Mi Tanda is an on-chain ROSCA (a tanda / cundina — rotating savings club). Members each contribute a fixed amount per cycle, and one member receives the full pot each cycle, rotating until everyone has received exactly once. Because it's smart-contract enforced, no organizer can run off with the money — the rules, the pot, and the payout order all live on-chain.
Built for Latino/Hispanic communities and non-crypto users: the chain is hidden behind email/social login, and contributions are made in a stablecoin people already understand (the Mexican-peso stablecoin MXNB, or USDC).
🌐 Live: mitanda.online
Smart contracts live in a separate repo: GeObts/mitanda-contracts. This repo is the frontend that drives them; the two together are the full project.
📄 Product Requirements Document: docs/PRD.md ·
🧭 Project context / current state: MITANDA_PROJECT_CONTEXT.md
flowchart TD
User([User])
User --> Web["mitanda.online<br/>Web app · Privy login"]
User --> BaseApp["base.mitanda.online (beta)<br/>Base App · Base Account"]
Web --> SDK["wagmi + viem"]
BaseApp --> SDK
SDK --> Manager["TandaManager<br/>Arbitrum One + Base mainnet"]
Manager --> Clones["Tanda clones<br/>one ROSCA each"]
Manager --> NFTs["Pass / Receipt / Completion NFTs"]
Manager --> VRF["Chainlink VRF v2.5<br/>random payout order"]
Manager --> Insurance["Insurance Pool<br/>Etherfuse CETES yield"]
| Sponsor | How Mi Tanda uses it |
|---|---|
| Arbitrum One | The main chain — all production tandas run here. v4 audit-hardened contracts, live mainnet. |
| Bitso / MXNB | MXNB, the Mexican-peso stablecoin, is the headline contribution currency on Arbitrum — members save in pesos, not an unfamiliar asset. |
| Base | The Base App distribution build; contracts are deployed and verified on Base mainnet, with the Base App build in progress. |
| Etherfuse / CETES | Insurance-pool yield — idle defaulter-insurance reserves earn Mexican government-bond (CETES) yield via Etherfuse. See docs/ETHERFUSE.md (written by the Etherfuse integration; link goes live when published). |
- Web app: mitanda.online — Arbitrum One, Privy login.
- Base App: base.mitanda.online — Base mainnet, Base Account auth · Beta (mobile experience in active development).
Both mainnets run the same v4 audit-hardened contracts (commit d17e039).
Tanda clones are minimal proxies of one implementation; the Manager orchestrates
Chainlink VRF v2.5 for the randomized payout order.
| Contract | Address |
|---|---|
| TandaManager | 0xa88aB3B81D9cA6BB556104B72e73b722D3abE678 |
| Tanda implementation | 0xD55c72B7fF4777D382Bd69b9B27Cc1da799d119d |
| MitandaPassNFT | 0x52ff9dBb6124E3EBCEbA75A875A43d1752c0F277 |
| MitandaReceiptNFT | 0x00e904e04156d13Eb35D8404053e2eDE02aDAB96 |
| MitandaCompletionNFT | 0x1CB29BCb3Dc1bF7B4A7083F779c488BF4a55573d |
Tokens: MXNB 0xF197…80aA ·
USDC 0xaf88…5831
| Contract | Address |
|---|---|
| TandaManager | 0x74b6Fc121A40C1A3282af6Bd78074AC3C2a32814 |
| Tanda implementation | 0x7Ee43871c368901652F9b15A2ed28603Bc7A0bB9 |
| MitandaPassNFT | 0xe9A5c185F5ab2A9434a880C92DB8A51014C75e5f |
| MitandaReceiptNFT | 0x0dDb8bC0bD88d7933Dc4B54618768156a3558443 |
| MitandaCompletionNFT | 0xCF006fe8E86E7Fd92A7fD2f9E0A64dc4761AfAB3 |
Token: USDC 0x8335…2913
(MXNB isn't native to Base; Base tandas use USDC.)
- Frontend: Next.js 16 (App Router) · React 19 · Tailwind CSS v4 · shadcn/ui
- Web3: Privy (web auth) · wagmi v3 · viem · TanStack Query · Base Account (Base App)
- Contracts: Solidity 0.8.20 · Foundry · OpenZeppelin · Chainlink VRF v2.5
- Hosting: OpenNext on Cloudflare Workers
A complete tanda runs end-to-end from the dashboard — no block-explorer calls needed:
- Create — start a savings circle (amount per cycle, member count, interval, public or private). The creator is auto-enrolled at create time (cycle 1 paid), so they never need a separate "join" step.
- Join — others join a public tanda by ID, or a private one via an EIP-712 signed invite (per-address ticket) or an approved join request.
- Pay — members pay one or more cycles ahead; pull-payment throughout.
- Cycle payout — once the circle fills, Chainlink VRF randomizes the payout order; each cycle the current recipient receives the pot (recipient 95% / organizer 3% / platform 2%).
- Completion — after everyone has received once, the tanda completes with a soulbound completion NFT and no trapped funds.
- Insurance refund — honest members get their defaulter-insurance deposit refunded; if someone defaults past grace, their insurance is slashed to cover the gap and unblock the payout.
Soulbound membership/completion NFTs and transferable payout receipts are minted
along the way. Every read is pinned to the active chain and derived from on-chain
state (getPayoutOrder, getAllParticipants, gracePeriod).
e2e-evidence/ holds screenshots from driving the real UI
against the live v4 contracts on a mainnet fork — the full lifecycle (create →
join → VRF → cycles → completion + insurance refunds), the release flow, and a
complete default + insurance payout, each cross-checked against on-chain state.
The deployed mainnet implementation bytecode is a byte-for-byte match to the code
that passed the 91-test suite and the full fork lifecycle.
npm install
cp .env.example .env.local # add NEXT_PUBLIC_PRIVY_APP_ID + RPC overrides (no secrets committed)
npm run dev # http://localhost:3000Regenerate ABIs from the contracts repo with node scripts/gen-abis.mjs.
The Base App build + deploy runbook is in docs/BASE_APP.md.
Goyabean — solo builder (product, smart contracts, and frontend), built with Claude Code.