Smart Accounts on HPP
A plain wallet is a private key: whoever holds it can do anything, and every action costs gas in ETH. A smart account puts rules in code instead. On HPP that means a user can sign in with an email, send their first transactions without owning any ETH, and give an AI agent a budget it cannot exceed — enforced on-chain, revocable at any time.
HPP runs the whole ERC-4337 stack itself — bundler,
paymaster, and smart-account contracts — behind one endpoint, https://aa.hpp.io, and ships a
ready-to-use wallet on top of it.
Smart Accounts on HPP Mainnet are newly launched. Sponsored (free) operations are limited and may change, and there is no uptime guarantee yet. Start on HPP Sepolia, and use small amounts on Mainnet.
What you get
| Plain wallet (EOA) | Smart account on HPP | |
|---|---|---|
| Getting started | Install an extension, write down a seed phrase, buy ETH for gas | Sign in with email. Your address is ready in about five seconds |
| Gas | Every action needs ETH | A limited number of operations are covered by HPP; after that, gas is paid in USDC.e — no ETH in the wallet |
| Letting an AI agent pay | Hand over a key that can spend everything | Grant a limit ("up to 5 USDC.e, for 30 days"). The chain enforces it; revoke with one click |
| Several actions at once | One pop-up and one fee each | One signature, executed together or not at all |
Choose your path
👛 I want to use a wallet
| I want to… | Start here |
|---|---|
| send and receive USDC.e, pay x402 services | HPP Smart Wallet |
| let an AI agent (Claude, Cursor, …) pay from my wallet within a limit | Pay from an agent |
🛠️ I want to build with it
| I want to… | Start here |
|---|---|
| understand smart accounts, bundlers and paymasters first | How it works |
| create smart accounts and send transactions from my app | Quickstart |
| let my users transact without holding ETH | Gas sponsorship |
| give an agent or a backend limited, revocable permissions | Agent permissions |
| look up endpoints, contract addresses, limits | Reference |
| fix an error | Errors & troubleshooting · FAQ |
Networks
| HPP Mainnet | HPP Sepolia (testnet) | |
|---|---|---|
| Chain ID | 190415 | 181228 |
| Bundler + paymaster endpoint | https://aa.hpp.io/rpc | https://aa-sepolia.hpp.io/rpc |
| EntryPoint | v0.7 (SDK default, sponsorship); v0.8 self-paid only | same |
| Account | Kernel v3.3 — EIP-7702 (same address) or factory | same |
| Gas paid by | The account (ETH), HPP (sponsored), or the user in USDC.e | same |
| Gas sponsorship for your app | Apply on GitHub | Sandbox policy — apply on GitHub |
| Agent payments (ERC-7710) | ✅ | ✅ |
| Wallet | aa.hpp.io | aa-sepolia.hpp.io |
Build and test on HPP Sepolia first: everything on these pages works there with test USDC.e.
Get help
- Developers: hpp-io/hpp-aa-sdk issues — questions, bugs, sponsorship requests
- Wallet users: HPP Telegram
How it relates to x402
x402 is how an app or agent pays for an API call. Smart accounts change what the wallet is. The two meet in one place: a smart account can grant an agent a payment delegation (ERC-7710), and the agent then pays x402 services from the user's account — within the limit — without ever holding funds of its own.