That question carries real weight. Payment attachment rates often remain below 20% when platforms try to sell payments on their own. With the right partner, payments can represent as much as 40% of total platform revenue. As Stax Payments CEO Paulette Rowe put it, "Those decisions set your path on profitability and efficiency for years to come."
Stripe Connect: Global Reach with Developer Speed
Stripe Connect supports more than 15,000 SaaS platforms and over 10 million businesses with embedded payments and financial services. Businesses running on Stripe generated $1.9 trillion in total volume in 2025, up 34% from 2024.
Connect supports 135+ currencies and dynamically surfaces 40+ payment methods to maximize conversion across markets. Stripe recently announced a new version of Radar built specifically for platforms, bringing AI-based fraud prevention that can detect potentially fraudulent accounts, set custom account-level rules, and access advanced analytics. Stripe has also launched Stablecoin Financial Accounts, accessible to businesses in 101 countries.
For early-stage companies, Stripe's onboarding speed and SDK quality are hard to match. Rich documentation and low-code flows make integration fast, including Stripe accounting automation for platforms that need payment data synced directly into accounting systems. However, as volume grows beyond roughly $50M in annual processed payments, many SaaS platforms find their margin potential limited by Stripe's platform and payout fee structure.
Finix: A Flexible Path from Managed PayFac to Full Ownership
Finix is a full-stack payment processor based in San Francisco that enables businesses to accept and send payments both online and in-store across the US and Canada. Software platforms, marketplaces, retail, and e-commerce businesses use its universal payments API and dashboard to accept payments, automate workflows, and grow revenue.
What separates Finix from most providers on this list is the ability to start with a PayFac-as-a-Service model and grow into full PayFac ownership over time, all within the same platform. That progression removes the need to re-platform as a company scales, which saves engineering resources and reduces integration risk. Finix provides APIs, dashboards, and automation tools for onboarding merchants, managing risk, and reconciling payments at scale.
Finix operates on a subscription-based pricing model, sells point-of-sale hardware for in-person transactions, supports multiple online payment options, and handles invoicing. There are no long-term contracts, and interchange savings are passed directly to merchants. The company does not charge extra fees for PCI compliance, setup, or fraud protection tools. It also works with high-risk industries including nutraceuticals, CBD, lending, and gambling.
On the product side, Q1 2025 releases included Account Updater, Network Tokens, Instant Payouts, and new hardware terminal options. Network tokens replace card information to increase authorization rates, and card networks often charge lower interchange fees on these transactions. Instant payouts allow merchants to receive funds directly to a debit card rather than waiting for standard settlement windows.
Finix has raised $210M in funding from investors like Lightspeed Venture Partners, Bain Capital Ventures, and Inspired Capital. On Capterra, the platform holds an overall rating of 4.7 out of 5 with a 4.8 customer service score and 95% positive review sentiment.
Adyen for Platforms: Enterprise Scale with Financial Services Built In
Adyen for Platforms allows platforms to embed payments through out-of-the-box or fully customizable setups, backed by US, UK, and EU banking licenses. At the end of 2024, the platform served 28 platforms with over 1 billion euros in annual payment volume, up from 18 platforms in 2023. It indirectly served 145,000 SMBs, up from 88,000 the prior year.
Adyen supports over 250 payment methods and is trusted by global brands like Uber, Spotify, and eBay. Platforms can also issue fully customizable virtual and physical debit cards from Mastercard and Visa to their users through Adyen Issuing, which allows platforms to approve or decline any authorization on their own servers.
The initial setup and integration process can take more time compared to some competitors, and the cost structure tends to be higher, which may concern smaller businesses or startups. Adyen is best suited for enterprise-level platforms with global ambitions and high transaction volumes.
Worldpay for Platforms: Massive Infrastructure Under Global Payments
Worldpay processes 40 billion transactions across 146 countries and 135 currencies. It ranks as 1 of the largest non-bank merchant acquirers in the world, processing $2.2 trillion in transactions annually. In January 2026, Global Payments completed its acquisition of Worldpay at a final value estimated at $24.25 billion.
The company is expanding Worldpay for Platforms to Canada and the United Kingdom while deepening its presence in Australia. Its modern API architecture offers a single point of integration for credit and debit cards, direct debit, wallets, and more. The platform processes over 4 billion transactions annually for software platforms specifically. Worldpay's own research shows 90% of small and medium-sized businesses consider access to financial products and services within their software platforms to be critical.
