FlashBank

FlashBank

Non-custodial, on-chain lending where your funds stay in your wallet until the moment they're used. FlashBank is two complementary products that share that principle:

Branding rule: "flashbank" is only ever used as a verb (you flashbank a loan). FlashBank is not a bank, does not hold deposits and takes no custody as a financial institution.

Website: flashbank.net · Source: github.com/Rotwang9000/flashbank-net

Flash Loans (the Router)

FlashBankRouter is a multi-provider flash-loan pool where liquidity providers keep custody:

• No deposits. Providers approve the router and call setCommitment(token, limit, expiry, paused). WETH stays in their wallet and is only pulled for the microseconds of a flash loan.
• Atomic or nothing. The borrower implements IL2FlashLoan and must repay principal + fee in the same transaction, or the whole thing reverts.
• Configurable, bounded fees. Per-token feeBps (1–100 bps) with a separate owner cut (ownerFeeBps) and a per-tx max-borrow share of the pool (maxBorrowBps).
• Dual-control admin. Sensitive changes (token config, ownership, profit withdrawal) use a propose-then-execute flow split between the owner and a separate admin. See docs/security/DUAL_CONTROL.md.

Provider flow (WETH):

await weth.deposit({ value: ethers.parseEther("5") });        // wrap ETH (stays in your wallet)
await weth.approve(routerAddress, ethers.MaxUint256);         // approve once
await router.setCommitment(wethAddress, ethers.parseEther("3"), 0, false); // lend up to 3 WETH
// pause/resume any time — just flip the paused flag or drop the limit to 0

Borrower flow (MEV / arbitrage bots):

await router.flashLoan(
  wethAddress,
  ethers.parseEther("100"),
  true,            // receive native ETH (router unwraps WETH for you)
  strategyCalldata // forwarded to IL2FlashLoan.executeFlashLoan
);

Lives in flashloans/. Deploy with cd flashloans && npx hardhat run scripts/deploy-router.js --network <network> (set ADMIN_ADDRESS / TESTNET_ADMIN_ADDRESS in the repository-root .env). Per-network addresses are read from NEXT_PUBLIC_* env vars by the website.

P2P Term Loans

FlashBankP2PLoan is a neutral escrow that lets two parties flashbank a fixed-term, collateral-backed loan:

• Time-only settlement. Repay principal + a flat fee before maturity + grace, or the lender claims the collateral. Nothing is priced on-chain, so no oracle is needed.
• Optional surplus return (no oracle). An offer can set an agreed rate (stored as settlementValue — how much principal the whole collateral is taken to be worth, frozen at origination); on default the borrower then recovers any collateral beyond principal + fee. Leave it 0 for a pure pledge/forfeit. This honours Lorrow's surplus-return guardrail without an oracle — see docs/design/LORROW_COMPATIBILITY.md.
• Editable offers, front-running-safe. While an offer is open the creator can re-price or amend its non-escrow terms in place (updateOffer) and top up featured placement (boostOffer) without forfeiting the existing boost. Each edit bumps a version; a taker can call takeChecked(id, version) to pin the exact terms they reviewed.
• Flat fee, not interest. A single fixed fee rather than time-accruing interest — more compatible with faith-based finance that avoids riba (this is not a Sharia-certification claim).
• Three optional, default-off fees:
  • an opt-in interface fee (lender-paid, only on offers posted through flashbank; 0% introductory),
  • an optional boost that buys featured marketplace placement ranked by spend (an advert, not interest — non-refundable),
  • a per-offer service fee to any address (insurance / third party). Go direct on the contract and it is zero commission.
• Tokens are just ERC-20s. On mainnet/L2 the escrow uses real assets (WETH, USDC, …). On the testnet playground, fpETH/fpUSD are free faucet tokens with no value.

Lives in loans/. Full design: docs/design/P2P_LENDING_DESIGN.md.

Live on mainnet (Ethereum + Base)

FlashBankP2PLoan is deployed and verified on mainnet — judged solid by the self-audit and shipped while ETH gas was cheap. Same bytecode on each chain; Ownable, fee recipient = Vultisig vault, 0 bps introductory (a listing fee only ever applies to offers that opt in via listed, hard-capped on-chain at 1%). No external audit — use real assets at your own risk.

The mainnet UI uses real WETH/USDC. (Arbitrum pending — deployer balance too thin to deploy yet; add later with MAX_FEE_GWEI pinned low.) Per-chain records in loans/deployments/*-p2p.json.

Mainnet interface is restricted to ETH and USDC for now — custom-token entry is testnet-only — so the front end never invites an unknown/fake token (the contract itself stays permissionless for anyone calling it directly).

v2 — live on the Sepolia playground. FlashBankP2PLoanV2 adds on-chain token sanity-validation, a graduated cooling-off rebate (the flat fee vests from a 10% floor so a near-instant return is cheap — killing fake-token fee-farming — while consuming a listing is never free, and a same-block guard stops free flash loans), and pull-payout fallbacks so a blocklisted recipient can never brick the other party's repayment or default claim. Adversarially reviewed, unit-tested (22 cases) and deployed to Sepolia (verified, seeded) where it has passed a live two-agent lifecycle drill; mainnets stay on v1 until it graduates. Full pitfall analysis in docs/design/P2P_V2_COOLING_OFF.md.

