Custena is the European compliance layer for AI agent commerce. It covers all three sides of an agent-driven transaction under one integration: agents that pay (enterprises let their AI agents spend across x402, MPP, L402, and fiat from a single balance under unified governance), MCP servers and APIs that earn (operators monetize every tool call from any agent on the same four protocols, with settlement via Stripe Connect), and all of it governed (every transaction is cryptographically logged for EU AI Act Article 26 evidence, with enforcement beginning August 2, 2026).

What AI agent payment protocols does Custena support?

Custena supports all major AI agent payment protocols: x402 (Coinbase, HTTP-native, USDC on Base), L402 / LSAT (Lightning Labs, Lightning Network with macaroon bearer tokens), MPP (the Machine Payments Protocol co-authored by Stripe and Tempo, launched March 2026), and traditional fiat top-ups via credit card, SEPA, or USDC. No protocol bets needed. One integration covers all four.

How do I monetize my MCP server with Custena?

Register your MCP server URL in the Custena dashboard and set a price per tool call. Agents calling your server through Custena pay automatically across x402, MPP, L402, or fiat. No code changes to your MCP server are required; Custena acts as a reverse proxy. Alternatively, drop in the Custena SDK (npm install @custena/sdk or pip install custena) for deeper control: per-tool pricing, custom authorization logic, and richer audit events. In both cases Custena handles authentication, payment verification, protocol selection, and settlement to your bank account via Stripe Connect. There are 12,000+ MCP servers live today and almost none have a native monetization layer, making this the headline seller use case.

Can I monetize an API or HTTP endpoint with Custena?

Yes. Custena works for any HTTP endpoint: REST APIs, MCP servers, GraphQL, tool endpoints. Register your endpoint URL in the dashboard, set a per-call price, and route agent traffic through Custena's reverse proxy. No code changes are required. Custena handles protocol detection (x402, MPP, L402, or fiat Platform Balance), payment verification, and settlement via Stripe Connect.

How do I let my AI agents pay for API calls?

Create a Custena buyer account and top up a Platform Balance in fiat (card, SEPA, or bank transfer) or USDC. Issue per-agent API keys with optional daily or monthly spending caps, approval workflows on high-value calls, and instant kill switches. Your agents can then call any Custena-integrated MCP server or API endpoint. Custena automatically selects the correct payment protocol (x402, MPP, L402, or Platform Balance fiat), records every transaction with agent identity, endpoint, cost, timestamp, and protocol, and attaches an EU AI Act Article 26 compliance receipt. No crypto wallet required.

Does Custena help with EU AI Act Article 26 compliance?

Yes. Custena ships the three statutory obligations Article 26 places on deployers of high-risk AI systems: human oversight (Article 26(2)) via per-agent budgets, approval workflows, and instant kill switches; continuous monitoring (Article 26(5)) via real-time anomaly detection on agent spending; and log retention (Article 26(6)) via cryptographically logged transactions retained for six months or more and exportable on demand. Custena also issues machine-readable cryptographic receipts compatible with Mastercard Verifiable Intent (open-sourced March 2026) as a value-add beyond the statutory minimum. Article 26 enforcement begins August 2, 2026; non-compliance carries fines up to 3% of global annual turnover or €15M under Article 99(4). Deloitte's State of AI in the Enterprise 2026 reports that nearly three-quarters of enterprises plan to deploy agentic AI within two years, but only 21% have a mature governance model.

What are the penalties for EU AI Act Article 26 non-compliance?

Under Article 99(4) of the EU AI Act, Article 26 deployer violations are capped at 3% of the offender's total worldwide annual turnover in the preceding financial year, or €15 million, whichever is higher. The higher 7% / €35M tier under Article 99(3) applies only to Article 5 prohibited practices (social scoring, subliminal manipulation, etc.), not to Article 26 obligations. Enforcement for Article 26 begins August 2, 2026.

What does Custena cost?

Custena offers three tiers. Free trial: 60 days at 0% transaction fees, all protocols, full governance. Pay-as-you-go: 0.4% per transaction, no monthly minimum, unlimited endpoints. Enterprise governance: custom pricing from €500/month, includes the full Article 26 evidence pack, Slack approvals and human-in-the-loop workflows, and dedicated EU support. No credit card required to start.

