High-touch embedded payments for vertical software. Stax is the facilitator in the managed models. Sales-led. No public platform buy rate. Traditional PayFac is listed as a model, not a documented same-stack license path.
What it is
Stax Connect is Stax’s embedded payments product for software companies and independent software vendors (ISVs). The official domain is staxpayments.com. fattmerchant.com redirects there. The company launched in July 2014 as Fattmerchant, rebranded to Stax in 2021, and says Stax Connect was born in 2020.
This is not Stax Pay. Stax Pay is the merchant-facing processor (subscription pricing, invoicing, terminals). Stax Connect is the partner and platform product: a single API, white-label UX, and a partner portal (Command Center) for enrolling and managing sub-merchants. Docs describe a PayFac-like experience through that API. PCI docs also state that Stax is a payment facilitator.
Current product pages sell flexible partnership models: referral, reseller, and PayFac (they also write “managed and traditional PayFac”). The PayFac-as-a-service page defines PFaaS as partnering with a payment facilitator so the platform can offer payments without becoming a full-fledged PayFac. In that model the PayFac handles onboarding, underwriting, and risk management. The embedded-payments page treats traditional PayFac as the high-control option: processing fees, pricing, underwriting, enrollment, and risk. It also says that option takes the most investment in development, operations, and sales.
In October 2025 Stax announced Stax Processing, an in-house end-to-end processing stack with direct connections to Visa, Mastercard, Discover, and American Express OptBlue. The current Connect product page lists those card-brand connections as part of the stack.
Stax also sells Stax Bill (recurring billing), CardX by Stax (compliant surcharging), and Payment Depot by Stax (interchange-plus for merchants). Those are Stax products. They are not this page.
Who it’s for
Four shapes, from Stax’s own product pages. Reseller is named next to the others and is not defined in the same depth.
- Referral, including Stax Connect Plus. Stax (or a Stax team) sells, onboards, and supports payments. The ClientTether case study calls Connect Plus Stax’s referral model that handles payments from beginning to end. A typical Connect Plus flow, from that product page: Stax receives a lead, contacts the merchant, submits the application to underwriting, works pended items, and supports early adoption.
- Reseller. Named on the Connect, ISV, and SaaS-platform pages as a program option. Public pages do not spell out how reseller economics or underwriting differ from referral or managed PayFac.
- Managed PayFac / PayFac-as-a-service. The platform embeds payments, keeps some control of the user experience, and monetizes through contract terms (the PFaaS page says revenue share is split that way). Stax stays the facilitator for onboarding, underwriting, and risk.
- Traditional PayFac. The platform is sold the goal of controlling fees, pricing, underwriting, enrollment, and risk. Public pages name this model. They do not document sponsorship, registration, or a same-stack timeline for becoming the licensed PayFac.
Connect’s product page says it is built for vertical SaaS teams in field services, professional services, healthcare, education, and non-profit. The SaaS-platform page adds legal and accounting. The about page states more than 30,000 merchant customers and 150+ integrated software partners. An October 2025 processing announcement says Stax serves businesses and software platforms across the U.S. and Canada. Funding docs describe U.S. banking days and U.S. bank holidays.
It is a fit for a vertical software company that wants a white-labeled payments program, a high-touch partner success motion, and Stax holding facilitator work, and that is willing to start through sales rather than a public signup.
Standout details
- Partner start is sales-led. Product pages push Contact sales and Request a demo. Docs’ average implementation timeline is 45 days. A Partner Sandbox can test merchant creation, enrollment, SSO, webhooks, and enrollment states. Docs require a valid partner account and signed documents before that sandbox. This is not a public self-serve live start.
- Merchant enrollment has four documented paths: a Stax-hosted white-labeled landing page (docs: 0 to 1 hour of development, one pricing option per page), white-glove (partner staff pre-fill six fields in Connect and send the merchant a link), hybrid API (start in the software, SSO into Stax’s white-labeled signup), and custom API (enrollment stays inside the product; docs estimate about 2.5 weeks for a dedicated developer, plus 50+ registration fields, document upload, and e-signature). Custom API partners must display the sub-merchant agreement and any required pricing information.
