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Stax Payments

Overall Rating

4.7/ 5.0

In-Depth Analysis



Ease of Use






Stax is a Florida-based company that provides credit card processing services for merchants of all sizes. Stax, formerly known as Fattmerchant, is now commonly referred to as Stax by Fattmerchant and is a payment processor offering an integrated payments platform. It includes merchant accounts, e-commerce, mobile processing, inventory management, invoicing, reporting, and more.

The company offers a flat-fee subscription-based pricing model to save merchants on their credit card processing fees. The company’s monthly subscription fees range from $99 to $199. Stax offers a “one-stop shop” model with customizations to fit the needs of businesses of all types. The pricing model provides value to merchants, particularly e-commerce merchants, who have historically been excessively priced by payment processors. Stax is taking a page from Host Merchant Services’ book by offering the sector competitive pricing and top-notch quality service. The company provides volume discounts for high-volume businesses; the more a business processes, the lower the percentage of overall card payment volume they pay.

Stax states on its website that it has processed over 23 billion dollars in payments for over 22,000 customers, having grown around 500% over three years up to early-2022. Stax is part of a growing cohort that is starting to offer a flat monthly fee and fixed per-transaction fee, with no percentage-based markup on top of the interchange fees. The company offers merchant accounts through mobile phone processing and a virtual terminal for e-commerce merchants. The Stax mobile app, available for iOS and recently released for Android, can be used as a standalone solution or integrated into a multichannel platform for card present and card not present transactions. The app syncs transactions, drafts, catalog items, and real-time inventory updates across all devices, including the virtual terminal

Stax is a reseller of payment processing services of Vantiv, which was rebranded as Worldpay after the former acquired the latter. However, the company offers these services without any long-term contract or additional fees. Stax’s acquiring bank is listed as Fifth Third Bank.

Stax History and Founder

Brother and sister duo Sal Rehmetullah and Suneera Madhani founded Stax, formerly known as Fattmerchant. Suneera is currently the company’s CEO, while Sal is the President. The company was established in 2013 but began operations in 2014. Over the past few years, Stax has been on a capital-raising rampage, with total funding of more than $263 million over five rounds of funding since 2015 from well-known venture capitalists such as HarbourVest Partners and Greater Sum Ventures, valuing the company at a highly coveted unicorn status, a company value at more than $1 billion.

Stax raised seed capital of $850 thousand in 2015, led by early-stage accelerator fund venVelo. In May 2016, the company raised Series A funding of $1.4 million, led by growth-stage private equity firm Fulcrum Equity Partners.

In July 2018, Fulcrum Equity Partners again led a venture funding round, this time the late-stage Series C, of $10.5 million

2021 was a busy year of acquisitions for Stax. The company acquired Fusebill, which offers automated invoicing, billing, and collections services for subscription-based businesses. In November of that year, Stax acquired CardX . This firm specialized in automated surcharging and made a name for itself by forging ahead into uncharted territory by providing the niche payment service when the sub-type was both contentious and riddled with legal uncertainty.

Months later, in March 2022, Stax raised a massive $245 million in a Series D funding round led by renowned venture capital firms such as HarbourVest Partners and Greater Sum Ventures, valuing the company at $1 billion, a rarity among minority-led businesses.

What Is Stax Best At?

Stax seems to have built a niche product for which customers have swarmed to the service provider. Businesses that can benefit from the pricing model have signed up in droves, helping the company grow 500% over three years as of early-2022.

Beyond the fixed fee pricing option, the model offers a distinct level of peace of mind through the simplicity of what is being billed. An interchange without any markup and no additional fees, which businesses may need to keep an eye on to control.

So, more than anything, Stax is best known for the pricing model and the savings it can help businesses accrue, as long as they have a sufficient amount of processing volume to benefit from the pricing arrangement offered.

Stax Products and Services

Stax has various solutions for businesses, ranging from payment processing to mobile and traditional point of sale solutions, along with a host of tertiary services such as integrations and numerous eCommerce and analytics-related options.

The breakdown of the company’s flat-fee subscription options is as follows:


Growth Plan

Pro Plan

Ultimate Plan


$99 per month

$159 per month

$199 per month

Customer Experience

Ticketed Support

Ticketed Support

Relationship Manager

ACH Payment Processing




Reporting & Analytics Level




Invoicing functionality




Cards On File Options




Recurring Payments enabled




API feature




Automatically update stored Customers' Credit Card data




One-Click Shopping Cart & Catalog Management




Transactions and Customers Data Exports




Payment Processing – Stax does not process payments and instead partners with WorldPay and resells its service to merchants. Furthermore, unlike many other payment service providers, such as Block, Stax is not a payments aggregator. Stax customers get their merchant ID when setting up a merchant account through Stax.

