Online payment processing software · engineering partner
Online payment processing software,
engineered as a system you own.
TrustChange is a team of online payment processing software developers for EU-facing PSPs, EMIs, neobanks and licensed VASPs. We engineer the checkout, the tokenisation and vault, the router across rails, the risk and PSD2 controls, the ledger and the compliance evidence as bespoke software under your brand — not a SaaS licence with a per-transaction fee. You get online payment processing software your product team can extend, your ops team can run and your auditor can read.
- EU-based engineers
- PSD2-aware delivery
- PCI DSS scope kept small
- AML & sanctions in code
- GDPR-aware storage
What "online payment processing" means here
Online payment processing software without the SaaS strings
Most searches for online payment processing software surface multi-tenant SaaS with a fixed feature set and a per-transaction fee, and the merchant relationship sits partly with the vendor. We work the other way. TrustChange is a bespoke online payment processing software partner: your brand, your rails, your vault, your merchants, your code. What you buy is engineering, not a subscription.
Deciding whether to buy, build or wrap what you have? Start with CTO advisory. The wider gateway view sits on payment gateway engineering, and the card-only angle on credit card payment processing software.
Product surface
Three surfaces in every online payment processing software developers engagement
An online payments stack is not one app. It is the merchant-facing checkout, the internal console your merchants and your ops team live in, and the APIs and SDKs your merchants build against. We ship all three as one product, on one architecture, with one team accountable end to end.
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01
Checkout & tokenisation
Hosted, embedded and in-app checkouts under your brand — card, SEPA, open banking, wallets and stablecoins — with PCI-scope-minimising tokenisation up front.
- Hosted + embedded
- Client-side tokenisation
- Apple Pay · Google Pay
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02
Merchant & ops console
The internal console your merchants and your ops team run the online payments from — transactions, refunds, chargebacks, disputes, payouts, allow-lists and cases.
- Role-based access
- Dispute & chargeback workflow
- Payout scheduler
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03
APIs, SDKs & webhooks
Server APIs, mobile SDKs and signed webhooks so merchants can build the online payment processing software into checkout, PoS or in-app flows without touching PCI-scope data.
- Signed REST + webhooks
- Native iOS + Android SDKs
- Sandbox environment
Stack
What sits behind bespoke online payment processing software
Eight layers, one system. Every layer names an owner, a control and a piece of audit evidence — nothing is left implied under the "online payments" label.
Delivery patterns and evidence: how we deliver. Wider platform view: fintech infrastructure. Fiat-to-crypto legs: on- and off-ramp integration.
| Layer | What we build |
|---|---|
| Product surface | Hosted checkout, merchant + ops console, mobile SDKs under your brand One product surface, no shared multi-tenant backend behind it. |
| Tokenisation & vault | Client-side tokenisation with a network-token-ready vault, hosted fields and 3-D Secure step-up Raw PANs stay out of your systems; PCI DSS scope stays small. |
| Payments router | Rule-based routing across acquirers, PSP partners, open-banking providers and stablecoin rails with failover New rails or providers plug into the same router without a code change. |
| Risk & fraud controls | Velocity, device-fingerprint, 3-D Secure exemptions and vendor score integrations before capture Rules run inside the flow; every decision writes to the audit log. |
| Compliance controls | PSD2-aware flows (SCA and exemptions), KYC/KYB, sanctions and Travel Rule where relevant Your compliance policy set by your team, the enforcement shipped in code. |
| Ledger & reconciliation | Double-entry ledger with idempotent postings and daily reconciliation against acquirer files Retries never mint money twice; every posting carries a source id. |
| Reporting & payouts | Merchant statements, payout scheduling, GL exports and auditor bundles Regulator-shaped exports out of the same store as merchant reports. |
| Runtime & delivery | EU-hosted, CI/CD pipelines, observability, 24/7 on-call cover Your identity provider, your key custody, your data regions. |
Payment path
From checkout to settled funds
Every online payment in the platform goes through the same gates before funds move. Speed comes from tuning the pipeline, not from skipping a step or trusting the caller.
- 01
Checkout
Real time
A shopper hits your hosted or embedded checkout; a token is created client-side and the PAN never touches your systems.
- 02
Risk
Sub-second
Velocity, device-fingerprint and vendor scores run before authorisation is requested.
- 03
SCA
As required
3-D Secure step-up is invoked or an exemption is claimed under PSD2 policy configured by your compliance team.
- 04
Route & auth
Sub-second
The router picks the acquirer with the best fit and requests authorisation; retries follow policy.
- 05
Capture
Immediate or delayed
Funds are captured; the ledger posts a double-entry with source id and rule version.
