Skip to content
Sleek Lab000
Sleek Lab Solutions
All case studies
Financial Services2025Custom SoftwareCloudAPI Development

A payments core that clears in milliseconds

Replacing a decade-old payments engine with a real-time core processing millions of transactions a day, without a single minute of downtime during cutover.

Financial Services Platform
8ms

Median clearing time

3.4M

Daily transactions

0

Minutes of downtime

99.99%

Availability

The challenge

The client's payments engine was the bottleneck for every new product. Batch-based and brittle, it couldn't support instant settlement, and a full replacement had been declared 'too risky' twice before.

What we did

  1. 01Ran a two-week discovery to map every integration and failure mode of the legacy system.
  2. 02Designed an event-driven core with an immutable ledger and idempotent processing at its heart.
  3. 03Migrated traffic gradually behind a routing layer, proving correctness against the old system in parallel.
  4. 04Cut over region by region, with instant rollback available at every step.

They did in four months what two vendors couldn't in a year. The difference was judgment, they knew what to skip.

Get in touch

Let's engineer what's next.

Tell us where you're headed. We'll bring a small, senior team and a clear plan to get you there.