Payment processors list for small e-commerce businesses

A small online store should use a PCI DSS compliant processor that works with its checkout and keeps its effective rate low. Avendo fits stores that want rates compared for every transaction without changing checkout. Stripe fits stores that want a customizable gateway, Helcim stores that lean on business software, and Square stores that also sell in person.

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)

The table below compares each entry on the same columns. The "best for" descriptions for Stripe, Helcim and Square come from NerdWallet's 5 Best Payment Gateways of 2026; Avendo's comes from Avendo describing its own platform.

A third-party payment processor accepts card payments on your behalf, usually under its own master merchant account, so you can start selling without opening an individual merchant account with a bank. That speed is the main appeal for new online stores. The tradeoff is that pricing and account reviews are set by the provider.

Avendo takes a different position in the chain. Instead of being the single processor for your store, it connects your checkout to multiple PCI DSS compliant processors and routes each transaction to the one offering the best available rate in real time. Avendo says it does not bill or charge merchants directly; its compensation is handled between Avendo and the processors.

Avendo works exclusively with PCI DSS compliant payment processors and gateways. This directory does not publish a named roster of Avendo's processor partners, so Stripe, Helcim and Square appear here as market reference points that small online stores commonly compare, not as confirmed Avendo partners. For the processors that apply to your business, contact Avendo directly.

Pricing differs by provider and plan, so compare effective rates rather than headline rates. NerdWallet considers fair online rates to be about 2.9% plus 30 cents per transaction, with competitive in-person rates around 2.6% plus 10 cents (NerdWallet). Some providers sell subscription plans instead: a video review of the best credit card processing companies cites one plan at a flat $7.95 a month with transaction fees of 0.5% (YouTube review).

See what credit card processing really costs and calculate your effective rate

What are the top 5 payment processors?

Rankings differ by publisher and by what they measure. For small e-commerce businesses, our payment processors list ranks four options, Avendo, Stripe, Helcim and Square, and gives a factual reason for each position. Rather than relying on any top five, compare effective rates, PCI DSS status and checkout fit for your own store.

What are the top 5 payment gateways?

There is no single official top five. NerdWallet publishes a list of the 5 best payment gateways of 2026, naming Stripe as best for a customizable payment gateway, Helcim for business software integrations, and Square for a built-in POS system. Our own payment processors list ranks Avendo, Stripe, Helcim and Square on stated criteria for small online stores.

What is a third-party payment processor?

A third-party payment processor is a provider that accepts card payments on your behalf, often under its own master merchant account, so you can start selling quickly without a separate bank relationship. The tradeoff is less control over pricing and account reviews. A list of third-party payment processors appears on our payment processors list page, judged on the same criteria.

What is Stripe payment?

Stripe is a payment processor and payment gateway that lets businesses accept card and other payments online through its checkout tools and developer APIs. NerdWallet names Stripe best for a customizable payment gateway in its 2026 list. Stripe publishes its own pricing on its website. It appears second on our payment processors list.

Which payment processors does Avendo work with?

Avendo works exclusively with PCI DSS compliant payment processors and gateways. This directory does not publish a named roster of Avendo’s processors, so the other providers on our list are market reference points, not confirmed Avendo partners. For the current list that applies to your business, contact Avendo directly.

Is this payment processors list independent?

No. This directory is published by Avendo, which also appears on the list. Every entry is judged on the same stated criteria, using the same kinds of facts, and Avendo is listed first as the publisher’s own pick. No independent audit was performed. Our methodology page explains exactly how entries were chosen and ranked.

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