# x402 paid agent starter (TypeScript and Python)

Two starter templates for a paid agent listed on LAX (https://lax.kognai.ai), one per folder, each usable on its own:

| | TypeScript | Python |
|---|---|---|
| Paid route | `typescript/src/app.ts`: `createApp({price, payTo, network, facilitator, description?})`, a web standard `fetch` handler (Node, Hono, Bun, workers) | `python/app.py`: `create_app(...)`, FastAPI |
| LAX offer | `typescript/lax-offer.json` | `python/lax-offer.json` |
| Listing script | `typescript/src/list.ts` `listOffer({offer, registryUrl?, fetch?, pay})` and `scripts/list.ts` | `python/list_offer.py` |
| Tests | `npm test` (node:test via tsx) | `pytest` |

Both speak x402 version 1, exact scheme, USDC on Base (`base`) or Base Sepolia (`base-sepolia`):

- `GET /paid` without `X-PAYMENT` answers 402 with `{x402Version: 1, error, accepts: [requirements]}`. The USDC asset is `0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913` on base and `0x036CbD53842c5426634e7929541eC2318f3dCF7e` on base-sepolia, and `maxAmountRequired` is in atomic units (6 decimals).
- With `X-PAYMENT` (base64 JSON) the app checks scheme and network, asks the facilitator to verify, then to settle, and only then does the work. It answers 200 with `X-PAYMENT-RESPONSE` (base64 JSON of the settlement). A payment that does not verify or settle gets 402, and the work is not done.
- `GET /health` is free.

The facilitator comes from the configuration: an object with `verify` and `settle`, or a URL (default `https://x402.org/facilitator`, which settles x402 v1 on base-sepolia; `https://facilitator.payai.network` settles v1 on base).

On-chain proof (21 October 2026): each starter settled one real paid call of 0.01 test USDC on Base Sepolia through the x402.org facilitator: TypeScript https://sepolia.basescan.org/tx/0x352aa808ef460fdaf8de6a9ba8a0e5bac7f2cf7b26c426f6b9440cd0de13cacf and Python https://sepolia.basescan.org/tx/0xef8fb6cd9f8f6c4d8e0552d21bd7863743392371b13f64efa7762f6dbe93c648. Details and how to reproduce: [PROOF.md](PROOF.md).

Keys are read by the caller from the environment (`LAX_PAYER_KEY`, `PAYER_KEY`) and never logged. Every payment script has a spend cap (`MAX_FEE_ATOMIC`, default 10000 = 0.01 USDC).

Derived in part from the MIT AgentGate x402 service (https://github.com/agentgate-builder/agentgate). MIT licence.