APP Modernization

Legacy System Modernization: Refactor, Migrate and Connect Old Software, No Full Rewrite

As a Dhaka-based company, we deliver legacy software modernization services that help you fix the software your business runs on, one module at a time. We audit it, put it under test, refactor or migrate it to your cloud and switch it over with a rollback, for international companies, at a fixed price per step. The code was written years ago: every change is slow, every upgrade is a risk, and the rewrite quote frightened everyone. Our engineers and a quality assurance (QA) lead write tests around what your software does today before they change a line of it.

Stop after any step; nothing commits you to the next module. We start with the one module that costs you the most today: the one every change touches, the one nobody dares deploy, the one on the framework that lost support. Its code, dependencies, data and risks are mapped, the smallest safe change is defined, and every route to it is priced against your own numbers.

You get a written verdict — tests first, a framework upgrade and refactor, a move to your cloud, a module replaced beside the old one, or leave it alone for now. If nothing justifies a change, you stop here and keep the audit.

30 minutes 01 Scope · free call
2 weeks 02 Diagnose · $1,500 code audit, half credited
6–8 weeks 03 Pilot · $4,000, one module live
Per module 04 Production · from $6,000 per module
Monthly 05 Managed Ops · optional upkeep, cancel any time

What is included in legacy software modernization services?

Legacy software modernization services cover six pieces of work that bring the custom software your business still depends on to a supported, testable state: an audit that maps code, dependencies and risk, tests around today’s behaviour, refactoring and framework upgrades, migration to your cloud, an application programming interface (API) layer, and documentation your team keeps.

Code audit and modernization map

Every module, dependency, framework version, database and integration is mapped. A risk register and a module order say what to touch first and what to leave alone.

Tests around existing behaviour

Characterization tests are written around each module before it changes. Parity can then be proven after refactoring, and regression tests catch a break before a customer does.

Refactoring and framework upgrades

Unsupported language and framework versions move to supported ones. Dead code goes, dependencies are replaced and structure is cleaned, one module at a time and always behind the tests.

Cloud migration

Software moves off ageing servers into your cloud accounts, with backups, monitoring, access control and a deployment pipeline. It is re-platformed first and refactored where the audit says it pays.

API layer over legacy data

A documented, versioned API sits in front of the old system. Your customer relationship management (CRM) system, shop, portal or reporting tool then reads and writes its data without touching its code.

Database migration and handover

Schemas and data move to a supported database with a verified cut-over and rollback. Documentation, a runbook and optional monthly upkeep follow as the platform changes.

Not included: Mainframe and midrange systems · new front ends, which belong to web application development · new modules outside the agreed plan, priced first as a change request.

Which legacy software modernization path fits: refactor, re-platform, rehost or replace a module?

Legacy software modernization follows one of four paths, and the audit chooses by cost and risk. Rehost moves the system as it is; re-platform moves it onto managed cloud services; refactor changes the code, not what it does; replacing a module rebuilds one piece beside the old one. All four are application modernization inside our custom software development work.

Microsoft’s Azure Architecture Center states that the Strangler Fig pattern is used to “incrementally migrate a legacy system by gradually replacing specific pieces of functionality with new applications and services”, which is our replace-a-module path.

Rehost

The system moved to your cloud as it is, with backups and monitoring, when the code is sound, but the server is not.

Re-platform

Moved onto managed databases, storage and runtimes, so upgrades and scaling stop being your team’s weekend work.

Refactor

The code changed for supportability (framework, dependencies, structure) while every test proves the behaviour did not change.

Replace a module

One piece rebuilt beside the old system, traffic moved gradually, the old path retired once nobody uses it: the strangler pattern.

How does a legacy software modernization pilot switch one module over safely?

A legacy software modernization pilot switches one module over in five logged steps: scope signed, a safety net of tests, the refactor, a parity sign-off and the switch-over. The example is an invoicing module on an unsupported framework; every item traces to a test, a commit and a switch-over record, and yellow marks where a person signs.

Sample pilot log · invoicing module, unsupported framework

Pilot log · invoicing module

The module at that step · its result

Scope signed

Agreed before any code changes.

Scope itemSample module
ModuleInvoicing
FrameworkUnsupported
Endpoints38
Existing tests0
RollbackPlan agreed
38
Endpoints in scope0 existing tests · rollback plan agreed

Safety net

Tests pin down what the old code does today.

