# Unreadable quote: `/t/malformed`

> A 402 whose PAYMENT-REQUIRED header is not valid base64 JSON. A free public x402 test endpoint: Fail with a clear parse error. Do not crash, hang or sign a payment.

|  |  |
| --- | --- |
| Endpoint | `GET https://x402testendpoint.com/t/malformed` |
| Kind | trap: a correct buyer does not pay |
| Payment scheme | `exact` |
| Quoted price | none readable |
| Networks | Base Sepolia (testnet) (default), Solana Devnet (testnet) |
| Cost to you | Nothing. Test USDC has no value. |

## What the seller does

A 402 whose PAYMENT-REQUIRED header is not valid base64 JSON.

## What a correct buyer does

Fail with a clear parse error. Do not crash, hang or sign a payment.

## Why test this

Proxies truncate headers and sellers ship bugs. A client must treat an unreadable quote as an error, never as free access or a reason to guess.

## Run it

See the quote without paying:

```bash
curl -i https://x402testendpoint.com/t/malformed
```

Then point your own client at it, or use the official one:

```ts
import { x402Client, x402HTTPClient } from "@x402/core/client";
import { ExactEvmScheme } from "@x402/evm/exact/client";
import { privateKeyToAccount } from "viem/accounts";

const account = privateKeyToAccount(process.env.BUYER_KEY);
const core = new x402Client().register("eip155:84532", new ExactEvmScheme(account));
const http = new x402HTTPClient(core);

const first = await fetch("https://x402testendpoint.com/t/malformed");
const quote = http.getPaymentRequiredResponse((h) => first.headers.get(h));
const headers = http.encodePaymentSignatureHeader(await core.createPaymentPayload(quote));
const paid = await fetch(first.url, { headers });
console.log(paid.status, paid.headers.get("x-test-verdict"));
```

The wallet needs test USDC on Base Sepolia (testnet) for scenarios that settle. Circle's faucet at https://faucet.circle.com provides it.

## Other networks

Add a `network` parameter to run the same scenario elsewhere:

| Network | URL | Notes |
| --- | --- | --- |
| Solana Devnet (testnet) | `https://x402testendpoint.com/t/malformed?network=solana-devnet` | Test USDC on Solana Devnet. Register `ExactSvmScheme` from `@x402/svm/exact/client`. |

Traps run on test networks only. A signed mainnet payment is spendable by whoever holds it until it expires, so this site does not invite one for a seller built to misbehave.

## What you will see

This is a trap: there is no successful payment. A correct client stops without sending a `PAYMENT-SIGNATURE` header, or stops retrying, and reports the problem to its caller.

If your client pays what it should have refused, the endpoint answers HTTP 400 with `x-test-verdict: fail` and a `reason` in the JSON body. The payment is not verified, settled, stored or logged, so no funds move.

## How the official client behaves

`@x402/core` 2.31 with default settings: Throws "Invalid payment required header".

## Related errors

- [`Invalid payment required header`](https://x402testendpoint.com/errors/invalid-payment-required-header): The client could not read the seller's quote.

## Other scenarios

- [Standard payment](https://x402testendpoint.com/scenarios/ok) (pay)
- [Pick the supported option](https://x402testendpoint.com/scenarios/choose) (pay)
- [Slow seller](https://x402testendpoint.com/scenarios/slow) (pay)
- [Pay up to a maximum](https://x402testendpoint.com/scenarios/upto) (pay)
- [Absurd price](https://x402testendpoint.com/scenarios/overpriced) (trap)
- [Price changes after you pay](https://x402testendpoint.com/scenarios/price-bump) (trap)
- [Unsupported network only](https://x402testendpoint.com/scenarios/wrong-network) (trap)
- [Quote without a recipient](https://x402testendpoint.com/scenarios/missing-fields) (trap)
- [Seller never delivers](https://x402testendpoint.com/scenarios/always-402) (trap)

Source: https://x402testendpoint.com/scenarios/malformed