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For most small businesses, growth is a top goal. If your business is expanding rapidly with high revenues, you'll need a credit card processor that can grow with you. We selected Stax (formerly Fattmerchant) as the best credit card processor for high-revenue businesses with a lot of transactions. Stax keeps customer service and tech support in-house, so you won't experience the inconvenience of dealing with outsourced, third-party representatives. Stax also offers a dedicated account manager to businesses that earn over $500,000 annually, as well as numerous integration options. 

Stax is the best credit card processor for high-revenue small businesses thanks to its flat-rate, tiered pricing and robust features.

With a tiered, flat-rate pricing model, Stax is our top credit card processor for businesses that generate annual revenues of $500,000 or more. Stax features a variety of hardware and point-of-sale (POS) system choices, as well as numerous free integrations. The company also offers add-ons, like the ability to store card information, sales tracking, and brand customization for invoices, receipts and websites. 

We found Stax's user interface to be straightforward, feature-rich and fairly intuitive. The software goes well beyond the technology offered by most payment processors, and Stax boasts better functionality than many POS packages that provide similar capabilities. 

A panel on the left side lists Stax's main features, including report generation, payments, invoices and disputes. The main dashboard displays information such as settlements and deposits, as well as sales and refunds. Stax's advanced customization allows users to edit their display settings for things such as color-coding. 

One popular feature of Stax is its recurring payments system, which allows business owners to securely store payment information and schedule payments down to the exact day. If customers change payment methods, you can simply edit their information rather than set up a new payment profile.

We found the Stax Pay mobile app to be similarly well developed, with a sleek, easy-to-use interface, although some customer reviews complain about technical issues with the mobile card reader hardware. 

All of Stax's systems are PCI compliant with no liability for the business owner, which takes care of a technical challenge that frustrates many small businesses. 

Stax offers a number of card readers for purchase, as well as a variety of payment gateway integrations. Card readers and protection plans range from $9 to $29 per month for each device. Protection plans cover device upgrades and replacements. Stax covers free gateway integration, whereas gateway providers themselves often charge a fee. This is a great benefit of working with Stax, especially if you've already set up a POS system for your business. 

As a Level 1 PCI Service Provider, Stax offers the highest level of PCI compliance. The company tokenizes and encrypts payment data on all devices to protect cardholder data. The information is removed after the completion of the transaction. This secure payment process helps prevent third parties from accessing data or intercepting transaction information. 

Stax integrates with some of the best POS systems, including ShopKeep, Revel and Vend. These integrations are free of charge with Stax, but the POS system may charge its own fees for integration. According to Stax, the company supports approximately 90% of third-party POS systems. Customers are encouraged to reach out directly to Stax to inquire about integration with specific POS systems. 

Tip: Want to learn more about POS systems and how credit card processors integrate with these platforms? Read our guide on how to set up a POS system.

Stax offers 24/7 customer support via phone, email or live chat, and the company covers a broad range of frequently asked questions on its website. 

The Stax Pay mobile app allows small businesses to process transactions, review sales metrics, manage inventory and send receipts. App users can connect a mobile swiper to their tablet or phone via Bluetooth to accept payments. Stax Pay is compatible with iOS and Android devices. Another useful feature is Stax's text-to-pay option, which allows businesses to text customers a mobile-friendly link. Few credit card processors provide this extra feature. 

Stax offers small businesses the option to customize invoices, receipts and payments to match their individual brand, as well as set permissions for other employees. Customers can also seamlessly integrate software such as QuickBooks, Wave, Xero, Mailchimp, HubSpot and Zoho. 

One advantage of Stax over bare-bones credit card processors is that you can send invoices and accept recurring payments. This feature is useful for subscription-based businesses with recurring revenue sources that make payments regularly. Automating recurring payments can help guarantee cash flow and reduce subscriber churn.

Stax is popular for its subscription-based pricing and no additional interchange fees. If your business brings in a consistently large number of sales, Stax's pricing model may come with major savings. The following pricing tiers are available from Stax.