Old path112 tests green
New pathnot built yet
112
Characterization tests green on the old codewritten before a line is refactored

Refactor

The code changes; the behaviour must not.

Framework upgraded14 dependencies replaced
Old pathlive, unchanged
New pathrefactored · 112 tests green
14
Dependencies replaced112 tests still green

Parity sign-off · a person signs

Both paths run the same invoices.

Old patha week of invoices
New paththe same invoices
Differences0 · signed by 7 users
0
Differences between the two paths7 users ran a week of invoices on both

Switched over

The new module goes live beside the old path.

Old pathSwitch-overNew module live
Old path kept 30 days30 days of fixes
30
Days the old path staysretired only on your instruction

Pick a step, or a number below, to see the module at that stage

Each further module follows the same five steps, one at a time, while the old system keeps running.

Illustrative example. Yellow shows where a person signs; each entry is backed by a test, a commit and a switch-over record.

How do legacy software modernization services work, from scope to Managed Ops?

Legacy software modernization services come in five steps, each a place to stop, because modernization fails when it is sold as one big project: a free call, a two-week diagnostic that picks the first module, a six-to-eight-week pilot that puts that module live, production one module at a time, then Managed Ops. Every step ends with a written result.

01 30 min · free
Scope We talk through the module that hurts most, the stack it runs on and who still understands it. If the codebase and its users are known, the call ends with a diagnostic quote.
02 2 weeks · credited
Diagnose Code, dependencies, database and integrations audited; framework support dates checked; risk register written; the first module chosen by cost of change; the pilot priced in writing.
03 6–8 weeks · fixed price
Pilot Tests written around the first module, then refactoring or migration, deployment to your cloud beside the old path, parity proven, switch-over with rollback, and a demo every two weeks.
04 Per module · quoted after pilot
Production The remaining modules in the audit’s order, each with its own tests, switch-over and 30 days of fixes, plus documentation, a runbook and training for your team.
05 Monthly · optional
Managed Ops Dependency and security updates, monitoring, small changes and a monthly review of the risk register, with a named engineer who knows the code. Cancel any month; everything stays yours.

Who modernizes your legacy software, and with what?

Engineers who have upgraded old frameworks, a QA lead who owns the characterization tests and parity sign-off, and a project manager who runs the demos.

Communication A demo every two weeks in a shared Slack or Microsoft Teams channel

Delivery Your repositories, continuous integration pipeline, staging and production

QA Characterization tests, parity runs and user acceptance testing before every switch-over

Switch-over Every module beside the old path, with a written rollback

Cloud Backups, monitoring and access control in your cloud accounts

Ownership Code, tests, infrastructure and documentation, all in your name

Which legacy modernization step comes first: tests, a refactor, a cloud move, a new module or the audit?

The first legacy modernization step depends on five facts; five questions show which fits. Untested code needs the safety net first; an unsupported framework, an upgrade and refactor; a server in a cupboard, your cloud first; weekly changes by hundreds of users, a replaced module; a supported, tested system, an audit ranking. A new front end is web application development.

1. How often does the code still change?

2. Where does it run today?

3. Do automated tests exist?

4. Is the language or framework still supported?

5. How many people depend on it daily?

Which one do you need? Answer five questions.

A safety net first: tests around what exists

Nothing can be changed safely until the current behaviour is pinned down: characterization tests are written around the first module before a line is refactored, so parity can be proven at every step.

Book a Diagnostic

A first estimate; the diagnostic confirms it.

How the verdict is decided

No tests → the safety net first
End-of-life framework → upgrade and refactor
On a server in the office → your cloud first
Weekly changes and over 200 users → replace that module
Everything else → the diagnostic decides the order

Why choose us as your legacy software modernization company?

A legacy software modernization company is judged on whether the system is still running the day after switch-over, not on its slide deck. We deliver software modernization services under tests, module by module, priced in writing, with personal data in test copies handled under Article 28 of the General Data Protection Regulation (GDPR).

