Blueprint · 09 Bank switch

Migrate off a legacy core without going dark.

Reference architecture for an existing bank moving off a legacy core, or an SME switching primary banking relationship. Klyqo runs a parallel runtime above both cores, gradually shifts journeys, migrates standing orders + direct debits + balance, zero-downtime cutover. Built for institutions that can’t take a weekend offline.

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The use case

The hardest banking project: change the engine while flying.

Core migration is the most expensive, highest-risk project a bank ever runs. Most attempts go over budget or get reversed. The reason is that incumbents treat it as a big-bang — weekend cutover, hold your breath, hope. Klyqo’s shape supports the opposite: parallel run, journey-by-journey migration, gradual ownership shift.

Zero downtime
Cutover target
Journey-by-journey
Migration cadence
4–12 months
Typical project window
Parallel run
Old + new simultaneously
The architecture

Two cores. One runtime. Gradual ownership shift.

Klyqo sits above both the legacy core and the target core during the migration window. Journeys read + write to one or both depending on configuration. The migration is journey-by-journey: KYC first, accounts next, payments after, until every journey runs against the target. The legacy core dims gradually instead of being switched off.

Compliance railRegulator notified per jurisdictional rules; per-journey audit retained
Layer 5 · Channels
Customer-facing surfaces (unchanged during migration)
Mobile appWeb bankingBranch toolingOperator console
Risk railData-integrity reconciliation between cores; rollback path per journey
CompliancePer-journey signed audit; reconciliation logs available to regulator
Layer 4 · Klyqo · the Banking OS
Runtime + dual-core dispatch
ComposeDispatch (dual)RunObserveReconcileCutover (per-journey)
RiskDaily reconciliation between cores; alert on discrepancy
ComplianceMigration tooling certified for the jurisdiction; data-residency preserved
Layer 3 · Marketplace primitives & providers
Provider stack (unchanged during migration)
Existing providers retainedBindings unchangedAdapter behavior preserved
RiskProvider-level changes deferred during migration window
ComplianceBoth cores audited concurrently; reconciliation reports daily
Layer 2 · Core banking
Legacy core ↔ target core
Legacy core (dimming)Target core (Mambu / equivalent)Per-journey ownershipReconciliation
RiskPer-journey ownership documented; rollback plan tested before cutover
ComplianceExisting banking licence; migration regulatory engagement
Layer 1 · Foundation (yours)
Licence (unchanged) · sponsor · project cover
Banking licenceMigration sponsorshipRegulator engagement
RiskProject sponsorship + executive cover for the migration window
The canonical journey

Each journey migrates on its own schedule.

Migration runs as a per-journey project. KYC migrates first (low risk, high learning). Accounts next (medium risk). Payments after (highest risk, last). Each journey’s migration window is a few weeks of parallel run plus a per-journey cutover. The customer sees nothing change.

klyqo / journeys / core-migration · LIVE
01
Both cores connected to Klyqoadapters wired; journeys still on legacy
weeks 1–2
02
KYC journey shiftedfirst migration · lowest risk · full reconciliation
weeks 3–6
03
Account-opening shiftedaccounts created in target; legacy read-only mirror
weeks 7–10
04
Payments shiftedhighest risk; most thorough reconciliation; gradual ramp
weeks 11–18
05
Standing orders + DDs migratedscheduled re-anchoring; customer notified
weeks 19–22
06
Balance migrationper-account cutover; final reconciliation
weeks 23–26
07
Legacy core retiredread-only archive for regulator; target is primary
week 27+
The providers used

What you pick from the marketplace.

A bank-switch project mostly preserves the existing provider stack. The marketplace work is the adapter to the new core and the reconciliation tooling.

Target core
Mambu (or modern equivalent)
The core you’re migrating to. Klyqo wires the adapter; configuration mirrors your product catalogue.
In flight
Legacy core adapter
(custom)
Klyqo builds a read/write adapter to your existing core for the migration window. Decommissioned at end.
Roadmap
Reconciliation tooling
Klyqo-native
Daily reconciliation per journey + per account between cores. Discrepancy alerting.
Roadmap
Existing providers
Retained
KYC, AML, cards, notify — all retained during migration. Provider changes deferred to post-migration.
N/A
Regulator-export bundler
Klyqo-native
Migration reports + reconciliation logs exportable to regulator on demand.
Roadmap
LLM-as-binding
Anthropic / OpenAI
Operator Copilot helps triage reconciliation discrepancies + draft migration status reports.
Roadmap
What this blueprint is and isn’t

Honest about the build.

The work this blueprint represents

Core migration projects fail more often than they succeed. The failures aren’t about technology — they’re about scope creep, executive impatience for a big-bang cutover, and reconciliation discipline that erodes over a 12-month window. Klyqo’s shape encourages the opposite: small migration units (per-journey), continuous reconciliation, no big-bang. The discipline still has to come from your team.

What you bring: the existing banking licence, the legacy core access, the project sponsorship, the operations team. What Klyqo brings: the parallel-run runtime, the adapter to the legacy core, the journey migration cadence, the reconciliation tooling, the audit trail per journey. What we figure out together: which journey first (almost always KYC or onboarding), what the cutover criteria look like per journey, what the regulator engagement cadence is.

If you’re a bank planning a core migration and you don’t want to learn the big-bang lesson the way most banks before you did: talk to us before you sign with a tier-1 integrator who’ll quote you 18 months and a weekend cutover.

Considering a core migration?

If you’re a bank planning to leave a legacy core and you want a parallel-run, journey-by-journey migration shape instead of a big-bang, the first conversation is short. Tell us about the legacy core, the target, the timeline, the executive sponsorship. We’ll tell you honestly what a 6 to 12 month Klyqo-shaped migration looks like.

Email diogo@klyqo.com Response within two business days