- 06
Settle & report
T+0 to T+1
Payouts land on schedule; merchant statements, GL exports and auditor bundles publish from the same store.
Delivery
How we deliver an online payment processing software project
Five steps, in this order. Regulated online payment work runs inside the product backlog — no separate compliance phase bolted on before launch, no big-bang release of an untested online payment processing software stack.
- 01
Scoping
Weeks 1–2
We map merchants, rails, provider mix, licence context and the risk you must stand behind. Output: a scope, a control map and a costed plan.
- 02
Architecture
Weeks 3–4
Router topology, vault design, ledger schema, PSD2 flow and merchant onboarding written down first. Regulatory constraints shape the design.
- 03
Build
Two-week sprints
Checkout, router, risk, admin and payouts ship in slices. Each merge runs tests, static checks and a dependency scan.
- 04
Hardening
Before launch
Load work, failure drills, replay against historical files and a third-party pen-test window. Cut-over is rehearsed with merchants, not assumed.
- 05
Launch and run
Cutover + ongoing
Named engineers on 24/7 cover. Runbooks, dashboards, merchant playbooks and the audit log are handed to your team on day one.
Engagement
Four ways to buy engineering from online payment processing software developers
Same engineers, same standard. Only the commercial shape changes.
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Fixed-scope build
A defined online payments stack at a fixed price and date. Best when rails and provider mix are settled.
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Dedicated team
A standing squad with a lead. Best for long roadmaps and new rails each quarter.
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Staff augmentation
Senior engineers inside your team. Best when you already own the plan and need payments depth.
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CTO advisory
Architecture and buy-vs-build review before you commit. Best at the design stage.
Questions
FAQ: online payment processing software
Six answers up front on scope, off-the-shelf trade-offs, rails and methods, PCI & PSD2, AML/GDPR and support. Bring the rest to the call.
What do online payment processing software developers at TrustChange actually build?
We engineer a bespoke, client-owned online payment processing software stack end to end: hosted and embedded checkouts, tokenisation and vault, the router across acquirers and providers, risk and PSD2 controls, the ledger and reconciliation, the merchant and ops console, and the reporting. It ships as source code in your repositories, with the IP assigned to you. There is no per-transaction fee, no shared multi-tenant backend and no vendor gate between you and your merchants.
How is your online payment processing software different from an off-the-shelf provider?
Off-the-shelf online payment processing software bundles a fixed feature set and a licence fee, and the merchant relationship sits partly with the vendor. TrustChange shapes the stack against your actual rails, provider mix, licence context and merchant model. A bespoke build takes longer up front, but you keep every line of code, every provider adapter and every control decision — and you avoid the roadmap lock-in that comes with a rented gateway.
Which rails, methods and merchant flows do you cover?
Card acquiring (Visa, Mastercard, Amex), SEPA and SEPA Instant, open-banking pay-ins under PSD2, wallets (Apple Pay, Google Pay) and stablecoin rails where relevant. Standard merchant flows include hosted and embedded checkout, one-click and network-token-ready recurring billing, refunds, partial captures, chargeback and dispute workflows, and scheduled payouts. New rails or providers plug into the same router without a code change to merchants.
How is PCI DSS scope kept small, and how are PSD2 and SCA handled?
Card data is tokenised client-side using hosted fields, and only tokens flow through your systems — raw PANs stay outside your PCI DSS boundary. PSD2 flows apply SCA with 3-D Secure step-up or claim an exemption per the policy your compliance team configures, and every decision is stored with the rule version that fired. TrustChange is an engineering partner, not a QSA — we ship the controls and the evidence; your assessor confirms the report on compliance.
How are AML, sanctions and GDPR engineered into the platform?
TrustChange is an engineering partner, not a law firm — your compliance team and MLRO set the policy, we ship the controls and the evidence. That means KYC/KYB in merchant onboarding, sanctions and screening rules that run inside the flow, Travel Rule messaging on any crypto legs, and GDPR-aware storage with data mapping and retention rules. Nothing about licences, opinions or supervisor approvals is claimed on your behalf.
Do you also run the online payment processing software after launch, or hand it over?
Both are on the table. Most clients start with named TrustChange engineers on 24/7 cover during the first months while their own team ramps up, then take the platform in-house with runbooks, dashboards, merchant playbooks and the audit log. Some keep us on as a dedicated development team or on staff augmentation for new-rail and control roadmap work, or as CTO advisory on architectural calls.
Book a discovery call with online payment processing software developers
Bring the rails, the target merchants, the licence context and the launch date. We come back with a control map, an architecture view and a costed plan for an online payment processing platform you own end to end. No demo theatre.