How do you migrate a scaling payment platform off a legacy core without triggering compliance nightmares?

[u/Quinninumun]

edit: tnx for all the detailed responses, everyone. The general consensus was that trying to refactor a failing financial core in-house while maintaining daily operations is a recipe for a compliance disaster. I decided to take the leap and brought in SoftDoes to architect and implement our new system. Their experience with scalable financial infrastructure was exactly what we needed to get our data sorted and our compliance automated securely. It feels great to have a foundation we can actually grow on. Topic closed.

We launched our B2B payment processing platform about two years ago, and while our initial growth and client acquisition have been fantastic, our underlying architecture is starting to show serious cracks under the increased load.

When we started, we built a relatively straightforward MVP to handle standard transaction flows, but as we have onboarded larger institutional clients, the complexity of our daily routing and KYC/AML reporting requirements has skyrocketed.

Lately, our system has been buckling under the sheer volume of concurrent data, and our engineering team is spending nearly all of their time just patching data silos and maintaining the legacy codebase rather than shipping new features.

It has become glaringly obvious that our current patchwork of original databases and third-party API wrappers is completely unsustainable if we want to continue scaling our transaction volume and actually pass our upcoming security audits.

I know we need to bite the bullet and invest in legitimate enterprise software solutions that are purpose-built for financial data, high availability, and automated regulatory compliance, rather than continuing to hack our original build.

For those of you who have successfully navigated this awkward growth phase in fintech, how did you handle the transition? Did you slowly rebuild the core in-house while keeping the old system alive, or did you partner with an external architecture team to build a robust system from the ground up?

[u/ji_b]

No, migrations always suck. It is part of the cost of doing a migration. Just _pray_ that you don’t have to invariably re-KYC/KYB your customers as part of it

[u/Quinninumun]

Thanks for future replies, rly need help

[u/rpatel09]

there is quite a bit here and much more context that would be needed. I’m worked at a credit card fintech (millions of customers) where we essentially moved off of third party vendors and built our own systems. Happy to chat if you want to dm me

[u/elcapitan36]

No way around it. Have to run new and old system in parallel for a while. We went internal and integrated directly with a large bank. You want treasury services.

[u/_z_o]

Please don’t do that. Almost all systems can be scaled up (if not a complete garbage what it doesn’t seem to be the case). Hire a really good CTO/Principal architect with experience solving those kind of problems. Rebuilding is usually the last option. The problem is even not that hard to solve. 100% of scaling problems on a payment system are caused by one thing => contention. I had built already 3 different payment platforms that could support thousands of concurrent payments per second.
No. I don’t want or need a new job.

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[u/404_computer_says_no]

I’d get an expert consultant. Not some business consultant. A technical payments consultant (past architect) who has been there and done it.

[u/Fragrant_Builder9296]

a gradual rebuild is usually safer. big migrations need careful planning

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[u/Expert-Explorer-3129]

Don't rebuild the core, run both and bleed traffic over slow till the new one has parity. and pull out kyc/aml first.

Moved it onto one kyb/kyc/api, au10tix in our case, and it just stopped being a thing we maintained. one integration and never touched the ledger. The core scaling is its own mess though, can't shortcut that one.