Without a staged process

!!!!!
  • A big-bang rewrite that is eighteen months late and still missing features
  • Changes made with no tests, found by customers on Monday
  • Hourly billing that grows every time the old code surprises someone
  • A new system in the vendor’s account you cannot run without them

With EICRA

Pilot report · Invoicing module
Endpoints38Tests written112Dependencies replaced14Parity differences0VerdictSwitched over
Illustrative example
  • Tests around today’s behaviour before a single line changes
  • A fixed price per step, with production quoted in writing after the pilot
  • Code, tests and infrastructure in your accounts from the first commit
  • Your sign-off on parity before any module is switched over

Is it safe to outsource legacy software modernization?

Outsourcing legacy software modernization is safe when tests, access and ownership are settled in writing, because the danger in old software is untested change. As a Bangladesh-based company, our engineers work in your repositories and cloud, change nothing without green tests, use masked data outside production, sign a data processing agreement and leave at handover. Reviewed By Eicra.com team

Every change also follows the National Institute of Standards and Technology (NIST) Secure Software Development Framework, whose practices “should help software producers reduce the number of vulnerabilities in released software”.

Which modernization agreements are signed, and when?

Non-disclosure agreement (NDA) — mutual, and signed before we see any code, credential or data sample.
Data processing agreement (DPA) — the processor terms of Article 28(3) of the GDPR, or your national equivalent, cover any personal data in the system and its test copies.
International data transfers — before personal data leaves your systems, we sign standard contractual clauses or whatever instrument your jurisdiction requires.
Access — each engineer gets a least-privilege role in your repositories and cloud; production credentials never leave your vault.
Certifications — we list a certification only when we hold it, and this page claims none.

What modernization controls, ownership and rework terms apply?

Your accounts Repositories, pipelines, environments and domains live in your accounts, or move there; we host nothing.
Code ownership The contract assigns all intellectual property (IP) to you, tests included; every third-party licence is listed, and no copyleft code enters without your sign-off.
Production data Test and staging environments run on masked or synthetic data; production is touched only through your access controls, logged, and never copied out.
Switch-over Every module goes live beside the old path with a written rollback; the old path stays for 30 days and is retired only on your instruction.
Rework Free of charge when a module fails its agreed parity tests; any new module is priced first as a change request.

What proof do you get before you pay for legacy software modernization?

Before you pay for legacy software modernization, you get evidence instead of promises: measured commitments, your own written risk register after the diagnostic, and a pilot that puts one module live before production is quoted. Named client results will appear here as clients agree to publication.

2 weeks

For the diagnostic: code, dependencies and risks audited, and a written plan that picks the first module.

6–8 weeks

From the start of the pilot to the first module live in your cloud, proven against tests.

30 days

The old path stays beside the new module after switch-over, with 30 days of fixes.

Case studies: modernization results with client names are published once each client agrees. On the scoping call, ask for references from your sector.

What do buyers ask about legacy software modernization?

How much do legacy software modernization services cost?

Legacy software modernization services here are priced by outcome, never by the hour, and every figure sits on the price cards at the top. A two-week diagnostic audits the code, maps dependencies and risks and ends in a written plan, half credited to the pilot. A pilot then puts one module live, and production follows.

What are legacy software modernization services?

Legacy software modernization services take the custom software your business still depends on (old frameworks, unsupported languages, a database nobody dares touch) and bring it to a supported, testable, cloud-ready state without stopping the business: a code audit, tests around the existing behaviour, refactoring or framework upgrades, migration to your cloud, an API layer, and documentation your team keeps.

Refactor or rewrite: which is cheaper and safer?

A rewrite looks cleaner on a slide and fails more often in practice: the old system encodes years of business rules nobody wrote down, and a rewrite must rediscover them all before it is useful. Refactoring module by module keeps the system running and spends money only where it hurts. We rewrite a module only when the audit proves it.

How long does legacy modernization take?

The first module is live in eight to ten weeks: a two-week diagnostic that audits the code, writes tests around current behaviour and picks the first module, then a six-to-eight-week pilot that refactors or migrates it, proves parity against those tests and switches it over. Further modules follow one at a time, so the system improves while it keeps running.

Can you modernize without downtime?

We plan for it and cannot guarantee it. Each module is modernized beside the old one, switched over with a rollback path, and switched back if anything fails; cutovers happen in your quiet hours with your sign-off. That keeps planned downtime to minutes per module in most cases; the diagnostic’s risk register says where it cannot be avoided.

Start with a free 30-minute scoping call or the two-week diagnostic.