Build, Own, Scale.
Don't Rent.

The payment infrastructure map for merchants, SaaS & fintechs — now with 20+ MCP servers mapped across every layer

When you outgrow Stripe or Adyen, you face a maze of 200+ providers across 21 layers. STACKS maps who does what, what it costs, and what you actually own. V27: MPP goes live — machines pay machines. Tempo mainnet. Visa ships card-based MPP SDK. 25+ MCP servers. Stablecoins at $230B+. Fiat × Crypto × Agentic converging. Built from 8+ years operating inside the stack—not from vendor decks.

WHO BUILDS ON THE STACK
Merchant
E-com · Retail
Platform
Marketplace · SaaS
Fintech
Neobank · Wallet
Enterprise
B2B · Treasury
↓ Relies On
21 BUILDING BLOCKS
0 3 4 6 7 9 10 11 12 13
Acquiring · Vault · Route · Stablecoin · Agentic · Credit · Insurance
↓ Managed By
ADMIN BLOCKS
📊 Data
Analytics · BI
⚙️ Ops
Refunds · Disputes
🔄 Recon
Settlement · Ledger
🤖 V27 — MPP Goes Live: Machines Pay Machines

The payment stack is agent-readable AND agent-payable. 25+ companies ship MCP servers. MPP (Stripe/Tempo) adds machine-to-machine payments. Visa ships Card-Based MPP SDK + visa-cli. x402 V2 supports all ERC-20 tokens. Not just L11 — every layer from PSPs to fraud to card issuing to stablecoins. Look for the 🤖 MCP badge across the stack.

25+ MCP servers live
MPP Machine Payments Protocol LIVE (Stripe × Tempo)
Tempo mainnet + KlarnaUSD + Visa card spec
4 protocol lanes: ACP · MPP · x402 · UCP
$230B+ stablecoin supply · PYUSD 70 markets
Fiat × Crypto × Agentic convergence shipping

What Are You Trying To Solve?

Pick your issue. We'll highlight the building blocks that matter.

💰
Improve Margins
Move from ~2.9% to IC++ (~1.2%)
L4 → L5 → L6
📊
Own Your Data
Raw auth codes, proprietary models
L3 → L5 → L8
🔐
Own Your Tokens
No PSP lock-in, portable PANs
L4 → L6
🏦
Own Financial Products
Cards, wallets, accounts, stablecoins
L7 → L10.1
📒
Own Your Ledger
Real-time balances, multi-currency, crypto
L7 → L10
🛡️
Own Your Compliance
DORA, MiCA, PSD2/PSD3, NIS2
L3 → L7 → L10 → Backbone
📜
Get Licensed
Agent → EMI → PI → Bank
L3 → L5 → L7
🚀
New Rails Readiness
A2A, stablecoins, 24/7 settlement
L2 → L10.3
🤖
Prepare for Agentic
AI agents as buyers
L3.4 → L11.1 → L11.4
🔌
MCP Providers
20+ agent-ready APIs across the stack
L2 → L3 → L6 → L7 → L9 → L10
🔄
Show All Layers
Reset filter

The Complete Payment Stack

Click any block to explore providers. From bundled PSPs to agentic commerce.

