Custom banking software development in Java, with a ballpark estimate
Ledgers, product engines, integration layers and the operational systems around a bank's core, for banks and banking-as-a-service providers. Built by the engineers behind an in-memory ledger at a billion transactions an hour, and sold as time and materials phases with a ballpark estimate, a retainer or a team.
- 1,000,000,000
- financial transactions in under an hour on an in-memory ledgerFastPost, developed for Legerity from 2013
- Sub-second
- queries over billions of balancesFastPost production figure
- Nearly 10 years
- our engagement with Legerity, from 2013Nathan Pesin, CTO, Legerity Financials
- Who it is for
- Banks with a Java system around the core that has become the constraint; banking-as-a-service and embedded finance providers building a platform; fintechs graduating to a banking licence
- What we build
- General and sub-ledgers, product and pricing engines, payment hubs and integration layers, onboarding and KYC orchestration, reporting and reconciliation, operations portals
- How it is sold
- Application Modernization Sprints for the systems you run today, time and materials builds with a written ballpark for new components, Managed Support to run them, Team Extension when you own the roadmap
- Constraints we work to
- Your change management, your access controls, DORA third-party evidence, and a parallel run before any cutover that touches money
What banks want from the systems around the core
Ship products without a core release
Deposit, lending and fee products defined as configuration and launched while the core stays as it is.
Retire the core one module at a time
New channels and products on the new side of a strangler seam, the old core shrinking over years rather than in one cutover.
Pass third-party risk review quickly
A short supplier chain, EU-based engineers, your access controls and a documented exit plan.
One ledger every report agrees with
Regulatory and management figures drawn from a single versioned ledger.
Around the core, and sometimes the core itself
Ledgers
General and sub-ledgers as versioned facts with sub-second balance queries, in-memory where the volume demands it. FastPost, developed for Legerity, is the reference.
Product and pricing engines
Deposit, lending and fee products defined as configuration, priced by rules you can read, launched without a release.
Payment hubs
Instant, batch and card rails behind one integration layer, with idempotency and reconciliation designed in.
Integration layers
The strangler seam around a legacy core: the layer that lets new channels and products ship while the core stays where it is.
Onboarding and KYC orchestration
Workflow across identity, screening and document providers, with the decision trail regulators ask for.
Reporting and reconciliation
Regulatory and management reporting that reconciles to the ledger because the ledger is the only source.
Banking-grade systems we built
- Flagship · Banking and fintech · from 2013
FastPost: a billion financial transactions in under an hour
FastPost, a rule-driven, high-performance accounting platform developed for Legerity by Stratoflow from 2013, used by telcos and insurers worldwide.
1,000,000,000 transactions / hour
- Ecommerce · Banking and fintech
Mennica Skarbowa: real-time pricing engine for an omnichannel precious-metals platform
Intraday base prices from London Metal Exchange and distributor feeds, a rules-driven margin engine, and price distribution to web stores and physical shops.
Intraday repricing, every channel
The bespoke metal exchange platform works great, it is easily accessible and richly functional. Stratoflow managed deadlines capably, meticulously documented their progress, and delivered a complex project at an affordable cost.
Bartłomiej KnichnickiVice Chairman, Supervisory Board, Mennica SkarbowaServices for banking systems
Custom banking software, the practical questions
Do you replace core banking systems?
Rarely all at once, and we will argue against it. The pattern that works is a strangler seam around the core, new products and channels on the new side, and the core retired module by module over years. We have done that in scoped phases; the first phase sets the ballpark for the rest.
How do you meet a bank's third-party risk requirements?
Direct employees only, EU based, your access controls and change management, DORA-style incident and continuity evidence, and a documented exit plan in every contract.
How much does custom banking software cost?
A written ballpark per component or module set after the scoping call, a monthly retainer for support, or a monthly team fee. Every number is given in writing, and the first delivery phase shows in working software what the rest is likely to take.
Will the bank own what you build?
Yes. The code sits in repositories you control from day one, the agreement assigns ownership to you, and handover with documentation is part of the scope.
How big is the team behind it?
A boutique team of senior engineers, every one a direct employee. In a bank's third-party review that means a short supplier chain and a named team rather than a staffing pool.
What technology sits behind a custom banking system?
Java and Spring for the services, an in-memory data grid where balance queries have to stay sub-second, Kafka for events between the core and new channels, and PostgreSQL as the relational store.
Around banking
Book a scoping call
Thirty minutes with an architect, not a salesperson. You leave with a written view of scope, price model and whether we are the right team for it.