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Personal Finance · head to head

Affirm vs Medius

Affirm logo

Affirm

Personal Finance

Buy now pay later app offering short interest-free plans and longer plans that charge real APR interest

From
Free
Rated
-
Full reviewWebsite
Medius logo

Medius

Accounting

Accounts payable automation and supplier payments for mid-market finance teams, Marlin Equity owned

From
On request
Rated
-
Full reviewWebsite

The short version

  • Only Affirm has a free tier, so it costs nothing to try first.
  • Each has a real cost: Affirm longer instalment plans carry real interest, up to roughly 36 percent APR depending on the retailer, item and applicant, which is a genuine borrowing cost that the buy now pay later framing can obscure for shoppers who do not read the terms shown before accepting.; Medius the sourcing, contract and procurement modules are considerably less developed than the AP core, so buying Medius as a full source-to-pay suite means accepting weak upstream tooling.
  • They diverge on capability: Affirm covers Pay in 4, Medius covers Invoice capture and coding.
  • Prices and features above were last checked on 1 September 2026.

Where they differ

Only the attributes on which Affirm and Medius actually diverge.

Attributes where Affirm and Medius differ
AttributeAffirmMedius
Starting priceFreeOn request
Pricing modelFree for short Pay in 4 plans; longer plans carry a disclosed APR up to roughly 36 percent, merchant pays a transaction feequote
Free tierYesNo
PlatformsiOS, Android, WebWeb, iOS, Android
CategoryPersonal FinanceAccounting

Identical on both: user rating (Not yet rated).

What each one covers

Drawn from each product's published feature list. An absence here means we hold no record of it - not that the product lacks it.

Only in Affirm

  • Pay in 4
  • Monthly instalment loans
  • Soft credit check
  • No late fees
  • Affirm Card
  • Pre-purchase terms disclosure

Only in Medius

  • Invoice capture and coding
  • Matching and exception handling
  • Fraud and anomaly detection
  • Supplier payments
  • Approval workflow
  • ERP integration

What people use each for

The jobs each tool is most often brought in to do.

Affirm

  • A shopper financing a large purchase such as furniture or electronics who wants disclosed APR terms compared directly against a credit card before committingnot Medius
  • Someone using the short Pay in 4 plan for a smaller purchase who intends to pay it off within six weeks with no interestnot Medius
  • A borrower who has missed a payment before and specifically wants a lender that does not charge late feesnot Medius
  • A retailer offering point-of-sale financing to reduce cart abandonment on higher-ticket items, in exchange for paying Affirm a transaction feenot Medius

Medius

  • A mid-market finance team where most spend arrives as an invoice with no purchase order to match againstnot Affirm
  • A group with several legal entities on different ERPs that wants one AP process across all of themnot Affirm
  • Reducing invoice fraud exposure with automated detection of supplier bank detail changesnot Affirm
  • Replacing a scanning bureau and a shared AP inbox with automated capture and exception-based reviewnot Affirm

Where each one falls short

Documented limitations, not opinions. Every one is a constraint you would hit in normal use.

Affirm

  • Longer instalment plans carry real interest, up to roughly 36 percent APR depending on the retailer, item and applicant, which is a genuine borrowing cost that the buy now pay later framing can obscure for shoppers who do not read the terms shown before accepting.
  • Even with no late fees, Affirm reports many loans to credit bureaus, so a missed or late payment on a longer plan can affect a credit score in a way the marketing around interest-free short plans does not prepare shoppers for.
  • Approval and APR both vary by individual loan, so the same shopper can be offered interest-free terms on one purchase and a high APR on another, making the cost unpredictable until checkout.
  • Merchants pay a transaction fee to offer Affirm at checkout, a cost typically built into retail pricing, so shoppers who pay by other means still indirectly subsidise the option even if they never use it.
  • The Affirm Card blurs the line between buy now pay later and a general-purpose credit card, and using it for everyday spending on interest-bearing terms can compound borrowing cost in a way a single point-of-sale purchase would not.

