Best Payment Processors in the US (2026): Fees, Pros & Cons

While credit cards still dominate, the Instant Payment revolution has arrived. Merchants are balancing traditional card processing with account-to-account transfers and a growing demand for Merchant of Record (MoR) models. Here are the best platforms for 2026.

Alok Vats

Product

12 min read

Jun 18, 2026

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The US payment market in 2026 is going through one of its biggest changes in decades.

Credit cards still dominate online and in-person commerce, but businesses are increasingly adopting account-to-account payments, ACH, instant bank transfers, and faster settlement through networks such as FedNow and RTP.

At the same time, merchants must manage sales tax rules across thousands of state and local jurisdictions. This has increased interest in Merchant of Record platforms that handle payments, tax collection, invoices, refunds, and compliance on behalf of the business.

AI and SaaS companies face an additional challenge. AI agents, APIs, and automated workflows can generate costs every time they run. These products need billing systems that can manage subscriptions, credits, wallets, tokens, API calls, agent actions, and real-time customer access.

This guide compares the best payment processors and Merchant of Record platforms in the US based on their fees, strengths, limitations, and ideal use cases.

The fees below are indicative. Actual pricing may vary based on payment method, business type, transaction volume, risk profile, and negotiated agreement.

1. Stripe #

Stripe remains one of the leading payment platforms for US SaaS companies, technology startups, marketplaces, and online businesses.

Its developer tools support card payments, ACH, subscriptions, invoicing, marketplaces, tax calculation, fraud prevention, and international payments.

Best for: SaaS companies, technology startups, marketplaces, and businesses that want to build and control their own payment infrastructure.

Indicative fees:

• Domestic cards: 2.9% + $0.30
• International cards: 2.9% + $0.30 + 1.5% international card fee (Effective rate: 4.4% + $0.30)
• Currency conversion: Additional 1% when applicable
• ACH Direct Debit: 0.8%, capped at $5.00 per transaction
• Instant payouts: Available for an additional fee

Pros:

• Strong developer experience: Detailed APIs, SDKs, documentation, and testing tools.
• Subscription billing: Supports recurring payments, invoices, trials, upgrades, and payment retries.
• ACH and bank payments: Offers bank-based payment options alongside cards.
• Stripe Tax: Helps calculate sales tax, VAT, and GST based on the customer’s location.
• Marketplace infrastructure: Stripe Connect supports platforms that collect and distribute payments.
• Fraud protection: Stripe Radar helps identify and block suspicious transactions.

Cons:

• Stripe Tax helps calculate and collect tax, but the business remains responsible for registrations, filings, and remittance.
• Automated risk reviews can sometimes result in account restrictions or delayed payouts.
• Complex usage billing, credits, and customer access may require additional development.
• Smaller businesses may find it difficult to access dedicated support.

2. Kelviq #

Kelviq is becoming the go-to billing stack for AI SaaS in the US. It gives you real usage-based billing and takes on the tax pain for you, so you do not have to think about filings or nexus rules. It is especially popular with AI and compute-heavy products that need precise costs and clean compliance.

Kelviq is designed for AI products and agents, where customers may be charged based on tokens, API calls, agent runs, workflows, credits, seats, or other forms of usage.

Best for: AI startups, AI agents, SaaS companies, APIs, developer tools, and digital product sellers serving global customers.

Indicative fees: Flat 3.9% + $0.40 per transaction. There are no monthly platform fees or separate ingestion fees for reporting API calls and product usage.

Pros:

• US sales tax and global tax handling: Kelviq calculates, collects, and remits sales tax, VAT, and GST where required.
• Built for AI and agents: Supports tokens, API calls, agent runs, workflows, credits, top-ups, seats, subscriptions, and pay-as-you-go pricing.
• Usage-based billing: Charge customers based on actual product usage, fixed plans, prepaid credits, or a combination of pricing models.
• Credits and wallets: Create prepaid balances, usage credits, top-ups, and rollover rules.
• Real-time access control: Check a customer’s subscription, balance, credits, entitlements, or usage limit before an AI agent or workflow runs.
• Complete revenue system: Payments, subscriptions, usage metering, tax, invoices, refunds, and customer access are managed together.
• Entitlements: Control which features, usage limits, and products each customer can access.
• Reduced webhook work: Kelviq’s SDKs help teams manage usage reporting, feature access, and customer entitlements directly inside the product.
• Global selling: US businesses can sell internationally without separately managing tax registrations in every market.

Cons:

• Not built for e-commerce or physical products.

3. Square #

Square is one of the strongest payment platforms for US businesses that sell both in person and online.

Its ecosystem combines payment terminals, point-of-sale software, online stores, inventory, appointments, payroll, and business banking tools.

Best for: Retailers, restaurants, service businesses, and small companies with both physical and online sales.

