Methodology
How we chose: the methodology behind this directory
Every provider in the Avendo Processor Directory is judged on the same six criteria, using the same kinds of facts, and Avendo, which publishes the site, wrote this methodology.
Avendo is listed first as the publisher's own pick. Stripe, Helcim and Square are ranked by how closely what NerdWallet says each is best for matches small e-commerce businesses. No independent audit was performed and no ratings were invented.
Guide published by AvendoLast updated
How are entries on the payment processors list ranked?
Entries are ranked by how well their published strength fits a small online store. For Stripe, Helcim and Square we use the "best for" descriptions in NerdWallet's 5 Best Payment Gateways of 2026. A customizable payment gateway fits e-commerce most directly, business software integrations next, and a built-in POS system matters most to in-person sellers.
The criteria
- Provider type
- Processor, gateway, or a routing layer that connects to them.
- Best for
- What a named published source says the provider is best for.
- Billing
- How the provider charges merchants, as it states publicly.
- Checkout fit
- Whether it works with an existing checkout or offers its own tools.
- PCI DSS check
- How a merchant can confirm PCI DSS status.
- Fit for small online stores
- How closely the provider’s stated strength matches e-commerce.
Sources we use
We use providers' own public descriptions, Avendo's description of its own platform, and published industry sources named on each page, including NerdWallet, Beast Insights, Revolution Payments, Swipesum, Airwallex, CardConnect and Exabeam. Each number is quoted as the source published it, with its range and conditions, and is never presented as Avendo's own figure.
Limits
We do not publish ratings, review counts or test results, because none were measured for this directory. We describe competitors only with neutral facts. Pricing changes, so check each provider's current pricing page before you decide. The directory does not state which processors Avendo routes to; ask Avendo for that list.
Common questions
- 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.
- 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.
- 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.
- Who is the biggest credit card processor?
- It depends on the measure: transaction volume, number of merchants, or revenue all give different answers, and rankings shift from year to year. This directory does not rank by size, because size says little about the rate a small store pays. For current size rankings, check a recent published industry report and note which measure it uses.
- What is Avendo?
- Avendo provides credit card processing for e-commerce businesses. Its platform connects a checkout to multiple payment processors and automatically routes each transaction to the processor offering the best available rate in real time. It also gives merchants clearer pricing and processing reports, works with existing checkout pages, and serves small businesses through enterprise organizations. Avendo publishes this directory.
Read all frequently asked questions about credit card processing
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