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The 8 Best Payment Gateway & Credit Card APIs For Developers

When you're ready to dive into the world of credit card APIs, you'll want to compare and contrast the developer tools provided by payment services providers.

    Chris Motola
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Advertiser Disclosure: Our unbiased reviews and content are supported in part by affiliate partnerships, and we adhere to strict guidelines to preserve editorial integrity.
Payment API

If you’ve ever run into the limitations of your prefabricated payment infrastructure, it may be time to consider using a payment API. With a payment API, developers on your team can create a custom payment processing setup more specifically tailored to your needs. Below, we’ll look at some versatile payment APIs and their use cases.

Remember, it’s important to evaluate payment APIs not just by their features, but also by how much they cost, how secure they are, and how troublesome they may be to use.

Keep on reading to find out more!

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What Is A Payment API?

A payment API, or application programming interface, allows businesses to use infrastructure and functionality belonging to payment processors to build their own custom payment interfaces.

What Can You Do With A Payment API?

With payment APIs, you don’t have to build a payment processing infrastructure from the ground up, which saves time. You also don’t have to accept the limited configurations some payment processors offer with an “out of the box” approach, which gives you greater control over your customers’ experience.

Here are some examples of what you can do with a payment API:

9 Best Credit Card & Payment APIs For Developers

Payment APIs are a feature provided by a payment processing company or payment gateway, so you’ll need to subscribe to the service to access the API. Below, we’ve listed some of the best credit card processing companies and related services that come with excellent payments APIs.

1. Square: Best For Breadth Of Features

Square



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Pros

  • Predictable flat-rate pricing
  • No long-term contract
  • Enables omnichannel selling
  • Public documentation

Cons

  • Account stability issues
  • Not suitable for high-risk industries

Square Features

Square is a “full-stack” payment service that combines third-party processing with gateway functionality. Square has built up an enormous platform that provides a variety of tools to both eCommerce and brick-and-mortar businesses — including marketing, loans, loyalty programs, productivity, inventory, etc. — on top of processing card transactions. API features include support for:

  • Credit & debit cards
  • ACH
  • Google Pay
  • Apple Pay
  • Payouts
  • Invoices
  • Inventory control
  • Customer management
  • Loyalty programs
  • Booking
  • Team management

Square Pricing

  • Card-present: 2.6% + $0.10
  • Card-not-present: 2.9% + $0.30
  • Keyed-in: 3.5% + $0.15
  • ACH: 1% (min. $1)

Where Square Really Shines

Square is more or less synonymous with “quantity of features.” You’ll get a lot of functionality out of this processor, and all without paying a monthly fee.

As you may expect of an ecosystem as large and complex as Square’s, several different Square APIs allow developers to access different parts of the processor’s infrastructure. Thankfully, Square provides an API Explorer to help you find what you need. Square provides ample documentation on its developer site, custom SDKs, and a sandbox to make development easier.

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2. Host Merchant Services: Best For Customer Service

Host Merchant Services



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Pros

  • Transparent interchange-plus pricing
  • No long-term contracts
  • Good customer support
  • No monthly minimums

Cons

  • Can be expensive for low-volume merchants

Host Merchant Services Features

While it may not be as well-known a name as Square or Stripe, Helcim is an all-around excellent payment processor with an API that covers most of the bases.

  • Credit & debit cards
  • ACH
  • Google Pay
  • Apple Pay
  • EBT
  • Inventory management

Host Merchant Services Pricing

Note, prices below are for transaction volumes above $10,000 per month. Rates are higher for lower volume businesses.

  • Monthly fee: $14.99
  • Retail: Interchange + 0.25% + $0.10
  • Restaurant: Interchange + 0.2% + $0.09
  • eCommerce: Interchange + 0.35% + $0.25

Where Host Merchant Services Really Shines

Host Merchant Services offers interchange-plus pricing to all of its clients, with guaranteed rates for the life of the account.

Host Merchant Services gets high marks for its customer service, which also extends to its developer support and easy-to-use API.