Indicative fees:

• In-person payments: 2.6% + $0.15 per transaction
• Online payments: 2.9% + $0.30 per transaction
• International cards: Additional fees may apply
• Instant transfers: Available for an additional fee (currently around 1.95%)
• Standard settlement: Typically the next business day

Pros:

• Point-of-sale hardware: Offers card readers, registers, terminals, and mobile payment tools.
• Online and offline sales: Connects physical inventory and online orders.
• No mandatory monthly fee: Basic payment processing is available without a monthly subscription.
• Business tools: Includes appointments, payroll, invoicing, inventory, and restaurant software.
• Easy setup: Suitable for small businesses without dedicated technical teams.

Cons:

• Not designed for advanced SaaS subscriptions or usage-based billing.
• Flat transaction rates can become expensive for high-volume merchants.
• Less flexible than Stripe for custom payment infrastructure.

4. Adyen #

Adyen is an enterprise payment platform used by large global brands, marketplaces, and retailers.

It operates as both a payment processor and acquirer in many markets, helping businesses manage online and in-person payments through one platform.

Best for: Large enterprises, global retailers, marketplaces, and high-volume businesses.

Indicative fees: Adyen typically charges a fixed processing fee plus the applicable card or payment-method fee. Card payments commonly use an Interchange++ pricing model.

Pros:

• Direct acquiring: Reduces the number of parties involved in processing some transactions.
• Unified commerce: Connects online, mobile, and physical store payments.
• Global payment data: Businesses can view transaction performance across markets from one system.
• Fraud protection: RevenueProtect helps identify and manage suspicious payments.
• Enterprise infrastructure: Designed to process large transaction volumes.

Cons:

• Not suitable for very small businesses or early-stage startups.
• Integration and onboarding can require significant technical resources.
• Pricing can be more difficult to estimate than flat-rate providers.

5. Authorize.net #

Authorize.net is one of the longest-running payment gateways in the US.

It is commonly used by established businesses that want a traditional gateway and the flexibility to work with their own merchant account provider.

Best for: Established retailers, professional services, traditional businesses, and companies that already have a merchant account.

Indicative fees:

• All-in-one plan: Around $25 per month plus 2.9% + $0.30
• Gateway-only plan: Around $25 per month plus transaction and batch fees

Pros:

• Established infrastructure: Has operated in the US payments market for many years.
• Gateway-only option: Businesses can connect an existing merchant account.
• Phone support: Provides access to human customer support.
• Fraud tools: Offers configurable fraud detection settings.
• Recurring billing: Supports standard subscriptions and recurring payments.

Cons:

• Charges a monthly gateway fee.
• The dashboard and developer experience may feel dated.
• Does not provide the full financial ecosystem offered by Stripe or Square.
• Not designed for modern AI or usage-based billing.

6. Helcim #

Helcim uses an Interchange Plus pricing model instead of charging one flat rate for every card transaction.

This can make it attractive to growing businesses that process enough volume to benefit from lower card network costs.

Best for: Established small and medium-sized businesses processing significant monthly payment volume.

Indicative fees:

• In-person: Interchange plus a Helcim markup
• Online: Interchange plus a slightly higher markup
• Rates decrease automatically as transaction volume grows
• No standard monthly processing fee

Pros:

• Transparent pricing: Separates card network costs from Helcim’s markup.
• Automatic volume discounts: Processing margins decrease as sales increase.
• No long-term contract: Standard accounts do not require lengthy commitments.
• No cancellation fee: Businesses can leave without a termination charge.
• Omnichannel support: Offers online payments, invoicing, and point-of-sale tools.

Cons:

• Flat-rate providers may be cheaper for small transactions or low-volume businesses.
• Underwriting and approval may take longer than instant-signup platforms.
• Not designed for complex software billing and entitlements.

7. PayPal and Braintree #

PayPal remains an important checkout option because many US customers already have PayPal or Venmo accounts.

Braintree, which is owned by PayPal, provides developer tools for accepting PayPal, Venmo, cards, and digital wallets through one integration.

Best for: E-commerce businesses that want to offer familiar consumer payment options.

Indicative fees:

• Standard PayPal checkout: Around 2.99% plus a fixed fee
• Venmo business payments: Around 3.49% plus a fixed fee
• Braintree card pricing: Varies based on account and payment type
• Instant transfers may have an additional fee

Pros:

• Customer familiarity: PayPal is widely recognized by US and international customers.
• Venmo support: Useful for businesses targeting younger US consumers.
• Digital wallets: Braintree can support cards, PayPal, Venmo, and other wallets.
• Seller protection: Eligible physical-goods transactions may receive additional protection.
• Global reach: PayPal is accepted across many international markets.

Cons:

• Transaction fees can be higher than some competitors.
• Merchants sometimes report difficulties with disputes and account restrictions.
• Not designed as a complete SaaS billing or tax platform.
• PayPal balances and bank settlements may follow different timelines.

