Canonical builder entrypoint

I have an agent that sends EVM transactions

Before your EVM agent broadcasts a transaction, run Nishvault as a paid pre-send risk guard.

This page deliberately compresses the decision: wrap sendTransaction, run one unpaid 402 Payment Required, then do one paid guard check only if the live route looks correct.

Trigger the unpaid 402 first Open this page from nishvault.com

I already have one transaction payload

Your problem is one concrete send path and you want a guard right before broadcast.

  • Use /integrations.
  • Fastest command: npx --package nishvault-preflight-buy nishvault-guard-tx -- --seller-url https://api.nishvault.com --to 0x2222222222222222222222222222222222222222 --data 0x --value 0x0

I use viem, ethers, or my own sendTransaction wrapper

Your problem is fitting a paid preflight directly into an existing wallet client or send primitive.

  • Use /integrations.
  • Look for createViemPreflightGuard, createEthersPreflightGuard, createEip1193PreflightGuard, or createGuardedTransactionSender.

I run an MCP or tool-calling agent

Your problem is stopping the agent between “tool picked send” and “wallet actually sent”.

I drain queue or cron jobs

Your problem is preventing a worker from flushing risky transactions blindly.

Shortest trust path

  1. Confirm your agent has a real sendTransaction or broadcast point.
  2. Open /first-unpaid-402 and confirm the route returns a real unpaid challenge.
  3. Use /integrations to put the guard immediately before the send primitive.
  4. If the route looks correct and the need is real, use /quickstart for one paid Base mainnet preflight.

Why this page exists

The product already had trust, examples, recipes, and proof pages. What was missing was one discoverable decision surface that maps real runtime shapes to the right public entrypoint without asking the builder to infer it.

This surface now separates safe demo proof from live revenue. The public API is configured for eip155:8453, $0.01, and real USDC payment.

X402_BUYER_PRIVATE_KEY=0xYOUR_BASE_MAINNET_BUYER_KEY npm exec nishvault-guard-tx -- --seller-url https://api.nishvault.com --to 0x2222222222222222222222222222222222222222 --data 0x --value 0x0