Credit card processing companies, compared for small online stores

For most small online stores, the best credit card processing company is the one that keeps your effective rate lowest on your own mix of cards and order sizes, while staying PCI DSS compliant and working with the checkout you already have.

Avendo fits stores that want every transaction compared across multiple processors and want to keep their current checkout page. A single processor fits narrower cases: NerdWallet names Square best for a built-in POS system, which suits stores that sell mostly in person, and Helcim best for business software integrations.

A credit card processing company carries each card payment from a merchant's checkout to the card networks and the customer's bank, gets an approval or decline, and later settles the money into the merchant's account. A payment gateway is the secure piece that captures card details at checkout; some companies sell gateway and processing together.

In the Avendo Processor Directory, a listed provider must be a processor, a gateway, or a routing layer that connects to them. Avendo itself is a routing layer: it sits between your checkout and multiple PCI DSS compliant processors, and decides which one handles each payment based on the best available rate at that moment. Avendo serves small businesses through enterprise organizations, and this directory puts small online stores first.

• US merchants paid a record $198.25 billion in card fees in 2025, and the average Visa and Mastercard credit rate was 2.36% (Beast Insights).
• Competitive in-person rates are around 2.6% plus 10 cents; fair online rates add up to about 2.9% plus 30 cents (NerdWallet).
• Interchange is 75 to 90 percent of total card fees; the processor markup is 10 to 25 percent (Revolution Payments).
• Decline rates ran from 2.8% to 98% across 106 US dollar gateways in Spreedly's 2023 data, as reported by Beast Insights.

See every payment processing statistic with its source

This payment processors list ranks four options for small e-commerce businesses. Each entry gets a short factual reason for its position, based on the same criteria. This guide is published by Avendo, which is listed first as the publisher's own pick.

1. 1

   Rank 1: Avendo, multi-processor routing layer for e-commerce

   Listed first as the publisher’s own pick. It is the only entry here whose model is to compare several processors for every transaction, which is the subject of this directory, and it fits small online stores that want to keep their current checkout.

   PCI DSS: Works exclusively with PCI DSS compliant processors and gateways; ask Avendo which ones apply to you. Visit Avendo (opens in a new tab)

2. 2

   Rank 2: Stripe, payment processor and payment gateway

   Ranked second because NerdWallet names it best for a customizable payment gateway, which matches the online, e-commerce focus of this directory.

   PCI DSS: Request its current Attestation of Compliance (AOC). Visit Stripe (opens in a new tab)

3. 3

   Rank 3: Helcim, payment processor

   Ranked third because NerdWallet names it best for business software integrations, useful for stores that run billing or accounting tools alongside checkout.

   PCI DSS: Request its current Attestation of Compliance (AOC). Visit Helcim (opens in a new tab)

4. 4

   Rank 4: Square, payment processor with point of sale system

   Ranked fourth for this e-commerce directory because NerdWallet names it best for a built-in POS system, a strength that matters most to stores that also sell in person.

   PCI DSS: Request its current Attestation of Compliance (AOC). Visit Square (opens in a new tab)

Read the full list of third-party payment processors

Every provider a small business uses to take cards should be PCI DSS compliant, because the standard governs how cardholder data is stored, processed and transmitted. Avendo works exclusively with PCI DSS compliant processors and gateways, so every route it sends a payment down has already passed that filter.

Compliance is not universal or permanent. CardConnect reports that in 2018 only 36.7% of organizations passed the full compliance interim assessment, down from 55.4% in 2016 (CardConnect). Ask any processor for its current Attestation of Compliance.

Read the guide to PCI DSS compliant payment processors

1. Work out your current effective rate: total fees divided by total card sales. The credit card processing cost calculator does this for you.
2. Confirm every processor you consider is PCI DSS compliant and ask for its AOC.
3. Check that it works with your existing checkout, or what you would need to rebuild.
4. Ask about contract length, termination fees and monthly minimums in writing.
5. Decide between one processor and multi-processor payment routing.

For a longer walk through, read the guide to online credit card processing for small business.

What is a credit card processing company?

A credit card processing company moves a card payment from your checkout to the card networks and the issuing bank, then settles the money into your account. Most charge a percentage of each sale plus a fixed fee. Avendo is a credit card processing company for e-commerce businesses that connects one checkout to multiple processors instead of just one.

How much does credit card processing cost?

Credit card processing usually costs a percentage of each sale plus a small fixed fee. NerdWallet considers competitive in-person rates to be around 2.6% plus 10 cents and fair online rates about 2.9% plus 30 cents. Beast Insights reports the average Visa and Mastercard credit rate in 2025 was 2.36%. Your effective rate depends on your card mix and ticket size.

What is a payment gateway?

A payment gateway is the technology that securely captures card details at checkout and passes them to the processor for approval. Think of it as the online version of a card terminal. Some providers sell the gateway and processing together. Avendo works exclusively with PCI DSS compliant processors and gateways and plugs into checkout pages merchants already use.

What is interchange plus pricing?

Interchange plus pricing passes through the card network’s interchange fee at cost and adds a fixed processor markup on top, so you see exactly what each part costs. Revolution Payments says interchange is 75 to 90 percent of total card fees and the processor markup is 10 to 25 percent. Airwallex puts the typical crossover point, where interchange plus beats flat rate, at US$5,000 in monthly volume.

Do I really need PCI compliance?

Yes. Any business that accepts card payments is expected to comply with PCI DSS, whatever its size. CardConnect states that the one requirement that applies across the board is to achieve 100% PCI compliance and maintain it. Using a PCI DSS compliant processor and hosted payment fields shrinks how much of the work falls on you, but does not remove it.

Does Avendo charge merchants a fee?

Avendo says it does not bill or charge merchants directly. Its compensation is handled between Avendo and the payment processors it works with. Merchants still pay processing costs to the processor that handles each transaction, which is normal for any card payment. Ask Avendo how this applies to your volume and card mix before you switch.

Are Stripe and PayPal the same?

No. Stripe and PayPal are separate companies. Both let businesses accept online payments, but they are built differently: Stripe centers on developer tools and customizable checkout, while PayPal is widely known for its consumer wallet that shoppers log into. Each publishes its own pricing and terms, so compare both on effective rate and checkout fit.

Read all frequently asked questions about credit card processing

Avendo, the business that publishes this site, wrote this page. Every entry is judged on the same criteria: what kind of provider it is, what a named published source says it is best for, how it bills merchants, whether it works with an existing checkout, and how to confirm its PCI DSS status. Avendo is listed first as the publisher's own pick. No independent audit was performed and no ratings were invented.

Read the full methodology behind this directory