MATURE Production-ready GROWING Rapid adoption 2025 Major updates AT TABLE In protocol working groups
Surface Layer — The Bundled Starting Points
Core Stack — Build Your Own
L2
Accept
Payment methods
AllShow all
Local APMsiDEAL, BLIK, etc.
BNPLBuy Now Pay Later
A2A / Open BankingBank transfers
CryptoStablecoin accept
Coverage
local methods
L3
Risk, Identity & Compliance
Fraud, Auth, KYC, Disputes
AllShow all
FraudML + guarantee
IdentityAuth + verification
KYC / KYBOnboarding
DisputesChargebacks
AMLSanctions
Own Risk
or outsource
Sardine vs Forter in Agentic: Sardine = AI agents automate YOUR fraud ops (internal). Forter TACP = authenticate EXTERNAL AI shopping agents. Different problems, both L3.
L3.4
Agentic Trust & Security NEW V26
Trust the agent as a transacting entity
AllShow all
Agent TrustAuthentication
Agent SecurityBot discrimination
Agent Trust
new primitive
L7
Ledger, Accounts & Cards
Own the financial products
AllShow all
LedgerSource of truth
BaaS / AccountsIBANs, wallets
Card IssuingDebit, credit
Own Products
wallets, cards, data
Embedded Finance — Credit & Insurance
L12
Credit & Funding
Lending, capital, treasury
AllShow all
Lending-as-a-ServiceEmbed credit
Credit DecisioningUnderwriting
Funding SourceCapital providers
Credit Stack
invisible but complex
L13
Embedded Insurance
Platform + Underwriter
AllShow all
PlatformDistribution/UX
UnderwriterRisk carrier
Coverage
always find both
Stablecoin Infrastructure — GENIUS Act + MiCA EXPLOSIVE 2025 FIAT × CRYPTO CONVERGING
L10.3
On/Off-Ramp & Card Issuing
Fiat↔crypto + spend stablecoins
AllShow all
On/Off-RampFiat ↔ Crypto
Crypto Card IssuingStablecoin spend
Accept CryptoMerchant payments
Spend USDC
at 150M+ merchants
Rain = Marqeta for stablecoins: $1.95B unicorn. 200+ partners. Visa Principal Member, omni-chain settlement. Powers Western Union, Nuvei, KAST. The crypto card issuing infrastructure layer.
Agentic Commerce Infrastructure — AI Payments 🟢 LIVE Q1 2026
How Agent Commerce Actually Works
User Request
👤 Human
"Buy me Nike Air Max size 10"
LLM = The Agent
🤖 Agent
ChatGPT, Claude, Gemini
L11.1 Standards
📡 Protocol
ACP, MPP, UCP, AP2
Receives API call
🏪 Merchant
Shopify, Direct API
Processes payment
💳 PSP
Stripe, Adyen
Key insight: Agent sends structured API request. Agent triggers, doesn't navigate. No "checkout page" — just protocol calls.
🔧 MCP is the foundation layer. Anthropic created MCP → Linux Foundation (AAIF). 97M+ monthly SDK downloads. 10K+ active servers. All commerce protocols (ACP, MPP, UCP, AP2, x402) build ON TOP of MCP. V27: 25+ payment companies ship MCP servers. MPP adds machine-to-machine autonomous payments. Protocol specialization, not protocol war.
L11.1
Protocols & Standards
Rules for AI-initiated transactions
AllShow all
Open ProtocolsStripe ACP, Google AP2
Network ProtocolsVisa, Mastercard
Crypto-Nativex402, KYA
Standards
interoperability
Protocol Specialization (not war): ACP = human-initiated agent commerce. MPP = machine-to-machine autonomous payments. x402 = HTTP-native crypto micropayments. UCP = Google's mandate model. Each finding its lane. Visa + Lightspark extending MPP to cards + Lightning. VGS as tokenization layer.
CROSS-STACK INDEX
🤖 MCP Server Catalog — 25+ Payment APIs, Agent-Ready
Not a layer. A map of every MCP server across the stack. Each entry lives on its home layer above — this is the index.
StripeL2
23 tools. PaymentIntents, refunds, subscriptions, search. LIVE
PayPalL2
Local + Remote. Payments, invoices, disputes, tracking. LIVE
AdyenL2
Agentic LLM integration. Google AP2 + UCP partner. PILOT
SquareL2
POS + invoicing. SMB agentic commerce. LIVE
ForterL3 · L3.4
MCP + TACP protocol. Real-time fraud for agents. LIVE
RiskifiedL3 · L3.4
AI Agent Approve (AWS Marketplace). Policy Builder. LIVE
Gr4vyL4
MCP per-tenant. AP2 partner. Checkout bridge. PILOT
VGSL6 · L3.4 · MPP
MPP Client Enabler (card TSP). 5B+ tokens. Network tokens + cryptograms for agents. LIVE
MarqetaL7
Read+write. Virtual cards, spend controls, disputes. LIVE
LithicL7
Read-only. Txns, accounts, balances. Safety-first. LIVE
PlaidL8
Account mgmt, real-time balances, link tokens. LIVE
ChargebeeL8 · MOR
AgentKit MCP. Billing + subscription automation. LIVE
Modern TreasuryL9 · PSP
PSP launched (Feb '26): fiat + stablecoin. ACH, wire, RTP, FedNow, USDC, USDG, USDP. LIVE
CircleL10.1
USDC ops, micropayments, wallets, x402 integration. LIVE
CoinbaseL10.2
Payments MCP + x402. Wallet, onramp, stablecoins. LIVE
FiptoL10.3
"Stablecoin Sandwich" — fiat in → settle → fiat out. ALPHA
VisaL11.2 · MPP
visa-cli + Card-Based MPP SDK. VIA Europe. 100+ partners. LIVE
MastercardL11.2
Dev Agent Toolkit. Service discovery, API docs. LIVE
PaddleMOR
Subscriptions, pricing, invoices, revenue metrics. LIVE
GoCardless NEWL9 · A2A
Bank payments via natural language. A2A + open banking. Feb '26. LIVE
Fingerprint NEWL3
Device intelligence for AI fraud prevention. Mar '26. Industry-first. LIVE
Pagos EXPANDEDDATA
Harmonized payments data via chat. Open-source. Feb '26 expansion. LIVE
Payabli NEWL2 · EMBED
Forbes Fintech 50. Embedded payments for vertical SaaS. Agentic workflows. LIVE
BrexL7
Community-built. Card expenses, budget mgmt. Read-only.
XeroAdj.
Community-built. Accounting via MCP.
Alpic FRINFRA
First MCP-native cloud. Deploy in minutes. Top 10 SDK contributor.
StainlessINFRA
Generate MCP servers from your API. Powers OpenAI SDK.
SpeakeasyINFRA
OpenAPI → MCP server. Clients: Formance, Mistral.
AAIFGOV
Linux Foundation. MCP governance + goose (Block) + AGENTS.md.
This is not a layer. Every 🤖 badge on the stack above maps to an entry here. Sorted by home layer (L2 → L11.2 → MOR). V27 adds GoCardless (A2A), Fingerprint (fraud), Pagos (data), Payabli (embedded). MPP creates a new cross-cutting axis: machine payments across cards (Visa), crypto (Tempo), and Lightning (Lightspark).
⚖️ Regulation Watch — Shapes Every Layer
🇺🇸 GENIUS Act
Stablecoin framework: reserves, audits, licensing
Signed Jul '25 → Regs due Jul '26
↳ L10.1, L10.2, L10.3
🇪🇺 MiCA
Crypto-asset licensing, stablecoin caps, CASP rules
Full enforcement Jul 1, 2026
↳ L10.1, L10.2, L10.3, L10.4
🇪🇺 PSD3 / PSR
Open banking 2.0, fraud liability, API standards
Agreement Nov '25 → Compliance '27-28
↳ L2, L7, L8
🇺🇸 Nacha ACH
Same-day ACH limit raised to $10M. RTP expansion.
✓ Active Mar '26
↳ L9, L7
🇪🇺 CARF / DAC8
Crypto tax reporting, cross-border info exchange
✓ Active Jan 1, 2026
↳ L10.1, L10.2, L3

