The verdict in three sentences
For a London SME, the technical integration of online payments runs between 3,000 and 15,000 EUR depending on complexity, but the dominant 12-month cost remains the PSP commission (1.4 to 2.9 % + 0.25 EUR per transaction). The right choice is decided on monthly volume and payment mix, not on the sticker price. Below 20,000 EUR monthly revenue, turnkey Stripe or Mollie win; above that, rate negotiation becomes the real lever.
What the integration budget actually covers
An integration quote is never just "plugging in" the PSP. It covers the payment funnel, 3-D Secure 2 security, accounting reconciliation and dispute handling. Here are the typical line items in London in 2026 (ballpark).
| Integration item | 2026 cost (EUR) | Timeline |
|---|---|---|
| Standard PSP hookup (Stripe/Mollie) | 3,000 - 6,000 | 2-3 weeks |
| Custom payment funnel + 3-D Secure 2 | 5,000 - 9,000 | 3-4 weeks |
| Automated reconciliation (ERP/accounting) | 2,500 - 5,000 | 2-3 weeks |
| Dispute + refund management | 1,500 - 3,500 | 1-2 weeks |
| Multi-currency + wallets (Apple/Google Pay) | 2,000 - 4,500 | 2 weeks |
| Testing, UAT, go-live | 1,500 - 3,000 | 1 week |
A "Starter" project (standard PSP + wallets + UAT) fits within 4,500 to 7,000 EUR and ships in 2 to 3 weeks. A project with ERP reconciliation and fine-grained dispute handling climbs toward 10,000 to 15,000 EUR over 4 to 5 weeks.
PSP comparison: commission and total cost
The classic finance trap is comparing headline rates without projecting real cost over volume. Here are 2026 European grids (EU cards, estimate) and simulated monthly cost.
| PSP | EU card commission | Fixed fees | Cost / 1,000 transactions at 60 EUR |
|---|---|---|---|
| Stripe | 1.5 % + 0.25 EUR | 0 EUR/month | 1,150 EUR |
| Mollie | 1.8 % + 0.25 EUR | 0 EUR/month | 1,330 EUR |
| PayPal (checkout) | 2.9 % + 0.35 EUR | 0 EUR/month | 2,090 EUR |
| Adyen (volume) | 1.4 % + 0.11 EUR interchange++ | per contract | ~950 EUR |
| PSP + high-volume deal | 1.2 - 1.4 % | monthly fee | 850 - 950 EUR |
Read for a finance director: at 1,000 transactions/month of 60 EUR (60,000 EUR revenue), the PayPal vs Stripe gap reaches ~940 EUR/month, i.e. 11,000 EUR/year. That dwarfs the integration cost difference between two vendors.
Mini case study
Claire, finance director of a furniture SME in London, takes 55,000 EUR/month across 900 orders (average basket 61 EUR). She uses legacy PayPal at 2.9 % + 0.35 EUR, roughly 1,910 EUR/month in commissions. Migrating to Stripe (1.5 % + 0.25 EUR), her commission drops to about 1,050 EUR/month, a saving of 860 EUR/month, i.e. 10,320 EUR/year. Stripe integration plus reconciliation costs her 7,500 EUR: payback lands in under 9 months, then it is recurring net margin.
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FAQ
How much does online payment integration cost in London in 2026?
Expect 3,000 to 6,000 EUR for a standard PSP hookup, and 10,000 to 15,000 EUR with ERP reconciliation and advanced dispute handling. Timeline runs 2 to 5 weeks depending on scope.
What is the commission difference between Stripe, Mollie and PayPal?
In 2026, Stripe sits around 1.5 % + 0.25 EUR, Mollie 1.8 % + 0.25 EUR and PayPal 2.9 % + 0.35 EUR on EU cards. On 60,000 EUR monthly revenue, the PayPal/Stripe gap exceeds 900 EUR per month.
Is 3-D Secure 2 mandatory?
Yes, strong customer authentication (SCA) applies to most payments. Good configuration exempts low-risk transactions to limit friction without losing compliance.
Can PSP rates be negotiated?
Yes, from around 50,000 EUR monthly revenue. An interchange++ grid or a volume contract pushes the effective rate below 1.4 %, which often justifies a flow audit.
How long to go live?
A Starter project is live in 2 to 3 weeks; a project with accounting reconciliation and multi-currency needs 4 to 5 weeks including UAT.
Let's scope your project. Share your monthly volume, average basket and current PSP: we cost the integration and the commission saving on the table. Detailed quote within 48 h. WhatsApp +221 77 596 93 33.
Mohamed Bah
Fondateur, Kolonell
Passionate about digital and entrepreneurship in Africa, Mohamed has been helping Sénégalese businesses with their digital transformation since 2020. Founder of Kolonell, he believes every SME deserves a professional and accessible online présence.