FYI: If your business is not yet at the $5,000-per-month mark, Stax could be one of the most expensive credit card processing companies on our list for you.

Stax does not require a contract or charge an early termination fee. However, it does require 30-day written notice prior to service cancellation. 

Rather than imposing fluctuating fees, Stax charges a flat monthly subscription fee. With a starting monthly rate of $99, the fee is hefty compared with those of other credit card processors on our list. That said, businesses with a large sales volume can actually save with Stax as a credit card processor, because that fixed fee is spread out over many transactions. Additionally, Stax charges fixed interchange rates. 

Stax includes the PCI compliance fee in its subscription price rather than making it an additional fee. This built-in cost is another way Stax beats the competition when it comes to serving large-volume businesses. 

In addition to subscription plans, Stax offers add-on features for every plan. These optional features include custom branding, digital gift cards, same-day funding and a one-click shopping cart. 

FYI: Stax charges a $25 fee for all chargebacks related to customer disputes, regardless of the dispute outcome.

Stax does not require you to buy or lease equipment, and you can use a terminal of your choice. Your hardware requirements depend on the types of payments you wish to accept (in-store, mobile, e-commerce, etc.). 

These are some of the hardware options:

Other mobile readers are available for $75. If you already have equipment, it will likely integrate with Stax. The company says it offers integration with 99% of hardware and software. 

Stax Pay, the company's free integrated payments platform, features a dashboard to view customer data, review inventory, manage invoices, process transactions and handle reporting. 

Add-ons are also available (with custom pricing), including these extras:

While interchange fees don't fluctuate with Stax, you can expect to pay additional transaction fees. Each in-person transaction is an additional 8 cents, while manually entered transactions are an extra 15 cents each. 

To apply for Stax's services, you must get in touch with a sales representative by calling or submitting an online form. A questionnaire will help you determine which package is right for your business, using several criteria, including your business's industry, your personal background and your hardware needs. After that, you will receive a quote for the pricing tier that matches your needs. (Businesses that process more than $500,000 annually can contact the company for a custom quote.) 

Once your application is approved, a Stax representative will introduce you to a dedicated account manager, who will begin the onboarding process specific to your business's needs and walk you through any payment methods you require. 

Stax offers 24/7 customer support via phone, email, fax or live chat. The company also covers a broad range of frequently asked questions on its online knowledgebase. Customers also gain access to a dedicated account manager and in-house technical support. 

The range of Stax's customer service options decisively beats out many alternatives on our list of the best credit card processors. Moreover, we found Stax's customer service representatives to be responsive and knowledgeable about the service's features. 

Although Stax stands apart as one of the most feature-rich offerings, you must be willing to pay up for that functionality. The minimum $99 monthly subscription fee may put the service out of reach for many small businesses on a budget, and customers must purchase their own payment hardware. On user review sites such as Trustpilot, some customers complained about fees for add-ons or price increases. Although Stax offers 24/7 customer service by phone, it may sometimes be understaffed; some reviewers wrote of long hold times and wait periods between messages. 

To conduct our review of Stax's credit card processing service, we arranged a live demo with the Stax team, which gave us a walk-through of the product and conducted a thorough question-and-answer session. In addition, we analyzed Stax's website, marketing materials and customer reviews on the web. To make our decision, we zeroed in on criteria such as affordability, ease of use, and features that are relevant to small businesses. In the end, we chose Stax's credit card processing services as the best for high-revenue businesses because of its tiered, flat-rate pricing model, which allows high-volume businesses to scale without switching providers. 

Fattmerchant is a payment technology company that rebranded as Stax in 2021 to better reflect its position as an overall financial solutions provider. 

Stax's entry-level plan starts at $99 per month. 

There is no early termination fee. You can cancel anytime by calling Stax customer support. 

We recommend Stax by Fattmerchant for …

We don't recommend Stax by Fattmerchant for …

Stax is the best credit card processor for high-revenue small businesses thanks to its flat-rate, tiered pricing and robust features.