- Stax underwrites sub-merchants. In-house risk is sold as AML/KYC checks, daily monitoring, and controls. Docs add CIP checks and a first-review SLA of about 36 to 48 hours after signature. Statuses include Awaiting Signature, Awaiting Review, Application Pended, Application Rejected, and Application Approved. On a pended application, docs say the partner works the sub-merchant (Stax helps the partner). Connect Plus also describes front-loaded underwriting (KYC/KYB and risk review before go-live) versus deferred underwriting it calls instant approvals, where processing can start while verification finishes later.
- Payment methods on the Connect features page: credit, debit, and corporate cards (online and in person), Mastercard Level 2, Apple Pay and Google Pay (online and in person), PayPal and Venmo (online), Buy Now Pay Later (online), ACH (online), HSA/FSA and EBT (online and in person), JCB and UnionPay (in person), and gift cards (in person). The same page lists invoicing, recurring billing, tokenization and account updater, payment links, QR codes, Text2Pay, a mobile SDK for iOS and Android, and Tap to Pay.
- Platforms can monetize with compliant surcharging, custom fees, and other flexible pricing. Residual-report docs describe sub-merchant go-to-market fees as flat rate or interchange-plus, a partner buy rate in basis points plus cents per transaction from the Platform Services Agreement, and a revenue-share split with Stax. Custom fees must be enabled on the partner account. Docs say they cannot be used on surcharged transactions, trust accounts, Apple Pay, Google Pay, or card-present. Stax does not publish a public Connect platform buy rate. Stax Pay publishes merchant subscription pricing separately. This listing does not repeat a rate card.
- Funding and routing on the features page: split funding to multiple accounts, same-day or next-day deposits. Funding docs are more specific. Sub-merchants are paid on the same net-funding pipeline as any Stax merchant (authorize, daily batch, settle, deduct fees and holds, ACH payout). Typical card deposits are 2 to 5 business days. ACH is typically about 5 business days, with banks taking up to 10 to fully clear. Default batch cut-off is 8 PM ET. Deposits skip U.S. bank holidays. Reserves and risk holds can withhold funds.
- Integration is a REST API plus JS and Python SDKs, a mobile SDK, and webhooks. Partners use a Partner API for enrollment and a Merchant API for transactions and related objects. Command Center covers enrollment, transactions, disputes, deposits, residual reports, and branding. Docs mention optional SSO into Stax Pay for the merchant dashboard. White-label options include the Stax Pay portal, the full API, or hybrid.
- PCI: docs say Stax is a Level 1 PCI Service Provider and uses TLS 1.3. The features page lists Level 1 PCI compliance. Merchant-portfolio PCI is run through Aperia Compliance (white-labeled portals, SAQ workflows, ASV scanning).
- Current Connect and case-study pages name Sera (field service), ClientTether (franchise CRM, Connect Plus), and Fishbowl (Connect Plus program) as software partners.
Sources: staxpayments.com, Stax Connect, Embedded payments, Connect features, ISV payment processing, PayFac as a service, Stax Connect Plus, SaaS platforms, Pricing, About Stax, Partner with us, Press and awards, Request a demo, Stax Pay, Connect, and Bill, Managed PayFac, Stax Processing, 10 years, Sera, ClientTether, Connect overview, Enrollment methods, Underwriting, Sub-merchant funding, PCI, Partner PCI / Aperia, Partner API keys, Partner sandbox, Custom fees, Residual reports.
Honest verdict
Stax Connect is the listing to read when the job is high-touch embedded payments for a US (and, on Stax’s processing announcement, Canada) vertical platform: white-label enrollment, Stax as the facilitator in the managed models, and a partner team that will help sell and support payments, including a named referral program in Connect Plus. Live processing waits on a sales conversation, a contract, and implementation. Docs put the average build at 45 days.
What it is not: a public self-serve start, a published interchange-plus buy rate you can treat as yours, or a documented path to become the licensed PayFac on the same stack with a published timeline. Platform pricing sits in the contract (buy rate and revenue share). If the job is payments revenue this quarter without a sales conversation, Stripe Connect is the simpler public path. If the job is a published buy rate with the vendor remaining the facilitator and no path to become the PayFac, Rainforest is the write-up that states that. If the job is residual economics you might own later as the licensed party, Finix and Worldpay for Platforms are the listings that state that path. If the job is a consultative ISV program on Stax’s own processing stack, with referral through managed PayFac and a named traditional PayFac option, start here.