Point of Sale and Mobile Apps

Point of Sale terminals – Stax has many partnerships to provide merchants with the point of sale solutions, offering a range of countertop terminals from leading brands, providing merchants with a large choice of payment devices. If merchants own their terminal, Stax can reconfigure the machine to make it compliant for use with Stax at no cost. Additionally, the company sells POS solutions for a full outright purchase, instead of offering equipment leases for these solutions.

Paying for a point of sale (POS) solution upfront in full can be more cost-effective in the long run than leasing one. When you buy a terminal, you own it outright, so there are no recurring monthly or annual costs. In contrast, with a lease, you typically make regular payments over a specified period, which can add up over the life of the lease. Most of the time, those recurring monthly or annual costs end up being many multiples of the cost of the equipment.

Mobile POS – It’s hard to function efficiently in our personal lives without our smartphones and the numerous apps we need daily. That fact is even more pertinent when one is running a business. It can be highly productive if merchants can access Stax’s platform via an app that would let them support EMV and mobile wallet payments and allows them to do the same tasks they can do via their desktop or laptop, such as access to invoicing and inventory features, without any additional costs. That is precisely what the Stax Pay app can do.

Virtual Terminals – Stax’s virtual terminal is a cost-effective solution for businesses that primarily process payments through a computer, such as in an office or for phone orders. The virtual terminal has a customer database, invoicing, and inventory management features. It can also be connected to Stax’s credit card readers, allowing you to benefit from in-person rates. Stax Pay’s Growth plan offers essential website payments feature if you don’t need a complete shopping cart but still want to accept online payments.

Shopping Carts – Stax offers a hassle-free payment solution for online sellers with this offering. Often when making a purchase online, the customer may need to leave the site to complete the transaction. The shopping cart functionality available from Stax allows merchants to embed the feature on their own websites. This has a meaningful impact on businesses beyond eCommerce merchants. More and more businesses are processing payments online and often need to save the payment details for future payments, as is often the case for recurring payment such as subscriptions. Managing that process end-to-end allows for a more seamless and efficient experience as customers see a uniform design and can access their payment credentials without having to reenter it next time. All without having to leave the merchant’s platform to complete the transaction.

Stax API – In business parlance, data is the new oil. As a result, tools have greatly flourished over the past decade to extract and use that data. Even businesses that operate at a smaller scale have increasingly started to ask what type of API functionality and software development kits would be available with a company’s service. Although the tools offered by Stax are not as open as Stripe or Square, they include a wide range of features, such as processing payments via JavaScript apps, an invoice function that redirects customers to a Stax-hosted site, and development documentation to implement mobile payment processing.

Tertiary Services Include:

Stax Pay –an integrated payment platform that centralizes all transactional information. The platform has a web-based dashboard that allows merchants to use it to manage inventory, a customer database, dispatch invoices, and have access to basic reporting functionality. The best benefit of this combined portal is that merchants can invoice their customers seamlessly by accessing the database of customer data and the item key of their uploaded product list. Advanced reporting features can also be added for an additional cost.

Stax Connect – The company also provides a processing package specifically designed for SaaS software platforms called Stax Connect. This offering from Stax is a “fully managed payments facilitation ecosystem for your platform,” but no public disclosure of prices on the company’s website exists. Customers are simply advised to request a demo.

Stax Lending Services – Stax offers multiple products as part of the company’s same-day lending solution. These products include:

  – Term loan – for an amount of up to $10 million for a period of six months to as long as three years

  – Revolving line of Credit – a rolling credit limit for an amount of up to $10 million

  – Advance on receivables – for an amount up to $750,000 for a period of three to twelve month

Stax Pricing and Fees

Stax offers comprehensive merchant services with an integrated payments platform with robust features, including merchant accounts, eCommerce, mobile processing, inventory management, invoicing, and billing, reporting, among many more. The company’s pricing model offers excellent value to many merchants, especially eCommerce merchants who have historically paid exorbitant rates to payment processors. Businesses likely benefit most from Stax’s pricing model are those merchants with high-volume companies that can reap the benefits of discounts offered by a fixed-fee plan rather than a certain percentage of their overall card payment volume as they process more. This pricing dynamic has led to the company’s processing over $23 billion in payments for over 22,000 customers and valuing it at $1 billion by private investors.

The company offers payment processing services as integrated packages, with three monthly subscription plans for businesses processing under $5 million annually and custom quotes for those transaction great than that amount. In addition to the subscription fees, merchants pay per transaction interchange fees + $0.08 per transaction for card-present transactions. That amount jumps to $0.15 per transaction + interchange for card not present transactions. The three subscription solutions offered by Stax are the Growth Plan, Pro Plan, and Ultimate Plan, with each successively being more expensive and feature-rich than the previous one.