EU AI Act Article 26 · ready day one

Your agents spend.
Your APIs earn.
All of it governed.

See every agent decision before it spends. Approve what matters. Hand a regulator the trace.

Get started Read the docs →

Install buyer agent with NPM (recommended)

Run install script Install on Claude Code Install on Codex

app.custena.com/buyer/compliance/a91f-2c3e-7b40-f18d-d119

Compliance / a91f-2c3e-7b40-f18d-d119

Trace a91f-2c3e-7b40-f18d-d119

HALTED2026-05-12T12:04:31.882Z

Awaiting approval - ops-agent $1,200.00 -> acme/payroll-api · POST /run over the $500.00 cap

BUDGET_CHECK_DAILY

scope: daily_spend_cap
priorSpend: $340.00
limit: $500.00
amount: $1,200.00
decision: HALT
reasoning: amount 1200 + prior 340 = 1540 > cap 500 -> human approval required
policyId: pol_7Q9ax · v3
at: 12:04:31.890 UTC

Protocols backed by

Lightning LabsTempo

These companies co-author or back the open protocols Custena implements - not Custena customers.

The governance gap

Your agents are spending.
Nobody can see or stop it.

The new agent payment protocols (x402, MPP, L402) handle the transaction. They carry no context, no controls, and no compliance evidence. The operational layer that enterprises actually need does not exist yet.

No visibility into what agents spend

Agents move money across x402, MPP, L402, and fiat. Raw transaction logs show amounts, not context. The CFO question - why did the agent buy this - has no answer anywhere in the stack.

No controls before the money leaves

Today's protocols only confirm a payment was valid. They carry no per-agent spending caps, no approval workflows for large calls, no kill switches. Nothing stops an agent from over-spending or buying from the wrong vendor.

EU AI Act Article 26 requires all of this

From August 2, 2026, Article 26 deployer obligations require human oversight, continuous monitoring, and log retention for autonomous AI systems - including the financial transactions they make. Fines reach 3% of global turnover.

Real-time policy

Spend caps, allow-lists, per-agent budgets - enforced before the call leaves the building.

ops-agent · daily spend cap$340 / $500 today

GET finance-api/forecast · $0.04ALLOWED

POST payroll-api/run · $1200OVER CAP

How it works

Your agent hits a paywall. Custena decides.

A policy gate sits between every agent and every outbound payment. Requests flow through in milliseconds when they stay within policy. Anything outside the rules pauses for human review - then continues.

Connect

Govern

Approve

Audit

Connect

Your agents call any API or MCP server, Custena-integrated or third-party. No per-protocol wallet setup; governance applies to every call.

Govern

Every request hits the policy gate: per-agent budgets, vendor allow-lists, category limits, and duplicate detection evaluated in real time.

Approve

Spends above a threshold ping the right human in Slack with full context. One click approves or denies - the agent waits for the decision.

Audit

Every transaction lands in the unified ledger: agent identity, endpoint, amount, reasoning, approver, and policy - ready for a regulator audit.

See the full walkthrough →

What Custena does

The building blocks of governed agent spending

Four capabilities, one platform. Each one maps to an Article 26 deployer obligation - and to a CFO or compliance team question that current protocol tooling cannot answer.

Real-time policy

Spend caps, allow-lists, per-agent budgets - enforced before the call leaves the building.

ops-agent · daily spend cap$340 / $500 today

GET finance-api/forecast · $0.04ALLOWED

POST payroll-api/run · $1200OVER CAP

Human approvals where it matters

Anything over the line gets a card - Slack, dashboard or API. Workflows wait; nothing leaks.

ops-agent wants to spend $1,200.00

payroll-api/run · over the $500 daily cap

Slack · dashboard · API

Every protocol, one integration

x402, MPP, L402 and fiat - agents pay outbound, your APIs earn inbound, on all of them.

x402

MPP

L402

fiat

one ledger

// same call, any rail

POST /proxy/acme/finance-api/forecast

→ paid via x402 (Base) · settled · span logged

Article 26 audit evidence

Every decision - allowed or halted - writes a span with the reasoning attached. Export it for a regulator.

research-agent · GET market-data/quote

within budget

ALLOWED

ops-agent · POST payroll-api/run

1200 > cap 500 -> human approval

HALT

approved by alice@acme.io

$1,200.00 · settled

SETTLED

EU AI Act Article 26 · Compliance

Compliant by default. From day one.