What Runs Your Stack

When you unbundle from Stripe/Adyen, you lose their dashboard. You need to rebuild three things.

📊
DATA
What really happened?
Decline codes Settlement IC breakdown Audit trails
Pagos — Payment intelligence
dbt — Transform payment data
Metabase — Open-source BI
Compliance (DORA, MiCA, PSD2)
Vanta — SOC2, DORA evidence
Drata — Continuous monitoring
⚙️
ADMIN
Let me manage it
Tokens Refunds Disputes Sub-merchants
Retool — Custom internal tools
Forest Admin — Back-office on data
Appsmith — Open-source tools
🔄
PROCESS
Automate it
Reconciliation Workflows Retries Dunning
Modern Treasury — Reconciliation
n8n — Workflow automation
Temporal — Durable execution
Compliance Workflow Pattern
Trigger Analyze Human Review Execute
Architecture Principle: Dual-Database
🏦
Banking Ledger
Regulatory source of truth. Immutable. Auditable.
Held by license holder
Sync
💾
App Database
Feature layer you control. Product logic, user data.
Owned by fintech
💡
Why this matters: Back-office tools (Forest Admin, Retool) operate on your App Database — not the Banking Ledger. You can't "fix" regulated data directly. This is why reconciliation matters, why Formance exists, and why BaaS isn't just "renting accounts."
The pattern: As you go deeper in the stack, operational complexity increases. Admin blocks become essential — not optional.

