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Legacy · Migration Engineering

Migrate legacy systems without freezing your business.

Strangler Fig pattern. Slice by slice. Wrap your legacy app behind a router. Cut each module to modern stack one at a time. Old + new coexist until done. Zero downtime. Zero feature freeze. Your team keeps shipping while we migrate underneath.

  • Strangler Fig pattern · slice-by-slice cutover
  • Old + new run side-by-side · canary rollouts
  • Data layer preserved · audit trails retained end-to-end
  • You own the code, day one - repo + infra access
Send your stack - we'll send a plan 15 min, no SDR
Strangler routing · live cutover
62%
Traffic on new
38%
Still legacy
0
Downtime
-41%
p95 latency
/a
/auth/*100% → new stack · canary done
Done
/r
/reports/*50% → new · ramping
Canary
/L
/ledger/*0% → still on legacy
Why Strangler Fig

Big-bang migrations are how businesses die.

No 18-month rewrites

Big rewrites take 2x longer than promised, ship 50% of original feature set, miss every business window. We don't do those.

Routing-layer cutover

API gateway / nginx / Envoy routes some endpoints to new stack, rest to legacy. Switch one slice at a time. Roll back in seconds.

Your roadmap stays live

Your team keeps shipping features on the legacy app. We migrate underneath. Business never pauses. No "code freeze for 6 months."

Six migration plays we run

From mainframe to modern, safely.

.NET WebForms → React

Server-rendered pages wrapped, each page migrated to React + Node API. SQL Server retained.

PHP monolith → Node

NestJS or Express services replace PHP endpoints route-by-route. Sessions migrated to Redis. MySQL kept.

Java EE → Spring Boot 3

EJB → Spring beans. JSF → React. WebSphere → embedded Tomcat. Module by module.

Mainframe / COBOL exits

Wrap COBOL with REST gateway. Rewrite calculations into Python / Java. Phase out 1 batch job at a time.

On-prem → AWS / GCP

Lift-and-shift first (EC2 / IaaS), then refactor (managed RDS, S3, Lambda, IAM). Hybrid mode during cutover.

Oracle → Postgres

Schema converted with pgloader / ora2pg. Stored procs rewritten in PL/pgSQL. Dual-writes during cutover for safety.

The cutover playbook

What "slice-by-slice" actually means.

Every slice is a real, full cycle - not a stub. By the end of the slice, that piece of functionality runs entirely on the new stack with the old stack as fallback.

  • Identify bounded context (auth, reporting, ledger, etc.)
  • Build new implementation behind feature flag
  • Shadow production traffic to new stack (read-only)
  • Canary cutover: 5% → 25% → 50% → 100% over 1-2 weeks
  • Legacy stays warm 2-4 weeks · then decommissioned
Cutover: /reports/* · canary 50%
N
New stack p95340ms · within SLO
Good
L
Legacy p95820ms · for comparison
⚠
Rollback readySingle LB flip · 30 sec
FAQ

Things teams ask before signing.

How long does a full migration take?
3-12 months depending on system size. We scope each slice in 2-week chunks. You see migration completing visibly every month. Most engagements show 50%+ traffic on new stack within 3 months.
What does it cost?
From $999 for a small migration. $5,000–$25,000 for full monolith re-platforming. Fixed-bid per slice. We quote each slice separately so you can pause / continue at any boundary.
What if a slice fails canary?
LB flips back to legacy in 30 seconds. We diagnose, fix, re-canary. Net impact: zero user-visible failure. This is the whole point of slice-by-slice + canary.
Audit trails?
Preserved end-to-end. Activity logs continue uninterrupted across cutover. RBI / SEBI / IRDAI / GDPR / DPDP compliant. We've shipped for regulated entities.
Send us your stack

Tell us what's legacy. We'll send a real plan.

BFSI, EdTech, manufacturing teams in India + Romania have migrated legacy with us - zero downtime. Send your current architecture - we'll come back with a slice-by-slice plan and a fixed quote per slice.

Send your briefTalk to an engineer · 15 min