Article 26 enforcement begins August 2, 2026. Deployer obligations cover human oversight, continuous monitoring, and 6-month-plus log retention. Non-compliance carries fines up to 3% of global annual turnover under Article 99(4). Custena ships all three obligations on day one.

app.custena.com/buyer/compliance/b73d-5f6g-2h81-j40i-e556

Compliance / b73d-5f6g-2h81-j40i-e556

Trace b73d-5f6g-2h81-j40i-e556

SETTLED2026-05-12T12:04:31.882Z

APPROVAL_RESOLVED

resolvedBy: alice@acme.io
source: dashboard
resolution: APPROVED
latency: 38s

Human oversight

Art. 26(2)

Per-agent budgets, real-time approval workflows, and instant kill switches. Every spending decision your agents make can require sign-off before it executes.

Immutable audit trail

Art. 26(6)

Every transaction cryptographically logged with agent identity, endpoint, cost, timestamp, protocol, and the full reasoning chain. Retained 6 months or more. Exportable evidence for regulators, auditors, and disputes.

Continuous monitoring

Art. 26(5)

Real-time anomaly detection on agent spending. Drift alerts fire the moment behavior diverges from policy - before it becomes a compliance event.

Cryptographic receipts

Verifiable Intent

Machine-readable receipts prove each payment was authorized by a human principal - compatible with Mastercard Verifiable Intent (open-sourced March 2026).

Deadline: August 2, 2026. Deployers of high-risk AI systems must be able to show human oversight, continuous monitoring logs, and a 6-month-plus audit trail on demand. Custena ships the complete evidence package, not just a checkbox.

Two-sided platform

Built for both sides

Sellers monetize any MCP server or API in minutes. Buyers govern every dollar their agents spend - with the audit evidence to prove it.

For enterprise buyers

Govern what your agents pay for.

Deploy spending AI agents safely. Real-time policy enforcement, human approvals where it matters, and EU AI Act Article 26 audit evidence on every transaction.

See every dollar your agents spend
One unified ledger across x402, MPP, L402, and fiat.
Per-agent budgets and approval workflows
Set daily or monthly caps. Route high-value calls to a human.
EU AI Act Article 26 audit evidence
Cryptographically logged, 6-month retention, exportable on demand.
Instant kill switches
Revoke any agent's spending access in one click.

Govern agent spending Learn more →

For MCP and API sellers

Monetize in 2 minutes.

Register any URL, set your price, and start earning from AI agents. No code changes needed. Every protocol, one integration, settlement via Stripe Connect.

Register any URL - REST, MCP, GraphQL
No code changes required. Custena proxies and handles auth.
Accept x402, MPP, L402, and fiat
Every paying agent, on every protocol, through one integration.
Real-time revenue dashboard
Per-endpoint call volumes, revenue, and conversion in one view.
Stripe Connect settlement
Payouts to your bank account. EU-regulated fiat rails included.

Start earning Learn more →

Both sides on one ledger. See pricing

Pricing

Transaction fees to start. Enterprise governance plans when it matters.

Start free for 60 days. Pay a small percentage on what your agents spend or what your APIs earn. Enterprise governance plans for compliance teams with EU AI Act Article 26 evidence requirements.

Free trial

60 days 0% fees

All protocols
Full governance
No card required

Pay-as-you-go

0.4% per transaction

Sellers and buyers
No monthly minimum
Unlimited endpoints

Enterprise governance

Custom From €500/mo

Article 26 evidence pack
Slack approvals + HITL
Dedicated EU support

See full pricingNo credit card required to start

Get started today

Agents that pay.
APIs that earn.
All of it governed.

Start free for 60 days. No crypto wallet required. EU AI Act Article 26 compliance evidence on every transaction from day one.

Get started Contact sales