Find Your Profile

Your business model determines which building blocks matter most.

🏪
Marketplace / B2B SaaS Platform
Multi-seller splits, escrow, seller payouts
When should I own my ledger?
Full-Stack PSP
Stripe Connect
<€10M GMV
Regulated Platform
Lemonway, Mangopay
Standard splits
BaaS + Own Logic
Formance + Swan
€50M+ GMV
Full Build
Formance + EMI
Split IS product
Product → Supplier Linkage
Seller Payouts Formance Swan Wise
Critical Layers
L3 KYCL7 LedgerL9 SplitsL9 Payouts
PayFac / Embedded Payments
Embed payments, own merchant relationship
How deep do I go?
PSP Wrapper
Stripe Connect
Fast, their compliance
Orchestrate + Vault
ProcessOut + VGS
Multi-PSP, own tokens
Sponsor Model
BPCE + Duna
Own compliance
Full PayFac
Own license
€500M+ volume
Product → Supplier Linkage
Sub-Merchant Onboard Persona KYC Sponsor Bank Visa/MC
Critical Layers
L3 KYCL5 SponsorL6 VaultL7 Ledger
🏬
Omnichannel Retail
Unify online + POS, one customer view
How do I unify online and in-store?
Single PSP
Adyen Unified
Simplicity
POS Abstraction
Nepting + PSP
Multi-acquirer POS
Unified Vault
VGS + Nepting
Single token
Direct Acquiring
Silverflow + VGS
€100M+, IC++
Critical Layers
L1 POSL4 OrchestrationL6 VaultL5 Direct
🏦
Fintech / Neobank
Issue cards, generate accounts
BaaS wrapper or build the bank?
Full BaaS
Swan, Unit
Fast, their license
BaaS + Ledger
Formance + Swan
Custom logic
Core Banking
Mambu + EMI
Full products
Full Build
Mambu + License
You ARE the bank
Product → Supplier Linkage
Card Issuing Marqeta Visa Bank Sponsor
Critical Layers
L3 KYCL7 LedgerL7 BaaSL7 Cards
🌍
Global Payouts
Pay creators, suppliers, 100+ countries
Traditional rails or crypto?
Traditional FX
Wise, Airwallex
Established corridors
Mass Payout
Payoneer, Tipalti
High volume
Emerging
Thunes, Nium
Africa, LatAm
Stablecoin
Bridge, Lightspark
24/7, zero FX
Critical Layers
L3 IdentityL9 FXL10.3 SettlementL11.2 Agent Wallets
🔗
Crypto Player
Exchanges, wallets, DeFi going compliant
How do I bridge to fiat?
Crypto-Native
DFNS, Fireblocks
Custody only
Fiat Ramp
MoonPay, Sardine
User fiat entry
BaaS
Swan + Chainalysis
Fiat accounts
Full Banking
Mambu + Cards
Crypto bank
Critical Layers
L2 Fiat rampL3 SardineL7 BaaSL10.2 Custody

Case Studies Coming Soon

Deep dives into how leading companies actually built their payment infrastructure.

Klarna
BNPL → IPO → KlarnaUSD on Tempo
Shopify
PayFac at $200B+ GMV
Toast
Vertical SaaS → Full Stack
Revolut
Neobank Multi-License

Nicolas & Friends

Operators, not consultants. We've built the stacks, not just advised on them.

Curator
Nicolas Devillard
8 years scaling a European PSP from early stage to €100M+ revenue. Grew the team from 15 to 400+. Saw every layer decision firsthand—what worked, what didn't, what we'd do differently.
CRO @ PayPlug (BPCE) €100M+ Revenue Now in NYC
Connect →
Contributors
Friends of the Stack
Payment architects, fintech founders, merchant CTOs, and infrastructure nerds who've lived the build-vs-buy decisions. This isn't theory—it's pattern recognition from the trenches.
Merchants PSP Veterans Fintech Founders Advisory Firms
Philosophy
Challenge the Status Quo
Most payment content is vendor marketing. We're here to show what actually works—from real infrastructure, real trade-offs, real failures. No sponsored content. No affiliate links.
No BS Operator POV Open Source Intel

Want to go deeper?

Stack reviews, infrastructure audits, build-vs-buy decisions. If you're making a call on your payment infrastructure, let's talk.