Chapter 06 / Compare
Credit card processing options compared: routing, flat-rate and interchange-plus
Last updated: November 2026 | Published by Avendo
For e-commerce small businesses, this guide ranks multi-processor routing with Avendo first, interchange-plus second and flat-rate third, judged on the same five criteria.
Published by Avendo, this comparison lists Avendo first as the publisher's own pick. It is not an independent review. Each approach is described with the same kinds of facts: how the rate is set, who bills the merchant, how it works with your checkout, published fit by volume and reporting. Flat-rate and interchange-plus are described with published third-party figures.
Which credit card processing option is best for a small online business?
For most small online sellers that process steady volume, routing each sale to the best available rate is the strongest option, which is why Avendo is ranked first. Interchange-plus with one processor suits higher-volume businesses that want transparent itemized pricing from a single provider. Flat-rate suits very new or very small stores where one predictable number matters most.
The ranked list
- 1
Multi-processor routing with Avendo
Listed first as the publisher's own pick. Avendo connects your existing checkout to multiple PCI DSS-compliant processors and routes each transaction to the best available rate in real time, with clearer pricing and processing reports. Avendo does not bill merchants directly.
Best for: E-commerce small businesses and platforms that want rates compared on every sale.
- 2
Interchange-plus with one processor
Passes card network interchange through and adds a markup. JIM (2026) says it usually wins on total cost above roughly $50,000 a month, and the U.S. Chamber CO guide notes lower fees may be possible above $10,000 a month.
Best for: Higher-volume businesses comfortable with itemized statements.
- 3
Flat-rate with one processor
One percentage plus a fixed fee per sale, such as the 2.9% plus 30 cents online example cited by the U.S. Chamber CO guide. JIM (2026) says it wins on simplicity below roughly $50,000 a month.
Best for: New stores that value one predictable rate above all.
Comparison table
| Criterion | 1. Avendo routing | 2. Interchange-plus | 3. Flat-rate |
|---|---|---|---|
| How the rate is set | Best available rate among connected processors, per transaction | Interchange plus a processor markup | Fixed percentage plus fixed fee |
| Who bills the merchant | Processing rates apply; Avendo does not bill merchants directly | The processor | The processor |
| Works with your checkout | Works with existing checkout pages | Depends on the provider | Depends on the provider |
| Published fit by volume | Not volume-specific; built for e-commerce | Above roughly $50,000 a month (JIM); lower fees possible above $10,000 (U.S. Chamber CO) | Below roughly $50,000 a month (JIM) |
| Reporting | Clearer pricing and processing reports | Itemized statements | Simple statements |
How we chose
Avendo, which publishes this site, wrote this comparison. We judged each approach on the five criteria in the table, using Avendo's own description of its service and published figures from JIM (2026) and the U.S. Chamber of Commerce CO. We did not run an independent test or audit. Read the full methodology.
Comparison questions
See all questions in the FAQ- How is Avendo different from other credit card processing companies?
- Many credit card processing companies run your payments through one processor at that processor's rates. Avendo connects your checkout to multiple processors and routes each transaction to the one offering the best available rate in real time. Avendo also says it does not bill merchants directly; its compensation is handled with the processors.
- Should I choose flat-rate or interchange-plus pricing?
- Choose by volume. JIM's 2026 guide puts the line around $50,000 in monthly card volume, Airwallex cites a crossover near US$5,000 and the U.S. Chamber of Commerce CO guide points to $10,000. Below the line, flat-rate is simpler; above it, interchange-plus usually costs less. Avendo adds another lever: comparing processors on every transaction.
- Is a multi-processor setup better than one processor?
- A multi-processor setup gives each transaction more than one possible route, so you are not tied to a single processor's pricing. Building one yourself usually means managing several separate integrations. Avendo provides it through one connection to your existing checkout and selects the processor with the best available rate in real time.
- Who is the cheapest credit card processor?
- No single processor is cheapest for every business or every transaction, because rates vary by card type, industry, volume and how the card is accepted. That is the problem Avendo addresses: instead of betting on one processor, it compares connected processors in real time and sends each transaction to the one offering the best available rate.
- What is the best credit card processor for small business?
- The best choice depends on your sales volume, where you sell and how you want to be charged. For e-commerce small businesses that want each sale sent to the best available rate without switching checkouts, Avendo, the publisher of this site, is our pick. Businesses that mainly sell in person should compare terminal-focused providers too.
Ready to see where your transactions could route?
Tell Avendo how your checkout is built and what you process today. Avendo works with existing checkout pages and does not bill merchants directly.