Nishvault trust landing for EVM agent builders
This is the root-domain trust surface for Nishvault. The live paid API remains https://api.nishvault.com.
Before your EVM agent broadcasts a transaction, run Nishvault as a paid pre-send risk guard.
The core promise is simple: do not let your agent send blind. See one live unpaid 402 first, then move to exactly one guard install step if the route looks real.
Exact host handoff
https://nishvault.comis the trust and narrative host./go/first-check?from=root-trust-landingis the root-host bridge click for the first check.https://api.nishvault.com/.well-known/x402exposes the live route, price, network, and pay-to wallet on the API host.https://api.nishvault.com/first-unpaid-402?autorun=1#live-first-checkruns the no-wallet unpaid challenge on that same API host.https://api.nishvault.com/integrationsis the guard install surface only after the unpaid result looks correct.
Start here
Your first job is not to install anything or pay yet. Your first job is to prove the protected route can stop blind sends with one real payment_required on the canonical first-check surface.
Run the canonical unpaid 402 first
In plain terms: click through to /first-unpaid-402, confirm the live 402, then copy one guard command only if the route looks correct.
Workflow-first entrypoints after that proof: viem wrapper, ethers signer wrapper, and queued agent step guard.
The 402 worked. Copy one guard command next.
Single next step: if your agent has a transaction shape, copy this command and put it in the exact slot where your runtime would otherwise call sendTransaction.
npx --package nishvault-preflight-buy nishvault-guard-tx -- --seller-url https://api.nishvault.com --to 0x2222222222222222222222222222222222222222 --data 0x --value 0x0
The trust host is only here to earn the first cheap proof. After that, stay on one paid next step: open the launch gate, keep the same route, network, and price, and do not branch into extra docs first.
Stop here if the unpaid result looked wrong
If the browser check does not return a real payment_required response, do not continue to wallet setup or paid retries yet.
Advanced / after-first-check paths
The root host explains why Nishvault exists. The live x402 route and paid buyer flow stay on https://api.nishvault.com. Use these only after the first 402 is real.
Browser unpaid 402 demo
No wallet needed for the first proof step. Click once to send the example payload from your browser and inspect the live payment_required response. Do not fund a buyer wallet unless this exact unpaid challenge looks correct.
{
"chainId": "0x2105",
"from": "0x1111111111111111111111111111111111111111",
"to": "0x2222222222222222222222222222222222222222",
"data": "0x",
"value": "0x0"
}
Click the button to run one live unpaid challenge against https://api.nishvault.com/simulate/transaction-preflight.
- Open the dedicated first-check page Stay on the smallest no-wallet trust surface.
- Open builder start-here Choose the right viem, MCP, queue-worker, or one-off send path before paying.
- Open integrations See the workflow-first viem, ethers, EIP-1193, and agent-step entrypoints.
- Open discovery metadata Inspect the raw `/.well-known/x402` surface directly.
Agent-builder positioning • Integrations • Start here • How it works • Proof
Mark this browser as owner traffic if you are testing the funnel yourself.