Payment and integration architecture for banks, payment companies, and regulated platforms
I design and repair the systems these teams run on: ISO 20022 and SWIFT messaging flows, MQ and event-driven integration layers, and the reconciliation and audit paths behind them.
Ten years across banking, telecom, and cloud platforms, four of them as a CTO and architecture lead. Client detail stays off this site, and the reason is further down the page.
Teams where an architecture mistake is expensive
I work with founders, CTOs, engineering leaders, and product teams building systems where reliability, auditability, integration, security, and delivery speed all matter at once.
Fintech and regulated products
Banks, payment processors, remittance products, lending platforms, and banking vendors. Correctness has to be auditable, failure is expensive, and the integration surface is usually the hardest part of the system.
Teams integrating with banks and payment rails
Product teams about to connect to a bank, a card scheme, a core banking platform, or a payment rail for the first time, who want the design reviewed before six months of engineering goes into it.
What teams call me about
- We're getting duplicate settlements and nobody can reproduce it
- Our integration layer has become the thing everyone is afraid to touch
- We're going into a bank integration and don't know what we don't know
- Reconciliation breaks at month-end and we fix it by hand every time
- An auditor wants proof of what happened to a specific transaction, and we can't produce it
- We're about to commit six months of engineering to a design nobody senior has reviewed
- Our AI pilot works, but we can't put it near regulated data as it stands
How I think about payment systems
Four positions I hold, so you can see where I stand before you pay me anything.
- 01
Exactly-once delivery doesn't exist. Design for idempotency instead.
A broker that advertises exactly-once semantics is describing a guarantee that holds inside its own boundary. It stops holding the moment your handler talks to a database, an external rail, or a second service. What works instead is making it harmless to process the same instruction twice. That is a design property rather than a configuration flag, and it has to be settled early, because retrofitting it means touching every consumer you have.
- 02
Reconciliation is a property of your message design, not a batch job you add later.
Teams routinely design the happy path first and treat reconciliation as reporting. Then month-end arrives, the numbers don't agree, and someone starts fixing them by hand. If your messages don't carry enough identity and causality to reconstruct a transaction's full history from either side of an integration, no downstream reconciliation process can recover what the design left out.
- 03
The integration boundary is where payment systems fail, not the core.
Core logic gets attention, review, and tests. The seams between systems get a mapping document and an assumption that the counterparty behaves. Almost every serious incident I have been called into started at a boundary: a field silently truncated in translation, an acknowledgment that never arrived, a partner whose retry behaviour nobody had measured under load.
- 04
An audit trail is a product requirement, not a logging concern.
Regulators, partner banks, and customers' lawyers all ask the same question: show exactly what happened to this transaction, and prove nothing else touched it. They usually ask at short notice. If the answer depends on correlating four log streams by timestamp, you don't have an audit trail. Building this in during design costs very little. Adding it afterwards is expensive.
How you can hire me
Payment & Integration Architecture Review
Two weeks · Fixed price $8,500
A structured teardown of your payment or integration layer, delivered as a written assessment with a prioritised remediation roadmap your team can carry out without me.
Things I go looking for:
- Message idempotency under MQ redelivery, and what happens when the same payment instruction arrives twice
- Reconciliation gaps when acknowledgments arrive out of order, or never arrive
- In-flight transaction handling during failover and deployment
- Poison messages and retry storms taking down a consumer under load
- Field-level data loss in ISO 20022 mapping, and where it surfaces months later in compliance reporting
- Audit trail completeness, and whether you can reconstruct the full history of a given transaction
- Places where exactly-once delivery is assumed in the design but not guaranteed by the infrastructure
You get a written assessment, an annotated architecture and data-flow map, a ranked risk register with business impact, and a remediation roadmap, plus a working session with your engineering team to go through it.
If at the end of the first week you don't think the review will be worth what you're paying, say so and we stop. You pay half and keep everything produced so far.
What the deliverable looks like
Every review produces the same document structure, typically 25 to 40 pages depending on system complexity:
- 01Executive summary: what I found, what it puts at risk, and what that would cost you
- 02System and data-flow map, annotated with message paths, boundaries, ownership, and where state actually lives
- 03Failure-mode analysis, giving each identified weakness a reproduction path, a blast radius, and a likelihood
- 04Ranked risk register, ordered by business impact rather than technical severity, with the two orderings compared where they differ
- 05Remediation roadmap, sequenced, with effort estimates and a note on what your team can do without me
- 06Open decisions, meaning the ones with no clean answer, set out with the tradeoffs stated plainly
The review closes with a recorded working session where your engineering team can take the findings apart.
Implementation Sprint
Three to four weeks · From $14,000
Scoped delivery against a defined outcome: an integration built, a messaging layer rebuilt, or an AI workflow moved into a regulated environment with audit logs, approval gates, and data boundaries intact.
