What is the difference between MnemoPay and x402?

x402 is an open settlement protocol (HTTP 402 + on-chain payment) governed by the x402 Foundation co-founded by Coinbase and Cloudflare. It uses USDC on Base as the default rail. MnemoPay is the trust layer above any rail — it produces Ed25519-signed receipts, runs an agent FICO credit score, holds escrow, enforces HITL approval, and emits EU AI Act Article 12 audit bundles. They compose: x402 settles the payment, MnemoPay records and governs it.

Can I use MnemoPay and x402 together?

Yes. MnemoPay ships an X402Rail adapter in the SDK. Every x402 settlement automatically writes a signed entry to the MnemoPay audit chain, attaches to the agent's reputation, and runs through FiscalGate budget enforcement. The on-chain transaction is the source of truth for the money move; the MnemoPay receipt is the source of truth for the policy decision and audit.

When should I use x402 alone vs MnemoPay?

Use x402 alone when you only need on-chain pay-per-API-call between agents and merchants and you don't care about an audit trail, reputation, or budget caps. Add MnemoPay when you need any of: a portable agent identity, an audit bundle for compliance (EU AI Act Article 12, SOC2, ISO 42001), escrow with dispute windows, HITL approval, or a spend policy that follows the agent across rails.

Is x402 the only rail MnemoPay supports?

No. MnemoPay supports Stripe, Paystack, Lightning, Stripe Multi-Party Payments, x402 USDC on Base, and Google AP2 through a single SDK. The receipt and FICO surface is identical across rails — the agent's reputation and audit chain are portable, the rail underneath is swappable.

Which is cheaper, x402 or MnemoPay Pro?

x402 has no platform fee — you pay only the on-chain gas (USDC on Base, typically sub-cent). MnemoPay's self-hosted SDK is free forever under Apache 2.0; the managed Pro tier is $49/month and adds hosted FICO scoring, audit-bundle generation, and reputation portability. They are not substitutes — x402 is a rail, Pro is a managed service for everything above the rail.

Comparison · 2026

MnemoPay vs x402

x402 moves money on-chain. MnemoPay produces the receipt above the rail. They compose. Side-by-side breakdown of what each does, when to use which, and the 40-line code snippet to run both at once.

tl;dr

x402 is a settlement protocol — HTTP 402 + on-chain USDC on Base. Governed by the x402 Foundation, co-founded by Coinbase and Cloudflare in 2026.

MnemoPay is the trust layer above any payment rail — Ed25519-signed receipts, agent FICO (300-850), escrow, HITL approval, Article 12 audit chain, portable reputation.

Not substitutes. x402 moves the money. MnemoPay records the decision. The MnemoPay SDK ships an X402Rail adapter that wires the two in 4 lines.

Feature compare

Capability	x402	MnemoPay
What layer	Settlement rail	Trust + governance layer
Default money rail	USDC on Base	Stripe, Paystack, Lightning, x402, Google AP2
On-chain settlement	Yes (Base L2)	Optional (via X402Rail or LightningRail)
Off-chain rails	No	Yes — Stripe + Paystack
Signed receipts	Tx hash on-chain	Ed25519 + Merkle chain off-chain, on-chain anchor optional
Agent FICO score	No	Yes — 300-850, payment + behavior weighted
Escrow	Smart-contract patterns	Yes — built-in, with refund / dispute window
HITL approval	No	Yes — charge_request / charge_approve
EU AI Act Article 12	Tx history serves as log	Built — exportable audit bundle
Spend policy	Per-call price	FiscalGate budgets + per-merchant caps + categories
License	Apache 2.0	Apache 2.0
SDK install	x402 client libs	`npm install @mnemopay/sdk`
Production traction	165M+ tx (2026)	1.1k+ npm weekly, 40 tools on Smithery
Best when	Pure pay-per-call between agents + merchants on web	Audit trail, reputation, multi-rail, compliance, escrow

Use them together

The cleanest pattern in 2026 is x402 underneath, MnemoPay on top. The on-chain transaction is the money truth; the MnemoPay receipt is the policy + governance truth.

import MnemoPay, { X402Rail } from "@mnemopay/sdk";

// agent identity + rail
const agent = MnemoPay.quick("my-agent");
await agent.useRail(new X402Rail({ chain: "base", asset: "USDC" }));

// agent pays a merchant per API call
const tx = await agent.charge(0.05, "GET /forecast");
await agent.settle(tx.id);

// receipt is signed, FICO updates, audit chain extends
const bundle = await agent.exportBundle({ format: "article12" });

4 lines of integration. x402 handles the money. MnemoPay handles the receipt + FICO + audit bundle.

When to use which

Use x402 alone

Pay-per-API call between agents on the open web. No audit requirement. No reputation portability needed. Crypto-native team. USDC settlement is acceptable.

Add MnemoPay

EU operations (Article 12). Need agent FICO for cross-platform trust. Need escrow with dispute window. HITL approval for high-value charges. Multi-rail (Stripe + Paystack + x402 + Lightning). Compliance evidence beyond an on-chain hash.

FAQ

Is x402 a competitor to MnemoPay?

No. x402 is a settlement protocol. MnemoPay is a trust + governance layer. They sit at different points in the stack. x402 is what we use when the rail is on-chain; the MnemoPay SDK ships an X402Rail adapter specifically to compose with it.

Why would I add MnemoPay if x402 already gives me a tx hash?

A tx hash tells you money moved. It doesn't tell you: why it moved, who approved it, what budget it counted against, what the agent's reputation is, what dispute window applies. MnemoPay records all of those alongside the tx hash. Auditors, finance teams, and regulators (EU AI Act Article 12) want the second set, not the first.

What about Google AP2 or Agent Commerce Kit?

Both are also rails / protocols that compose with MnemoPay the same way x402 does. See MnemoPay vs AP2 and MnemoPay vs Agent Commerce Kit.

npm install @mnemopay/sdk

Apache 2.0 · v1.11.1 · Free self-hosted forever