8. Lemon Squeezy #

Lemon Squeezy is a Merchant of Record for software, SaaS, and digital products.

It becomes the legal seller for each transaction and handles customer payments, US sales tax, international VAT and GST, invoices, refunds, and related compliance responsibilities.

Best for: Digital creators, independent developers, and SaaS companies selling standard software products globally.

Indicative fees: Around 5% + $0.50 per transaction. Additional fees may apply for some payment types, subscriptions, or international transactions.

Pros:

• Sales tax handling: Manages tax collection and remittance across supported jurisdictions.
• Global selling: Helps digital businesses accept international payments.
• Merchant of Record: Takes legal responsibility for the customer transaction.
• Subscriptions: Supports standard recurring software plans.
• Digital delivery: Suitable for software licenses and downloadable products.

Cons:

• Fees are higher than standard payment gateways.
• Businesses have less control than when using their own merchant account.
• Not suitable for advanced AI billing, wallets, real-time credits, and complex entitlements.

9. Airwallex #

Airwallex is designed for businesses that manage international payments, currencies, suppliers, and remote teams.

It combines online payment acceptance, multi-currency accounts, foreign exchange, international payouts, and corporate cards.

Best for: International e-commerce businesses, agencies, importers, exporters, and global teams.

Indicative fees:

• Domestic cards: Around 2.8% + $0.30
• International cards: Higher fees may apply
• Foreign exchange markup: Often lower than traditional banks
• International transfer pricing varies by destination and currency

Pros:

• Multi-currency accounts: Hold and receive funds in several currencies.
• Foreign exchange: Offers competitive currency conversion rates.
• International payouts: Pay suppliers, contractors, and employees across different markets.
• Virtual cards: Issue corporate cards for subscriptions, advertising, and team expenses.
• Global operations: Useful for companies that frequently move money across borders.

Cons:

• Not as strong as Square for in-person US retail.
• The financial and treasury tools may be unnecessary for simple businesses.
• Does not replace a full SaaS billing, entitlement, or Merchant of Record system.

US Payment Processor Comparison #

Frequently Asked Questions #

Which US Payment Processor Should You Choose?

The best payment processor depends on what you sell, how customers pay, where they are located, and how much payment infrastructure you want to manage.

• For a SaaS company or technology startup that wants to build its own payment infrastructure: Stripe offers flexible APIs, subscriptions, ACH payments, tax calculation, and marketplace tools.
• For an AI agent, AI API, SaaS product, or usage-based software company: Consider Kelviq. It combines payments, US sales tax, international tax compliance, subscriptions, credits, wallets, usage billing, and customer access in one platform.
• For a retailer, restaurant, or service business: Square provides payment hardware, point-of-sale software, inventory, appointments, and online commerce tools.
• For a large global retailer or enterprise: Adyen offers direct acquiring, unified commerce, and payment infrastructure for high transaction volumes.
• For an established business that wants to use its own merchant account: Authorize.net provides a reliable gateway-only option.
• For a growing business that wants transparent Interchange Plus pricing: Helcim may reduce costs as monthly payment volume increases.
• For an e-commerce company that wants PayPal and Venmo: PayPal and Braintree provide familiar payment methods that can improve checkout conversion.
• For a creator or SaaS founder selling a simple digital product globally: Lemon Squeezy provides a Merchant of Record model with payments and tax compliance.
• For a company managing international currencies, suppliers, and payouts: Airwallex can help reduce foreign exchange costs and simplify global money movement.

What is the impact of Instant Bank Payments like FedNow and RTP?

FedNow and RTP are making faster account-to-account payments more accessible across the US. However, support depends on the merchant’s bank, payment provider, transaction type, and customer bank. Businesses should not assume that every payment gateway supports direct FedNow or RTP checkout.

ACH remains the most widely supported bank payment option for online businesses. It is particularly useful for subscriptions, invoices, and high-value B2B payments where card fees can become expensive. When comparing providers, always ask about ACH acceptance, instant payment support, payment confirmation speed, and transaction limits.

How does Payment Processing differ for AI Agents?

Traditional billing systems were designed around fixed monthly subscriptions and human-initiated purchases. AI products work differently. Agents can run workflows, call APIs, consume tokens, use external tools, and create compute costs without a person manually approving each action.

Before an agent runs, the product may need to check if the customer has access, active subscriptions, available credits, or if they have hit their usage limits. After the action runs, the product must record usage, update the balance, calculate the charge, and surface this in the customer portal. For AI companies, billing is real-time infrastructure, not just end-of-month collection.

The Bottom Line: There is no single best payment processor for every US business. For AI, SaaS, API, and digital product companies, payment processing is only one part of the problem. These businesses also need to manage sales tax, subscriptions, usage-based pricing, credits, wallets, invoices, refunds, and customer access.

Want to streamline your SaaS billing and tax compliance? Try @kelviqcom to manage everything in one platform.