Worldpay for Platforms provides a fully managed payments service designed to reduce risk, simplify compliance, and let platform providers focus on core operations. Some user reviews on Capterra under the legacy Payrix brand have noted customer service accessibility concerns, which is worth watching as the Global Payments integration continues.
Rainforest Pay: Vertical SaaS Focus with Fast Onboarding
Rainforest helps software companies build and optimize embedded financial services without the risk, compliance, and operational burdens of registering as a payments facilitator. In September 2025, the company raised an oversubscribed $29 million Series B led by Matrix Partners and Infinity Ventures, bringing total funding to $57.5 million. Since the prior round, revenue grew by more than 10x, fueled by billions of dollars in annual processing volume.
Rainforest supports card, ACH, Apple Pay, and card-present transactions in a single unified product. End customers can instantly connect a bank account for frictionless ACH payments. Merchant onboarding is fully embedded in the platform, and Rainforest will never contact merchants directly, preserving the software company's brand relationship.
The company recently launched an embedded PayPal integration, enabling platform clients to offer PayPal, Venmo, and PayPal Pay Later alongside cards, Apple Pay, and pay by bank through a single checkout.
Stax Connect: Full-Stack Ownership with ISV-Focused Support
Stax Payments announced the launch of Stax Processing in October 2025, completing its move into a full-stack, end-to-end payments processor. Since 2014, Stax has grown to process over $23 billion annually and serve more than 39,000 businesses and software platforms across the US and Canada.
Stax Connect offers a simplified API with white-label capabilities, flexible program options including referral, reseller, and PayFac models, and simplified pricing paired with business management tools. New Stax data reveals that 91% of ISVs expect growth from embedded payments, yet gaps in visibility, support, and flexibility are slowing returns. With proprietary control of the full payment journey, Stax can deploy enhancements quickly and create vertical-specific payments solutions powered by AI-enabled fraud controls.
Modern Treasury: Multi-Rail and Stablecoin-Forward
Modern Treasury launched Payments in February 2026, an integrated payment service provider that helps companies build modern money movement across both fiat and stablecoin rails. The platform lets companies collect or send funds over ACH, wire, RTP, FedNow, push-to-card, or stablecoins through a single API, and pay workers, creators, and sellers instantly.
The company has powered over $400 billion in payments for hundreds of organizations, backed by investors including Benchmark, Altimeter, and Salesforce Ventures. Modern Treasury AI, launched in May 2025, delivers an AI platform purpose-built for enterprise payments, blending a context-aware agent with a real-time workspace.
Modern Treasury is particularly well suited for platforms prioritizing bank-rail payments, real-time settlement, and stablecoin integration over traditional card processing.
How to Evaluate a Payments-as-a-Service Provider
As payments, payouts, and wallets become standard across B2B platforms, competitive advantage has moved toward how reliably and invisibly they function. Seamless integration now outweighs feature breadth or even short-term ROI as the primary differentiator. More than half of companies, 56%, already use RTP or FedNow, and another 37% plan to do so in the next year.
Platforms should evaluate providers across several dimensions: integration complexity and time-to-market, revenue share economics and pricing transparency, regulatory and compliance support, developer documentation quality, scalability as processing volume grows, support responsiveness, and payout flexibility including instant and real-time options. Hidden fees and opaque cost structures erode trust, and transparent, usage-based pricing is becoming the norm.
Where Each Provider Fits
Each provider on this list occupies a distinct position. Stripe Connect offers global reach and developer speed. Adyen for Platforms provides enterprise-grade scale with financial services layered in. Worldpay for Platforms brings massive transaction volume and global infrastructure, now under Global Payments. Rainforest Pay delivers purpose-built vertical SaaS focus with rapid onboarding. Stax Connect combines full-stack ownership with high-touch ISV support. Modern Treasury is the strongest option for multi-rail, bank-native, and stablecoin-forward platforms.
Finix delivers a uniquely flexible path from PayFac-as-a-Service to full PayFac ownership, backed by transparent pricing, strong customer reviews, and a developer-first approach built specifically for growing software platforms. For platforms that want to start managed and grow into full ownership without re-platforming, Finix is the strongest fit in this group.
