Dpay

dPay — Delegated Family Payments

Tagline: Your family's wallet, your keys, your control.

🎯 Problem

Managing family finances on-chain is broken. Today, if you want to give your spouse or kids spending money, you have two bad options:

1. Transfer funds to their wallet — You lose custody. Once sent, you can't control how it's spent or get it back.

2. Share your private keys — Terrible security. Full access means full risk.

Traditional apps like GPay solve this with custodial accounts, but that means trusting a centralized entity with your money. They can freeze accounts, impose limits, and you're locked into their ecosystem.

What if you could give your family spending power without giving up custody?

💡 Solution

dPay is a non-custodial family budget management app powered by ERC-7715 delegation.

The family head (e.g., Dad) holds all funds in a single smart account. Family members receive spending permissions — not funds. They can spend up to their budget directly from the family vault, without Dad ever transferring tokens or sharing keys.

> Think of it like a corporate card: the company owns the money, employees can spend within limits, and access can be revoked instantly.

⚙️ How It Works

┌─────────────────┐ ERC-7715 ┌─────────────────┐

│ Family Head │ ──── Delegate Budget ───► │ Family Member │

│ (Vault) │ │ (Mom/Son/etc) │

└─────────────────┘ └─────────────────┘

│ │

│ Funds stay here │ Can spend up to limit

▼ ▼

┌─────────────────┐ ┌─────────────────┐

│ Smart Account │ ◄── redeemDelegations ─── │ Member's Wallet │

│ (Holds $$$) │ │ (No funds req) │

└─────────────────┘ └─────────────────┘

│

▼

┌─────────────────┐

│ Envio Indexer │ ──► Real-time Dashboard

└─────────────────┘

1. Family head creates a vault — A smart account that holds all family funds

2. Delegates budgets to members — Using MetaMask's delegation framework (ERC-7715)

- Mom: $500/month

- Son: $50/week

- Daughter: $50/week

3. Members spend directly — When they need to pay, they call redeemDelegations() which executes a transfer from the vault

4. Real-time tracking — Envio indexes all spends, showing who spent what, when, and where

5. Instant revoke — One click to revoke any member's access

✨ Key Features

| Feature | Description |

|---------|-------------|

| Non-Custodial | Family head keeps full custody — only delegates spending capability, not funds |

| Granular Budgets | Set per-member limits: weekly, monthly, or custom periods |

| Hard Limits | Enforced on-chain by SpendingLimitEnforcer — can't be overridden |

| Instant Revoke | Remove access in one transaction — no support tickets |

| Real-Time Dashboard | Track all family spending with Envio-powered analytics |

| No Pre-Funding | Members don't need tokens in their wallets to spend |

| Multi-Token Support | Works with any ERC-20 token |

🔧 Technical Architecture

Smart Contracts

- MetaMask DelegationManager — Core delegation framework

- SpendingLimitEnforcer — Enforces budget limits per period

- TimestampEnforcer — Handles permission expiry

Indexer (Envio)

- Indexes RedeemedDelegation events

- Decodes actual spend amounts from transaction calldata

- Tracks per-member spending against budgets

- Provides GraphQL API for dashboard

Backend (Supabase)

- Stores delegation metadata and permission contexts

- User authentication and family management

- Aggregates data from Envio for fast queries

Frontend

- Family dashboard with spending analytics

- Member view showing remaining budget

- One-click delegation and revocation

🆚 GPay vs dPay

| | GPay | dPay |

|---|---|---|

| Custody | Google holds your money | You hold your keys |

| Budget Control | Soft limits, can override | Hard on-chain limits |

| Revoke Access | Contact support, wait days | One click, instant |

| Censorship | Can be frozen | Permissionless |

🎯 Use Cases

1. Family Allowances — Give kids weekly spending money without transferring tokens

2. Household Budgets — Spouse can pay bills from shared vault

3. Elderly Care — Allow caretakers limited spending access for an elderly parent

4. Travel Budgets — Give family members travel spending limits that auto-expire

5. Shared Subscriptions — Delegate exact amounts for recurring payments

🛠 Tech Stack

- Blockchain: Base Sepolia, Sepolia

- Delegation: MetaMask Delegation Framework (ERC-7715)

- Indexing: Envio HyperIndex

- Backend: Supabase

- Frontend: Next.js, React, TailwindCSS

- Wallet: MetaMask, WalletConnect

🚀 What's Next

- [ ] Multi-sig family vaults (require 2 parents to approve large spends)

- [ ] Merchant whitelists (kids can only spend at approved stores)

- [ ] Spending notifications (real-time alerts when family members spend)

- [ ] Budget rollover (unused allowance carries to next period)

- [ ] Mobile app with push notifications