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3. Stripe Payments: Best For Developer Resources

Stripe Payments



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Pros

  • Predictable flat-rate pricing
  • No long-term contract
  • Excellent developer resources
  • Multicurrency support

Cons

  • Account stability issues
  • Not suitable for high-risk industries

Stripe Features

Stripe combines the functionality of a third-party payment processor and a gateway into a single package. This will be convenient for many businesses provided they don’t already have a merchant account that they want to hold onto, as Stripe doesn’t let you use its gateway à la carte; it’s all or nothing. Stripe’s API is deep and versatile, especially when it comes to eCommerce. Features include:

  • Credit & debit cards
  • ACH
  • Google Pay
  • Apple Pay
  • Invoices
  • International currency support
  • International payment method support
  • Account routing by currency

Stripe Pricing

  • Card-present: 2.7% + $0.05
  • Card-not-present: 2.9% + $0.30
  • ACH: 0.8% (max. $5)

Where Stripe Really Shines

When it comes to developer support, Stripe is pretty close to the gold standard for payment processors. The online documentation is exhaustive, easy to parse, and full of readily accessible code snippets in each of the server-side languages it supports (Ruby, Python, Java, PHP, Node.js, Go, and .NET). Stripe also has links to boilerplate projects you can clone and build upon. If there’s a chink in its armor, it’s that Stripe doesn’t provide a sandbox per se, although it does provide faux credit card numbers that you can use to test out your code.

While Stripe has generally been focused on eCommerce, developers may want to test out Stripe Terminal for POS transactions.

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4. Helcim: Best For Easy Scaling

Helcim



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Pros

  • Transparent interchange-plus pricing
  • No long-term contracts
  • Good developer resources
  • Accepts international payments

Cons

  • Not suitable for high-risk industries

Helcim Features

While it may not be as well-known a name as Square or Stripe, Helcim is an all-around excellent payment processor with an API that covers most of the bases.

  • Credit & debit cards
  • ACH
  • Google Pay
  • Apple Pay
  • Invoices
  • Inventory management
  • Support for Canadian payment methods
  • Customer management
  • Card vault

Helcim Pricing

Note: rates posted below are for businesses processing less than $25,000/month. Rates will be lower for businesses processing more than $25,000/month

  • Card-Present: Interchange + 0.3% + $0.08
  • Card-Not-Present: Interchange + 0.5% + $0.25

Where Helcim Really Shines

Helcim is one of our favorite payment processors, and it’s not too hard to see why. Helcim offers transparent interchange-plus processing, no long-term contracts, and extensive fee disclosures. Not only that, but it also scales well with business growth and can handle international payments.

Compared to some of the other services on this list, Helcim’s developer tools fall somewhere in the middle of the pack. They’re more than serviceable, however, with a folder-like layout and ample screenshots. The Helcim API is a RESTful API and can be used with any language that can make an API call. In an interesting desktop layout choice, code samples live just offscreen and can be slid on or off the center of your screen with a click.

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5. Authorize.Net: Best Payment Gateway

Authorize.Net



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Pros

  • Versatile payment gateway
  • Excellent customer support
  • Live console available in the documentation
  • Excellent developer resources

Cons

  • It can be expensive if not bundled
  • It is not a standalone solution

Authorize.Net Features

Most of the other services on this list have been payment processors. Authorize.Net, however, is a standalone payment gateway offered by Visa. You’ll often see it bundled with other services (which is how we’d recommend you use it). Remember, you’ll still need a merchant account/payment processor to process credit cards with Authorize.Net.

  • Credit & debit cards
  • ACH
  • Google Pay
  • Apple Pay
  • Customer information management
  • Syncs with Quickbooks
  • Advanced fraud detection
  • International currency support

Authorize.Net Pricing

Note, Authorize.Net pricing varies depending on the services it’s bundled with. Below is the cost of the gateway-only option, which is in addition to any fees charged by your payment processor.

  • Monthly fee: $25
  • Transaction fee: $0.10

Where Authorize.Net Really Shines

As a payment gateway, Authorize.Net can connect your online store to your payment processor, provide support for multiple currencies, add security features, provide recurring billing services, and enable echeck processing.

In terms of developer resources, Authorize.Net may be one of Stripe’s closest rivals. There’s a ton of documentation, including API references, developer guides, and a collection of PCI-compliant tools called the Accept Suite. Most of it is publicly viewable, so you can check it out before you commit to anything. Much of the documentation contains an API live console, so you can test out snippets of code without leaving the resources.

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6. Stax By Fattmerchant

Stax by Fattmerchant



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Pros

  • Transparent membership pricing
  • No long-term contract
  • Stax Pay integrated payments processing platform
  • Public documentation

Cons

  • Not suitable for low-volume businesses
  • Some billing issues reported

Stax Features

Stax offers subscription-based pricing, which eliminates the percentage markup over interchange rates that you’re typically charged when you swipe a credit card. You’ll still have to pay the interchange fees, which your merchant account provider can’t do anything about, but if you’re looking for predictable, volume-friendly pricing, Stax is a solid option.

