.

💵 Payout Logic

Each night, the cron.js script totals all payments, fetches Circle’s live fee rate, adds a 0.5% Trim buffer, subtracts total fees, and pays out to clients via Wise ACH (flat $0.35 fee). All payouts and logs are stored as JSON and CSV — no database needed.

🎯 Requirements

• Strong skills in Node.js, React, React Native.
• Hands-on experience with Circle or Ramp APIs (pre-auth / capture flows).
• Familiar with Verifone SDK passthrough and Square integrations.
• Experience deploying auto-updating scripts and apps via Vercel.
• Solid understanding of secure, scalable payment systems.

🧩 Ideal Candidate

• 5+ years full-stack development experience.
• Portfolio showing crypto payment or POS projects.
• Strong debugging and testing skills.
• Available to deliver by end of October.

📬 How to Apply

Submit your proposal with:

• Examples of crypto or payment integrations you’ve built.
• Your plan for building a unified config.mode = 'bar' | 'gas' system.
• Timeline to deliver the full package.
• Sandbox demo links (if available).

Apply on Upwork

⚠️ Tip: Apply only through official Upwork links. Do not share private keys or wallet data.