Unfortunately, Stax is not for everyone. It is not a cost-effective option for small businesses seeking a multi-functional payment platform. On average, if a merchant’s monthly processing of up to $10,000, Stax’s offering may not best serve such a business, in which exploring alternative platforms for competitive prices that offer similar level of services.

One of the great benefits of the monthly subscription model is that the fee covers almost everything besides payment processing. As a result, merchants who typically incur additional costs for services that are generally part of payment processing are now free of that headache.





Monthly Fee

$99/ month

$159/ month

$100/ month

Swiped/Dipped/Tapped Payment Processing

Interchange + 0% + $0.08/ transaction

Interchange + 0% + $0.08/ transaction

Interchange + 0% + $0.08/ transaction

Card Not Present Payment Processing

Interchange + 0% + $0.15/ transaction

Interchange + 0% + $0.15/ transaction

Interchange + 0% + $0.15/ transaction

ACH transactions

Standard transaction: $0.25/ transaction

Expedited transaction: $1.50/ transaction

Additional fees

Monthly Fee 


Batch Fees


PCI Fees


Set up Fees


Gateway Fee


Early Termination Fee


Given the company’s pricing model, Stax does not impose fees like application fees, account setup fees, or gateway setup fees. However, the actual cost of the gateway provided by third-party vendors, such as or USAePay, may cost additional.

Details Of The Contract Offered and Other Legal Details Of Stax

The standard merchant agreement with Stax via Vantiv is for 36 months and automatically renews for two more years. However, a company representative has confirmed no additional fees for early termination, as mentioned in the merchant application. Additionally, Stax offers a flexible monthly contract without any cancellation fees. As highlighted in our pricing section, the company also states that they do not impose additional costs that should generally be covered as part of payment processing, such as batch fees or recurring monthly or annual charges. That is a welcome reprieve since the standard terms in Vantiv’s agreement include a very punitive form of cancelation fee called liquidated damages, which holds the merchant liable for the number of monthly processing fees for the remainder of the contract.

No class-action lawsuits or FTC complaints against Stax have been identified. Nor has our research turned up any legal cases against the company. However, Stax acquired CardX in 2021, a company involved in several legal cases in defense of their right to use surcharges for “zero-fee” processing.

Although that activity was around a different business activity, the fact that Stax is now the parent company may impact the overall business. However, given that CardX was winning the cases in litigation, it is unlikely to have a material effect on the comprehensive services Stax offers.

Are There Any Complaints About Stax

There have been increasing complaints about Stax’s refusal to provide its merchants with itemized account statements regarding individual transactions and their Interchange fees. Although Stax asserts that the company transparently passes on base Interchange fees, the lack of comprehensive reports makes it difficult to verify the veracity of these claims.

Stax has been accredited with the Better Business Bureau (BBB) since 2020 and currently holds an “A+” rating. Over the last three years, the company has received 29 complaints, with nine related to product or service issues, 12 complaints about billing, and five from sales and advertising issues. Of these complaints, 22 were resolved to the satisfaction of the merchants. The remaining seven either needed to be resolved satisfactorily or had not received a response. That number of complaints is low, given that the company serves over 22,000 customers as of 2022. Furthermore, Stax appears to be making a concerted effort to address those claims, given the high percentage of resolutions to the complaints filed on the BBB website.

Customer Support

24/7 Help & Support

24/7 Live Phone Support
Online Ticketing System via Support Form

Phone Support

24/7 Live Phone Support


Contact through contact form on website available

FAQ and Chat

Live Web Chat Support
Stax Knowledge Base for Business Owners, Software Platforms and Developers


Stax is a Florida-based company founded in 2014 by siblings Sal Rehmetullah and Suneera Madhani. The company offers a range of solutions, including mobile and traditional point of sale, merchant accounts, e-commerce, inventory management, invoicing, and reporting, along with other options. Stax processes payments by partnering with Worldpay and reselling its service to merchants.

The company provides various payment processing services for merchants of all sizes and offers a flat-fee subscription-based pricing model that saves merchants on credit card processing fees. Stax’s business model has helped it grow exponentially and process over 23 billion dollars in payments for over 22,000 customers.

According to our evaluation standards, Stax is a trustworthy merchant account provider with few complaints, despite its recent uptick in complaints that undermine its highly acclaimed pricing model and transparency. They offer transparent and competitive contract terms, making them suitable for both small and large businesses alike. For all merchants, we always recommend; READ THE CONTRAC! That applies no matter how reputable the payment processor is.