Stax Pricing

  • Monthly fee: $99, $159, or $199/month
  • Card-present transactions: Interchange + $0.08
  • Card-not-present transactions: Interchange + $0.15

Where Stax Really Shines

The Stax API provides SDKs for Javascript and Python, though the RESTful API can be used with any language that can make API calls. One of the best things about Stax’s approach is how quickly you can set up an API sandbox to test out its features. You’ll be able to work payment processing into your existing software without having to worry about PCI compliance. The Omni Mobile SDK supports Android and iOS development, allowing you to add tokenized payment methods to your apps.

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7. Dwolla: Best For Standalone ACH Processing

Dwolla



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Pros

  • ACH and peer-to-peer transfer support
  • Excellent developer resources
  • Pay-as-you-go plan available
  • Extensive customer support for paid plans

Cons

  • Can be expensive
  • No credit or debit card support

Dwolla Features

Dwolla isn’t a merchant account provider or a third-party processor. In fact, it’s not a service that processes credit card transactions at all. What Dwolla does offer is a way to facilitate accepting ACH payments between two parties with minimal hassle. It also allows for additional peer-to-peer and bank transfers with its more expensive plans.

  • ACH
  • On-demand payments
  • Bank account balance checks
  • Intra-network transfers

Dwolla Pricing

  • ACH (Pay-As-You-Go Pricing): 0.5% (min. $0.05, max. $5)

Where Dwolla Really Shines

For developers, Dwolla offers a sandbox environment that is a complete replica of its production environment, providing a low-risk way to learn the ins and outs of the platform. The company’s online documentation is pretty deep, offering guides and references, as well as tools and SDKs (a helper library, for example). If you’re interested, you can even apply to be in Dwolla’s Integration Partner Program; just be aware that this requires you to follow Dwolla’s guidelines and best practices.

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8. Braintree: Best For PayPal Integration

Braintree Payment Solutions



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Pros

  • Predictable flat-rate pricing
  • Excellent developer resources
  • Integrates with PayPal

Cons

  • Overpriced gateway only option
  • Not suitable for high-risk industries

Braintree Features

Braintree is part of the PayPal payment services family, along with sister services PayPal and Venmo. It does, however, function semi-autonomously from the other companies and has a slightly different focus.

Braintree Pricing

  • Credit & debit cards: 2.59% + $0.49
  • ACH: 0.75% (max. $5)

Where Braintree Really Shines

At first glance, Braintree’s profile is very similar to Stripe’s — they both combine payment services and gateway functionality, with an eye toward international eCommerce. There are two important differences at this level, however. The first is that Braintree provides a merchant account rather than third-party processing, so you’re getting better account stability, but you should expect to have to jump through some additional hoops and wait times to set it up. And unlike Stripe, it is possible just to use Braintree as a payment gateway if you already have a merchant account. I wouldn’t recommend this, though, as using Braintree’s gateway à la carte is more expensive than most other independent gateways.

For developers, Braintree provides sandbox accounts to explore the service’s functionality. The online documentation is extensive if not quite as slickly presented as Stripe’s — you have to toggle between programming languages at the top of each page rather than each code snippet, for example. The payment API reference section for developers is well laid out, however, making it easy to look up the methods you’ll need when you need them.

Get Started With Braintree Payment Solutions

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What To Look For In A Payment Processor API

What makes a good payment processor API? There are a few factors I’d keep in mind when you’re looking for a developer-friendly payment processor.

  • Does it offer support for multiple payment methods? While this may not be the case for every business, one of the most common reasons to use an online payment API is to expand and customize the payment methods you can offer your customers.
  • Is it customizable? All payment APIs offer some customization options, but does it just allow you to tinker around the edges, or does it offer enough depth to enable you to build what you want to build?
  • How is the pricing? Pricing is still the name of the game, no matter how much hacking you plan on doing. Make sure the provider’s pricing scheme works with your transaction volume and, preferably, allows for month-to-month contracts.
  • Is it secure? Most of the services above use some form of tokenization, so credit card information never ends up residing on your machine. Depending on the company, your PCI responsibilities may vary, so make sure you read through their documentation to find out what they take care of and what they don’t.
  • Does it have good and visible documentation? Many payment service providers offer payment APIs, but many of them hide them from the public. As a rule, I think it’s a good idea to be able to skim their documentation and get a sense of whether it’s a tool you want to work with.
  • Does the service provide SDKs and useful tools? Your mileage may vary here depending on your preferences, but some developers may appreciate having custom libraries and other labor-saving perks available to them.
  • Does it have an active community? Poke around the forums and see how active a developer community the product has. The more active it is, the more likely you’ll be able to have questions answered quickly and be able to make use of existing integrations and code.