Medius

  • The sourcing, contract and procurement modules are considerably less developed than the AP core, so buying Medius as a full source-to-pay suite means accepting weak upstream tooling.
  • Pricing is quote-only and driven by invoice volume, so a business with many low-value invoices pays disproportionately relative to the spend being controlled.
  • Payments are billed on transaction volume separately from the AP subscription, which is easy to omit from a cost comparison against a licence-only AP tool.
  • Private equity ownership since 2017 has produced an acquisition-driven product line, so payments and adjacent capability come from bought-in technology rather than the original platform.
  • ERP integration depth varies sharply by system, and organisations on less common or heavily customised ERPs face integration work that lengthens the implementation.

Pricing, plan by plan

Affirm

Free
  • Pay in 4Free
    • No interest if paid on time over six weeks
    • No late fees for a missed payment
    • Soft credit check at application
  • Monthly instalmentsFree
    • APR disclosed before the loan is accepted, up to roughly 36 percent depending on retailer and applicant
    • Terms from three to 36 months depending on purchase amount
    • Payment history can be reported to credit bureaus

Medius

On request
  • Medius AP Automation$undefined/year
    • Two packaged AP automation tiers
    • Priced by invoice volume and entity count
    • Sourcing, contracts and procurement modules sold separately

Which should you pick?

Choose Affirm if

  • You need pay in 4.
  • You want to start without paying.
  • You work on iOS, Android, Web.
  • You also want monthly instalment loans.
Affirm review

Choose Medius if

  • You need invoice capture and coding.
  • You work on Web, iOS, Android.
  • You also want matching and exception handling.
Medius review

Questions people ask

Is Affirm or Medius better?
Neither clearly leads. Affirm starts at Free and Medius at On request, and user ratings are close enough to be indistinguishable. Choose on capability and platform support.
Which is cheaper, Affirm or Medius?
Affirm has a free tier; the other does not. Paid plans start at Free for Affirm and On request for Medius.
Does Affirm or Medius run on more platforms?
Affirm runs on iOS, Android, Web. Medius runs on Web, iOS, Android.
Can I use Affirm for free?
Yes. Affirm has a free tier, so you can try it without paying. Medius starts at On request.
What is Affirm best used for?
Affirm is most often used for a shopper financing a large purchase such as furniture or electronics who wants disclosed apr terms compared directly against a credit card before committing, someone using the short pay in 4 plan for a smaller purchase who intends to pay it off within six weeks with no interest, a borrower who has missed a payment before and specifically wants a lender that does not charge late fees, a retailer offering point-of-sale financing to reduce cart abandonment on higher-ticket items, in exchange for paying affirm a transaction fee. Of those, a shopper financing a large purchase such as furniture or electronics who wants disclosed apr terms compared directly against a credit card before committing and someone using the short pay in 4 plan for a smaller purchase who intends to pay it off within six weeks with no interest are not what Medius is typically brought in for.
What can Affirm do that Medius cannot?
Affirm covers Pay in 4, Monthly instalment loans, Soft credit check, No late fees. Medius covers Invoice capture and coding, Matching and exception handling, Fraud and anomaly detection, Supplier payments.

Answered from the vendors’ own pages

Affirm: Does Affirm always charge interest?

No, short Pay in 4 plans over six weeks are typically interest-free if paid on time; longer instalment plans of three to 36 months can carry a disclosed APR up to roughly 36 percent.

Medius: Is Medius a procurement suite or an AP tool?

Primarily an AP automation platform with procurement modules attached. If sourcing is your main requirement, look elsewhere.

Affirm: Does Affirm charge late fees?

No, Affirm does not charge late fees for a missed payment, unlike some buy now pay later competitors, but missed payments can still be reported to credit bureaus.

Medius: Who owns Medius?

Marlin Equity Partners, which acquired it in 2017 and has funded several bolt-on acquisitions since.

Affirm: Will using Affirm affect my credit score?

The initial application uses a soft credit check that does not affect your score, but Affirm reports many resulting loans to credit bureaus, so payment history on the loan itself can affect your score.

Medius: How is it priced?

By quote, driven by invoice volume and entity count, with payments billed separately on transaction volume.

Medius: Does it replace our ERP?

No. It sits alongside the ERP and posts approved invoices into it.

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