Debit Llama - Crypto Subscriptions

Debit Lllama

Direct Debit Crypto Subscriptions infrastructure to create a circular AI Aget Economy

A subscription first alternative to x402 for agents

Link: https://debitllama.com
Deployed on Arbitrum Sepolia Testnet
Documentation: https://debitllama.gitbook.io/debitllama

Supports USDG from Paxos and USDC from Circle and ETH

Explanation
DebitLlama is a protocol and a service composed of many layers. The goal of the service is to implement direct debit subscriptions using accout abstractions. The service handles checkout flow for sold subscription items, provides a UI for Accunt Abstraction and helps manage payment intents which are immutable zero-knoledge proof based invariants usable by merchants to pull payments directly from customers.

Tech Stack

Circom

The zero-knoledge circuits are implemented uisng circom and they provide the foundation to the service. They help provide immutable subscription parameters and account abstraction.
The cryptography is inspired by tornado cash crypto notes but does not provide privacy, instead subscription payments were implemented for direct debit.
Read about the circuits here
Source code is here

Smart Contracts

The contracts are implemented in solidity and they provide the direct debit contract
The contract is then used to implement account abstraction. You can see the docs here
Virtual accounts and Connected Wallets are implemented with each providing a different UX.
Direct debit transactions are possible from the accounts by using a zero-knowledge proof that encodes the subscription parameters. The proof is replayable until the subscription has been completed. It includes a max debit amount, interval of payments, time between payments etc.

The virtual account is a smart contract deposit account while the connected wallet allows spending an ERC-20 token using ERC20 approvals

Intent Solvers

The account abstraction transactions are processed as Intents (payment intents) which are then processed by merchants automatically by running an intent solver. The documentation here has a link to the source code.

DebitLlama.com service
The core service is a database application and front-end to access smart contract accounts. It helps users manage Debit Items which then later can pass through the checkout and sold for subscriptions. The subscriptions can be cancelled on-chain via the front-end provided and the account balance deposits are also controlled there.

MCP server
Docs

A new agentic account type has been added to debitllama which allows delegating control over spending to an agent via the MCP server that interacts with the debitllama service API
New accouts can be created using the CLI and then the deposits controlled uisng the dashboard UI. It is a full fledged MCP server compatible with any agentic flow and allows agents to create subscription agreements with each other autonomously.

Work in progress
Smart contracts - circuits progress 100% Fully developed and tested
Intent Solvers - progress 100% Fully developed and tested

DebitLlama Service - Undergoing maintenance for the hackahton, some service interruptions are normal.

Debitllama MCP - Undergoing testing after agentic development, changes are expected even during the hackathon.
Smart contract addresses:
Arbitrum SEPOLIA
Verifier contract is deployed to 0x26Cb79a592dC3F2F4e588Ed19A5A5314779fe80E

Virtual Accounts contract is deployed to : 0x5586938a2fC4489661E868c5800769Fb10847fC5

Connected Wallets contract is deployed to: 0x3Cad43A3038F0E657753C0129ce7Ea4a5801EC90

Arbirum MAINNET

Verifier contract is deployed to 0x26Cb79a592dC3F2F4e588Ed19A5A5314779fe80E

Virtual Accounts contract is deployed to : 0x5586938a2fC4489661E868c5800769Fb10847fC5

Connected Wallets contract is deployed to: 0x3Cad43A3038F0E657753C0129ce7Ea4a5801EC90

NOTE: The UI only provides access to testnet for now. but mainnet is already deployed.