# x402 v2 Launch: Easier Payments for AI Agents *The Next Step in HTTP 402 Micropayments - Multichain, MCP, A2A Transports* By [Base Korea 대한베이스](https://paragraph.com/@daehan_base) · 2025-12-16 x402, x402_v2, x402_on_base, daehanbase --- On December 11th, x402 v2 was released. This is a major upgrade to HTTP-native micropayments. This post covers the key changes in v2 and recent updates to the awesome-x402-on-base repository. > **Full Spec**: [x402 v2 Protocol Specification (Korean)](https://github.com/Daehan-Base/awesome-x402-on-base/blob/main/docs/korean/x402-v2-specification.ko.md) | [Official Spec (English)](https://github.com/coinbase/x402/blob/main/specs/x402-specification-v2.md) * * * **What's New in v2** -------------------- * **HTTP Headers**: `X-PAYMENT` → `PAYMENT-SIGNATURE`, `PAYMENT-REQUIRED` * **Network Notation**: `base-sepolia` → `eip155:84532` (CAIP standard) * **Chain Support**: Single chain → Multichain (Base, Solana, Polygon, etc.) * **Transports**: HTTP only → HTTP, MCP, A2A * **Sessions**: None → Wallet-based session support ### **Multichain Support (CAIP Standard)** Network notation now follows the [CAIP standard](https://chainagnostic.org/). Instead of `base-sepolia`, you use chain IDs like `eip155:84532`. This allows a single spec to support multiple chains including Base, Solana, and Polygon. ### **MCP Transport for AI Agents** **Model Context Protocol (MCP)** transport has been added. When AI agents call paid tools on MCP servers, they send payment information in the `_meta` field of JSON-RPC messages. This enables scenarios where MCP clients like Claude or Cursor automatically pay while using tools. For example, paying $0.01 per call when invoking a financial analysis tool. ### **A2A (Agent-to-Agent) Transport** Based on [Google's A2A Protocol](https://github.com/google/A2A), agents can pay each other directly. Agents declare x402 support in their AgentCard and track payment flows (`payment-required` → `payment-submitted` → `payment-completed`) through the Task state machine. ### **Other Changes** **Plugin Architecture** v1 had a monolithic SDK structure, but v2 has transitioned to a modular plugin architecture. You combine independent plugins by chain (`@x402/evm`, `@x402/svm`) and payment scheme. Adding new chains or payment methods doesn't require touching existing code. **Session Management (Sign-In-With-X)** Instead of sending a payment signature with every request, you can log in once with your wallet and reuse a session token. The `@x402/paywall` package provides this feature, significantly improving UX for repeated API calls. **Dynamic Routing (payTo)** In v1, the payment recipient was fixed in server settings, but in v2, you can dynamically specify the `payTo` address per request. This is useful for marketplace scenarios where direct payments to multiple sellers are needed. **Discovery API (Bazaar)** A feature for automatically discovering API endpoints that support x402. Agents can search for resources with conditions like "financial data APIs under $0.01". It's essentially a paid API marketplace infrastructure. **Enhanced Security** Support for smart contract wallet (ERC1271) and counterfactual wallet (ERC6492) signature verification. Account Abstraction wallet users can now use x402 payments. * * * **awesome-x402-on-base Updates** -------------------------------- The repository structure has been reorganized for v2. ### **Directory Structure Changes** awesome-x402-on-base/ ├── external/x402/ # Official x402 (submodule) ├── docs/korean/ │ ├── v1/examples/ # v1 Python example guides (4) │ ├── v2/ # v2 docs (in progress) │ └── x402-v2-specification.ko.md # v2 spec Korean translation ├── examples/ │ ├── v1/ # v1 examples (ap2-demo-coffee-shop) │ └── v2/ # v2 examples (coming soon) └── resources/ # Korean community links ### **Key Additions (12/16)** * **x402 v2 Protocol Spec Korean Doc** - Full translation of HTTP/MCP/A2A transports, payment schemes, Facilitator API * **Bilingual Support** - Korean/English versions for all READMEs * **CONTRIBUTING.md** - Contribution guide * **GitHub Issue Templates** - For feature/example suggestions ### **Path Changes** Official example paths have changed with v2 release: # Before (v1) external/x402/examples/python/clients/requests # After (v1 legacy) external/x402/examples/python/legacy/clients/requests Korean docs have also moved: # Before docs/korean/examples/*.ko.md # After docs/korean/v1/examples/*.ko.md * * * **Getting Started** ------------------- ### **1) Clone & Sync Submodule** git clone --recursive https://github.com/Daehan-Base/awesome-x402-on-base.git git submodule update --init --recursive ### **2) Read v2 Spec** # Korean v2 spec docs/korean/x402-v2-specification.ko.md # Official spec (English) external/x402/specs/ ### **3) Try v1 Examples (Python)** cd external/x402/examples/python/legacy/clients/requests cp .env-local .env # Add PRIVATE_KEY to .env uv sync && uv run python main.py Korean guide: `docs/korean/v1/examples/python-requests-client.ko.md` * * * **Conclusion** -------------- x402 v2 is an upgrade optimized for AI agent payments. With MCP/A2A transports, the flow of agents paying while using tools has become much more natural. Experience micropayments firsthand with the Base + x402 v2 combination. * * * **Reference** ------------- * [awesome-x402-on-base](https://github.com/Daehan-Base/awesome-x402-on-base) * [x402 v2 Launch Announcement](https://x402.org/writing/x402-v2-launch) * [Official x402 Repo](https://github.com/coinbase/x402) * [x402 v2 Spec (Korean)](https://github.com/Daehan-Base/awesome-x402-on-base/blob/main/docs/korean/x402-v2-specification.ko.md) --- *Originally published on [Base Korea 대한베이스](https://paragraph.com/@daehan_base/x402-v2-launch-easier-payments-for-ai-agents)*