Live on Sepolia (playground — testnet only, no real value)

A self-serve playground is deployed on Sepolia so anyone can try the whole flow end-to-end — it runs the v2 escrow, so the cooling-off rebate and pull-payouts are live there first. All source is verified on Etherscan; only key material stays in the untracked .env. Unaudited demo — never send real assets.

Try it: open /p2p (defaults to Ethereum mainnet), switch to Sepolia, hit the faucet to mint test tokens, then post or take an offer (a few offers are pre-seeded, including boosted ones to show ranking and one with a creator-set 2-day cooling window). Redeploy with cd loans && npx hardhat run scripts/deploy-playground-v2.js --network sepolia (addresses recorded in loans/deployments/sepolia-playground-v2.json; the retired v1 playground 0x3Ce4…1017 stays on-chain).

For AI agents (MCP)

npx -y @flashbank/mcp     # zero-config read-only MCP server, any MCP client

The repo ships a self-contained Model Context Protocol server (mcp/, published as @flashbank/mcp, listed in the official MCP Registry and on Glama) so agents can flashbank too: browse open P2P offers, get quotes, check flash-loan liquidity and fees — and, with an explicitly configured throwaway key, post/take/repay loans and use the Sepolia faucet. Reads need no configuration; mainnet writes are double-gated behind FLASHBANK_MCP_PRIVATE_KEY and FLASHBANK_MCP_ALLOW_MAINNET=true. Takes always pin the exact reviewed terms on-chain, and on v2 chains the tools quote vested fees and report cooling-off rebates. The whole lifecycle is proven by a live two-agent drill (npm run drill) that walks faucet → create → take → early repay (rebate verified) → cancel through two real MCP server instances on Sepolia. Details and the tool catalogue: mcp/README.md.

Repository layout

Each feature is a self-contained Hardhat project. The two never import each other's Solidity, so you can fork this repo, delete the feature you don't want, and the other still compiles, tests and deploys.

flashloans/           Flash-loan router feature — own contracts/, test/, scripts/, test-scripts/, hardhat.config.js
loans/                P2P term-loan feature — own contracts/, test/, scripts/, deployments/, hardhat.config.js
common/               Shared toolchain (hardhat.base.js) inherited by both features — do not delete
website/              Next.js front end (static export, deployed to flashbank.net) — showcases both features
mcp/                  Model Context Protocol server so AI agents can browse/quote/transact (see mcp/README.md)
docs/                 Documentation (see docs/README.md) — architecture, security, deployment, design
package.json          Thin root: installs the shared dependencies and runs both features' scripts

Want only one feature? Delete the other top-level directory:

rm -rf flashloans   # keep just the P2P term loans
# ...or...
rm -rf loans        # keep just the flash-loan router

common/ is shared by both and must stay. The website/ is a combined shopfront; if you drop a feature, also remove its page (website/src/pages/index.tsx for flash loans, website/src/pages/p2p.tsx for P2P) and its link in website/src/components/Nav.tsx.

A previous deposit-based design, FlashBankRevolutionary, predates the no-deposit Router. Its contracts and notes live under flashloans/ for historical context; the Router and P2P escrow are the current products.

Quick start

npm install            # installs the shared toolchain both features build against
npm run compile        # compile both features
npm test               # run both features' test suites

# work inside a single feature
cd flashloans && npx hardhat test
cd loans && npx hardhat test

# website
npm run website:dev    # local dev server on http://localhost:3000
npm run website:build  # static export

Dependencies are installed once at the repository root; each feature resolves Hardhat, the plugins and OpenZeppelin from there, so there is no per-feature npm install.

Tests

The Solidity suites cover the router (flash-loan flow, owner-fee accrual, dual control, validation) and the P2P escrow (lifecycle, time-based default, the three-tier fee model and boost, reentrancy, plus a randomised fund-conservation fuzz test).

npm test                            # both features
npm run test:flashloans             # router suite only
npm run test:loans                  # P2P suite only

Documentation

Browse docs/ for the full set:

• Architecture — overview, pool mechanics, gas analysis
• P2P design — P2P_LENDING_DESIGN.md, Lorrow compatibility
• Security — the live honest audit page (both features, candid: trust assumptions, what's tested, known limits), plus router audit notes, reentrancy analysis, dual-control runbook
• Deployment — guide, website, live networks

Vulnerability disclosure: SECURITY.md · Contributing: CONTRIBUTING.md · Changes: CHANGELOG.md

Disclaimers

Experimental, unaudited DeFi software. Smart contracts can have bugs; collateral values can move during a loan term; flash-loan profitability depends on market opportunities. Use at your own risk and do your own research.

License

MIT.