What is a402 and how do I integrate it?

a402 extends HTTP-402 so your server can challenge a paid request, verify a machine payment, then release. Drop middleware, price endpoints, and use SDK pay()/verify(). Flow: request → 402 → pay → verify → release.

How do I add stablecoin payments to my app (Typescript/Python/Go)?

Use Beep’s SDK or HTTP APIs to auto-handle 402: on challenge, pay, verify receipt, retry; returns JSON receipt.

How do I monetize MCP tools per call?

Wrap tool routes with 402 middleware; issue challenge; on receipt verify → release; optional dual-hop split to platform/provider.

How do I mix subscriptions with micropayments?

Baseline monthly plan + metered per-call/per-token gated by a402; settle instantly, no pre-funding.

How do I earn yield while processing payments?

Route balances to Agentic Treasury where yield streams in real time, offsetting or beating fees ("negative-fee").

build agent payments

MCP-PAY

Per-call payments for MCP tools

Add x402 paywalls to MCP tools, unlock instant settlement with zero fees

build agent payments

Chain-agnostic protocol
Instant settlement
Cryptographic receipts
Yield-share option
Dual-hop payouts

For agents.

Call tool, handle 402 challenge, pay, resend with receipt, get output.

For merchants.

Set price, challenge user, verify receipt, release output, settle instantly.

An interactive walkthrough

This interactive diagram demonstrates how our SDK facilitates a per-API request payment flow. Use the buttons below to navigate through each step of the process, from the initial request to the final confirmation.

Node Quickstart (47s avg)

Replace “summarize” with any tool name, price as needed for per token/run/second. Try MCP-PAY in your stack in under one minute.

import { a402 } from “@beep-it/a402”;
import { mcp } from “@beep-it/mcp-pay”;
app.use(a402({ treasuryId: process.env.TREASURY_ID }));
mcp.tool(“summarize”, async (req, res) => {
    const price = { amount: “0.10”, asset: “USDC”, chain: “sui” };
    const ok = await a402.verifyOrChallenge(req, res, price);
    if (!ok) return;
    const out = await summarize(req.body.text);
    return res.json({ receipt: res.locals.receipt, result: out });
});

import { a402 } from “@beep-it/a402”;
import { mcp } from “@beep-it/mcp-pay”;
app.use(a402({ treasuryId: process.env.TREASURY_ID }));
mcp.tool(“summarize”, async (req, res) => {
    const price = { amount: “0.10”, asset: “USDC”, chain: “sui” };
    const ok = await a402.verifyOrChallenge(req, res, price);
    if (!ok) return;
    const out = await summarize(req.body.text);
    return res.json({ receipt: res.locals.receipt, result: out });
});

Live $0.01 Refund Demo

Test MCP-PAY: run live $0.01 USDC sandboxes on SUI. Receive cryptographic receipt, verify and automatically refund—ideal for CI, demos, and monitoring.

Example curl:
curl -s https://api.beep.it/mcp/challenge -H ‘Content-Type: application/json’ -d ‘{“tool”:”summarize”,”price”:{“amount”:”0.01”,”asset”:”USDC”,”chain”:”sui”}}’
Then verify & release:
curl -s https://api.beep.it/mcp/verify -H ‘Content-Type: application/json’ -d ‘{“receiptId”:”<id>”}’

a402 vs x402 table

Topic

MCP-PAY (a402)

x402

Chain stance

Chain-agnostic

Specific

AuthZ/ID

Built-in

Varies

Micros

Channelized/multi-chain

Lacks channels

Receipts

Signed, cryptographic

Sometimes

Marketplace

Dual-hop split, instant

Most lack dual-hop.

How do I add a paywall to my MCP tool?

Install SDK, set price, wrap tool with verifyOrChallenge. Works for per run, token, or second.

How is MCP-PAY different from x402/Stripe Tempo?

a402 is chain-agnostic with built-in auth and micro-flows. MCP-PAY meters with receipts and instant settlement.

What does “zero-fee” mean?

Zero-fee means that with mcppay, you pay no transaction toll fees for agent-to-agent payments—unlike traditional platforms like Stripe, which charge a percentage or flat fee per transaction. We’ve built a zero-fee model inspired by innovative payment networks, eliminating costly intermediaries to maximize your value. Whether it’s crediting AI agents or managing tokenized transactions, you keep more of what you earn, aligning with the future of a frictionless, trust-based economy

Which chains and assets are supported?

Sui-first for fast jobs; a402 is chain-agnostic. More chains and assets coming soon.

How do cryptographic receipts work?

Each payment returns a signed receipt—amount, chain, tool, proof. Use for bids, audits, and refunds.

Can I price by token, second, or request?

Yes—support per run, per token, per second/minute for streaming media, or hybrid. Use the price as you see fit.

Does this work with OpenAI, LangChain, MCP?

Yes, wrap tool calls via verifyOrChallenge. Marketplace: each run metered, dual-hop splits recorded.

How do I handle refunds, retries, or timeouts?

Use sandbox for easy refunds, guidance for retry/timeouts. No output if verify fails; receipts log all attempts.

Do I need KYC/AML or custodial setup?

Beep is non-custodial. KYC/AML can be added via partners depending on use case.

Can I split a basket into multiple payouts?

Yes—dual-hop supports splits for platform, creator, supplier. Example: $0.20 divides by share config.

How do I migrate from x402?

Follow the migration guide. Most flows are compatible via agent path and receipt verification.

Where can I see more sample apps?

Check the Examples section for SDK patterns, open source templates, and demos.

Get the SDK

Start using MCP-PAY in minutes.

View the developer docs

Beyond EVM

SUI-first; requests abstracted from settlement. Example: Chain A buyer to Chain B provider.

Built-in identity

KYA powered agent to agent payments

Reputation-ready

Empowering agents with trust-based credit

PRODUCTS

Agentic yield

Beep pay

MCP-pay

Resources

Docs

beep labs

Agent trader : Grand Prix

Join us on discord

Beep is not a bank, financial institution or a digital asset custodian.

Beep is a financial technology platform that enables eligible businesses to establish a self-custodied digital asset account and conduct transactions using stablecoins through the account.

Balance information denominated in fiat currency is for informational purposes only.

Stablecoins function as claims on the stablecoin issuer for a fixed amount of underlying fiat currency.

Beep is not a stablecoin issuer, does not make any promise (and does not have any obligation) to redeem stablecoins.

Beep does not hold any balance on behalf of its business customers and does not pay interest on digital asset balances.

Eligible business customers may earn rewards from beep based on their use of the beep services and the self-custodied digital asset account.

Yield is variable and not guaranteed. DeFi carries smart-contract and protocol risks. Review docs, your jurisdiction’s regulations before using Beep. Not investment advice.