x402 — Pay-per-call APIs for VS Code

Browse the x402 bazaar, decode 402 Payment Required challenges, and pay per call for paid APIs and MCP tools in USDC or $THREE on Solana, or USDC on Base and other EVM chains, without leaving your editor. Powered by three.ws.

Install from the VS Code Marketplace, or run:

code --install-extension threews.vscode-x402

x402 is a protocol for developers and agents, not end users, so unlike a 3D viewer this is genuinely editor-native: the people wiring up paid endpoints and calling them live in VS Code.

Pay with $THREE on Solana

Choose $THREE in the x402.preferToken setting to prefer services that accept the three.ws ecosystem token.

• Symbol: $THREE
• Network: Solana
• Contract address: FeMbDoX7R1Psc4GEcvJdsbNbZA3bfztcyDCatJVJpump
• Payment scheme: x402 exact through @x402/svm

The extension only selects $THREE when the endpoint advertises that exact mint in its 402 challenge. It shows the token amount, network, paying address, and recipient before signing. Every $THREE payment requires explicit confirmation.

Features

• Bazaar sidebar — live list of paid x402 HTTP APIs and MCP tools, merged across every facilitator via the three.ws discovery proxy (/api/bazaar/list, /api/bazaar/search). Filter by type, price, and tag; full-text search.
• Inspect an endpoint — paste any URL and decode its 402 challenge: every accepted network, asset, scheme, price (in USD), and payTo, with the rail each accept settles on ([solana] / [evm]) and the one this wallet can satisfy flagged.
• Pay & call — make a real paid request and settle it on the right rail automatically: USDC or $THREE on Solana via the real @x402/svm exact scheme, or USDC on Base and other EVM chains via @three-ws/x402-fetch. The exact USD amount, token, and network are shown and confirmed before signing; a spending cap blocks anything above your limit. The response body and on-chain settlement receipt (tx hash) render inline.
• Two secure wallets — an EVM key and a Solana key, each stored only in VS Code SecretStorage (the OS keychain). Never in settings, never on disk in plaintext. The status bar shows both derived addresses.
• Scaffold a paid endpoint — generate a working api/x402/<slug>.js that follows the repo's canonical paidEndpoint() pattern, wired end-to-end from the first deploy.

Setup

1. Install the extension and open the x402 Bazaar view in the activity bar. Set the Bazaar discovery host to https://three.ws, or inspect a specific endpoint directly.
2. Set a wallet key for the rail you want to pay on:
   • x402: Set Solana Wallet Key — a base58 secret key (or JSON byte array) for a funded Solana wallet holding USDC and/or $THREE.
   • x402: Set EVM Wallet Key — a 0x + 64 hex key for a funded Base USDC wallet. Either or both; keys are stored in your OS keychain.
3. Browse or search the bazaar, open a service, and Pay & call.

Settings

The USD spending cap applies to USDC payments. A non-stable token such as $THREE is always shown in token units and always requires explicit confirmation because the 402 challenge does not provide a fiat conversion.

How payment works

The extension reads the 402 challenge and picks a payable requirement across both rails, honouring network and preferToken.

• Solana (solana:*): the real @x402/svm exact scheme signs an SPL transfer of the selected token (USDC or $THREE, mint FeMbDoX7R1Psc4GEcvJdsbNbZA3bfztcyDCatJVJpump) from your key and retries with the X-PAYMENT proof. This is the same buyer @three-ws/x402-mcp uses.
• EVM (eip155:*): @three-ws/x402-fetch signs a USDC EIP-3009 transferWithAuthorization on Base (or another EVM chain) and retries with the proof.

Either way the merchant settles on-chain and returns the work plus a settlement receipt, rendered inline with the token, network, and transaction hash. A service that only accepts a rail you have no key for is flagged, and the extension offers to set the matching wallet.

Development

npm install
npm run build        # bundle to dist/extension.cjs
npm run watch        # rebuild on change
npm test             # requirement selection, token rules, scaffold template

Press F5 in VS Code to launch an Extension Development Host.

See LICENSE. Source: nirholas/vscode-x402.