@tempwallet/sdk — v0.1.0

Ephemeral Wallet SDK for Ethereum & EVM chains
Create temporary, single-use wallets with built-in safety (TTL, one-time semantics, sweep helpers, Safe builders).
Designed for one-time payments, demo sessions, disposable accounts, and secure checkout flows.

⚡ No servers. No custody. No contracts. Just pure client-side helpers.

🎯 Why TempWallet SDK?

Developers often struggle when building short-lived wallet flows for payments, access, or testing:

• ❌ Reusing normal wallets is insecure (private key exposure, replay risks)
• ❌ Building sweeps & gas buffers from scratch is error-prone
• ❌ Safe integrations require verbose boilerplate
• ❌ Permit2 / EIP-712 signing flows are tedious to set up

👉 TempWallet SDK solves this by giving you:

• 🪪 Ephemeral wallets — single-use semantics with TTL enforcement
• ⛽ Gas helpers — estimate, add margin, and sweep correctly with safety buffers
• 🔒 Error-proof API — typed errors for expired or reused wallets
• 🛡 Safe builders — ready-to-use payloads for Safe Core SDK
• 🧹 Sweep utilities — clean up leftover ETH after payments
• 🪙 Permit2 skeletons — plug-and-play flows for token approvals

Built on ethers v6. Type-safe. Tree-shakeable. Zero infra required.

📦 Installation

npm install @tempwallet/sdk ethers

Requires: ethers v6.13.0+ (peer dependency)

🚀 Quick Start

One-Time ETH Checkout

import { createTempWallet, buildSweepTx } from "@tempwallet/sdk";
import { parseEther } from "ethers";

// 1. Create a temporary wallet
const wallet = createTempWallet({ ttl: 3600, label: "checkout-session-123" });
console.log("Ephemeral address:", wallet.address);

// 2. Send ETH payment
const txHash = await wallet.sendTransaction({
  providerUrl: process.env.RPC_URL!,
  to: "0xRecipient",
  value: parseEther("0.1"),
});
console.log("Payment sent:", txHash);

// 3. Sweep leftover funds (optional)
const sweepTx = await buildSweepTx({
  fromAddress: wallet.address,
  to: "0xMainWallet",
  providerUrl: process.env.RPC_URL!,
  gasLimitBuffer: parseEther("0.001"),
});

📚 API Overview

createTempWallet(opts?)

Creates an ephemeral wallet with TTL & one-time semantics.

const wallet = createTempWallet({ ttl: 1800, label: "demo" });

wallet.sendTransaction(input)

Sends a transaction with single-use enforcement.

Throws:

• ExpiredSessionError if TTL passed
• AlreadyUsedError if reused

buildSweepTx(input)

Builds a sweep transaction to move all ETH safely with gas buffer.

estimateTotalCostWei(input) / estimateWithMarginWei(input, marginBps)

Gas cost calculators with optional safety margin.

buildSafePayment(params) / buildSafeSweep(params)

Ready-to-use payloads for Safe Core SDK.

buildPaymentURI(address, wei?)

Generates EIP-681 payment URIs (ethereum:0x...).

🔥 Real Use Cases

1. Crypto Checkout
   Accept ETH payments with ephemeral wallets that auto-expire & sweep.

2. Demo / Sandbox Accounts
   Let users play in your dApp without touching their main wallet.

3. Disposable Session Keys
   Issue one-time wallets for gated content or temporary access.

4. Safe Transactions
   Build Safe-compatible payment payloads in 1 line.

5. Permit2 Token Flows
   Generate typed skeletons for Permit2 signatures.

⚠️ Typed Errors

import { ExpiredSessionError, AlreadyUsedError } from "@tempwallet/sdk";

try {
  await wallet.sendTransaction(tx);
} catch (err) {
  if (err instanceof ExpiredSessionError) {
    console.log("Wallet expired — create new one");
  }
}

🔒 Security Best Practices

✅ Generate keys only client-side
✅ Use secure storage (memory/session only for TTL)
✅ Always sweep leftovers
✅ Enforce TTL (default 1h)
❌ Never reuse ephemeral wallets
❌ Don’t use in production without sweep fallback

🗺 Roadmap

• [🚧] ERC-20 & ERC-721 sweep helpers
• Batch transaction builder
• Auto RPC gas estimator
• Multi-chain presets (Optimism, Base, Polygon, Arbitrum)
• Recovery flows (optional seed phrase support)

🤝 Contributing

Contributions welcome!
Check CONTRIBUTING.md.

📄 License

MIT — see LICENSE

💸 Support

If this SDK saved you time or you like the philosophy of zero infra helpers, feel free to send a tip ❤️:

ETH / USDC: 0x687848FC782Dc20edCa4b535f27fB4b1B398a305

🔗 Links

• Docs
• Issues
• Security
• Changelog
• Contact

Ephemeral wallet SDK, temporary Ethereum wallet, one-time crypto payments, secure ETH checkout, Safe transaction builder, Permit2 helper, sweep ETH balance, gas estimation utils, client-side EVM flows.