Typical scopes:
- ISO 20022 or SWIFT messaging flow designed and implemented end to end
- Event-driven integration layer replacing brittle point-to-point connections
- Reconciliation and exception-handling design for a payment flow
- Retrieval and tool-use AI workflow with guardrails, human approval, and evaluation, deployed where regulated data lives
Fractional Architecture Partner
Ongoing · From $6,000/month
Senior architecture judgment on retainer, for founders and engineering leaders who need it continuously but can't justify a full-time hire. Roughly four to six days a month.
What that covers:
- Weekly architecture and design review sessions
- Decision support on vendors, platforms, and build versus buy
- Delivery oversight and technical risk escalation
- Direct support to your engineering leads
Most engagements start with the Architecture Review. It stands alone as a deliverable, and it is the fastest way for both of us to find out whether something longer makes sense. Email me and we'll scope it in a couple of messages.
Why there are no logos on this page
Most of my work has been inside banks, regulated platforms, and companies that do not want their architecture discussed publicly. I don't publish client names, logos, or case studies, and I won't reuse your material as marketing either. If you want to verify my background before we talk, my employment history is on LinkedIn.
What you get instead is the full outline of the deliverable above, and a first conversation specific enough that you can judge the work directly.
How engagements work
- 01
Email exchange
Tell me what the system is, what's going wrong, and what failure would cost. Two or three messages is usually enough to establish whether there's a fit and to scope a review.
- 02
Paid review or focused sprint
We start with a focused architecture review, prototype, or implementation sprint, scoped around a clear technical and business outcome.
- 03
Implementation or advisory
If there is a fit, I continue as an implementation partner, fractional architect, or delivery advisor.
Tools and platforms
Architecture matters more than tooling, but teams usually want to see the range behind it. I work across languages and stacks, and the list below is what I have shipped in production rather than a set of preferences.
- Enterprise & fintech
- ISO 20022-style messagingBPM / BAWTOGAFBABOKITILDomain-driven design
- Blockchain & distributed ledger
- Hyperledger FabricEthereumRipple / XRP LedgerChaincode & smart contractsPermissioned network designConsensus & finality models
- Backend & integration
- JavaJ2EENestJSNode.jsGraphQLRESTMQEvent-driven architecture
- Cloud & platform
- AzureKubernetesDockerHelmPulumiCI/CDObservability
- AI systems
- RAGLLM workflowsPrompt-injection awarenessEvaluationAudit logsGuardrailsHuman approval
- Data & identity
- PostgreSQLMySQLDB2RedisKeycloakOAuth / OIDC
- Product & mobile
- ReactReact NativeExpoProduct strategyUX-focused delivery
Before you email
- Why won't you tell me who you've worked with?
- Because the clients whose systems I've worked on didn't hire me to talk about them. Confidentiality is part of what you're buying, and a consultant who advertises the last engagement will advertise yours. My employment history is public on LinkedIn if you want to verify the background.
- Why fixed price rather than a day rate?
- Because a day rate makes it in my interest to take longer, and you shouldn't have to manage that. The scope is defined up front, the price doesn't move, and if the work runs long that is mine to absorb.
- Can you work alongside our existing team?
- That's the normal case. I'm not there to replace anyone's judgment. I review the design, name what's fragile, and hand your engineers something they can act on. Most of the value shows up in the working session, when your team pushes back.
- What if we need implementation help afterwards?
- The review stands alone and is written so your team can execute it without me. If you'd rather I stayed on, that's an Implementation Sprint or a Fractional engagement, and the review fee comes off the first invoice.
- Will you sign an NDA?
- Yes, before any system detail changes hands. Send yours, or I'll send a short mutual one.
- Where are you, and how do you work?
- Cairo, working UK and US-East overlapping hours. Reviews run remotely by default. I travel for onsite discovery when the system or the room makes it necessary.
Background
I'm Muhammad Salah Masoud, an architecture lead and former CTO working with teams across US and European timezones. I've spent 10 years building and leading cloud-native platforms, enterprise integrations, banking and payments systems, mobile products, and AI-driven workflows.
The work I'm best at is connecting product goals to the engineering constraints that decide whether they are achievable: reliability, security, integration complexity, cloud delivery, and the practical realities of shipping software inside a business.
Based in Cairo. I work UK and US-East overlapping hours, and travel for onsite discovery when an engagement calls for it.
Off the keyboard
I read a lot of technology and science, keep audio engineering and DSP going as a serious off-hours craft, and play more electric guitar than I probably should.
Get in touch
Email is the way in. I read everything and reply to anything with a real system behind it.
Worth including: what you're building, what's blocked or unreliable, what regulatory constraints you're under, and your timeline. A few rough sentences are more useful to me than a polished brief.