Payment Processing Costs & Payment APIs

While some APIs are free to use, that’s not the case when it comes to payment processors. If you’re using a payment API, that usually means you’re going to have to be a customer of that payment processor.

That said, costs will vary greatly depending on the payment processor. Some processors, such as Stripe, will give you access to their API as part of the basic service. Since it’s a month-to-month service with no monthly fee, you’ll only pay the transaction costs, plus any premium features you sign up for. With other payment processors, the API may only be available if you are buying a premium plan.

Costs for payment API usage may include:

  • Transaction Fees: This is the amount of money that will be deducted from each of your sales. This amount will vary by payment method. While it’s usually the same regardless of whether you’re using an API or not, some APIs may allow you to use surcharging to pass on some costs to your customers.
  • Monthly Fees: These are membership fees you pay to keep your account going. Not all processors charge monthly fees. Some will only charge monthly fees for premium plans.
  • Gateway Fees: APIs are frequent functions of payment gateways. Some payment processors have integrated payment gateway APIs, while others use third-party gateways. Be aware of any additional monthly or transaction fees you have to pay to use a payment gateway.

How To Choose The Best Payment Gateway API For Your Needs

Now that we’ve covered some of the heavier hitters in the payment processing API department, you should be able to dig in a little further and match their capabilities to your needs.

Remember that a service that is the best for one company may be an awkward fit for another. Take stock of your developers’ strengths and encourage them to poke around publically available documentation; they can give you a good idea of whether the platform can be hammered into the shape you want.

If you’re going to be tinkering with a payment API, it might be a good time to brush up on PCI compliance and security features, such as credit card tokenization and fraud detection. If you’re looking to customize your payment workflow, you may also want to read up on everything you need to know about alternative payment methods.

Payment API FAQs

What is API payment integration?

An API payment integration allows an existing application to utilize an externally hosted payment processing service. For example, an API payment integration can be used to process credit cards without storing any information locally.

What is API payment processing?

API payment processing allows companies to import functionality from existing payment processing services into their local applications.

What are the benefits of a payment gateway API for developers?

A payment gateway API allows developers to build payment processing functionality into their software without having to design and code a system from scratch. It also offers security and liability advantages as customer credit card information doesn’t need to be stored on local servers.

How does a payment API work?

A payment API is essentially a set of payment processing-related functions that are available to be called by external programs such as the shopping cart of an eCommerce business.

In Summary: 9 Best Credit Card & Payment APIs For Developers

  1. Square:
    • Available in US, Canada, Australia, Japan, UK, Ireland, France, & Spain
    • Good documentation
  2. Host Merchant Services:
    • Available in US
    • Good documentation
  3. Stripe Payments:
    • Available in 47 countries
    • Excellent documentation
  4. Helcim:
    • Available in US & Canada
    • Good developer tools
  5. Authorize.Net:
    • Available in US, Canada, UK, Europe, & Australia
    • Excellent documentation
  6. Stax by Fattmerchant:
    • Available in US
    • Excellent documentation
  7. Dwolla:
    • Available in US
    • Excellent documentation
  8. Braintree Payment Solutions:
    • Available in US, Canada, Australia, Europe, Singapore, Hong Kong SAR, Malaysia, New Zealand
    • Excellent documentation
Chris Motola

Chris Motola

Expert Analyst & Reviewer at Merchant Maverick
An expert in personal and business loans and financial health, Chris Motola has been writing about small business finance and payments for over 5 years. He has been cited in various industry publications, including Forbes Advisor, GoBankingRates, and Medium. Chris is a graduate of the University of Central Florida.
Chris Motola
View Chris Motola's professional experience on LinkedIn.

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Merchant Maverick’s ratings are editorial in nature, and are not aggregated from user reviews. Each staff reviewer at Merchant Maverick is a subject matter expert with experience researching, testing, and evaluating small business software and services. The rating of this company or service is based on the author’s expert opinion and analysis of the product, and assessed and seconded by another subject matter expert on staff before publication. Merchant Maverick’s ratings are not influenced by affiliate partnerships.

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