Legacy application migration: 6-Step Guide

a man and a woman carrying a cardboard box

Business digital transformation and the need for sustainability, ever-growing data volumes, and increasing computer and network speeds are only growing. Companies are refusing legacy systems and migrating to the cloud to ensure business continuity, avoid risks associated with the use of outdated systems and obstacles to business modernization.

More often, executive teams realize the importance of legacy app modernization to improve business processes, deliver enhanced customer experiences, and reduce operating expenses.

We have figured out why moving away from legacy systems is now so important for the successful business functioning, described potential risks and challenges of migrating to the cloud, and prepared a 6-step guide to perform it seamlessly and successfully.

Why are migration and modernization so important?

Legacy not only means the age of software or its tech stack. Due to the lack of support or its inability to meet the needs of a business, the system is considered legacy. Gartner defines legacy systems as "information systems that may be based on outdated technologies, but are critical to day-to-day operations". We had an experience of such system modernization, namely, transferring a core app from flex / flash to HTML5 for a large telecommunication company.

To stay competitive today, small to midsize businesses focus on cloud adoption and usage of cloud computing services such as IaaS, PaaS and SaaS. Year over year, such spending on cloud has grown substantially.

According to the Flexera 2022 State of the Cloud Report, 53% of SMBs are now spending $1.2 million annually on the cloud—up from 38% in 2021.
Top cloud initiatives for 2022 across all organizations
Source: Flexera

Legacy system migration to the cloud represents a transfer of some or all of the data center capabilities into the cloud, usually to run on the cloud-based infrastructure provided by a cloud service provider such as AWS, Google Cloud, or Azure.

Benefits of migration to the cloud

Cost reduction.

There's no need to purchase expensive server equipment and all the time to pay for its maintenance. You also cut operational expenses as your specialists and system administrators don’t need to spend time on backups and hardware maintenance. Companies pay only for the cloud resources that they use and cloud providers assume maintenance and upgrades.


To quickly respond to peak demands or when there is a need for more powerful resources, companies can automatically increase their cloud capacity on demand. It's not a must purchase additional equipment and install it to increase the capacity of the on-premises software.


Reliable cloud providers regularly upgrade their services following the latest industry standards and complying with regulations to reduce the risk of cyberattacks


As not all cloud deployments go smoothly, some problems with hardware and downtime might occur. However, most cloud vendors have service-level agreements that guarantee 99% uptime. In addition, vendors handle backups and disaster recovery, which can save your team a lot of time.

Challenges of legacy system migration

Migrating large numbers of workloads from an on-premises data center and infrastructure to the cloud requires careful planning. Here are some features need to be borne in mind:

Cloud compatibility.

Some legacy applications may be incompatible with a cloud environment. And companies require either re-architecture or re-factor their existing apps to make them compatible with the cloud environments. Such a process can be rather time-consuming and expensive for large systems, and the decision to migrate depends on the type of application and its impact on the business capabilities.

Customization and adoption.

Cloud migration brings a lot of change and can disrupt everyday work and likewise lead to short-term losses in productivity. To avoid this issue altogether by identifying which parts of software depend on one another before moving any data and then transfer these groups together.

Skill shortage.

Companies may run into a lack of talent for cloud migration. This will lead to the need to find a reliable service provider with proven expertise in app migration and a strong team for its implementation.

Financial cost.

Upgrading can sometimes exceed the business value in the short run and cause some companies to stick with what they have. However, it's true that modernization ends up in bringing business value by increasing scalability, reliability and cutting operating costs in the future.


Many migrations fail, the cost goes above budget and the migration takes much longer than planned. This happens due to a lack of a thought-out plan and insufficient expertise in project evaluation. Companies should create a modernization roadmap with well-documented expectations and upgrade priorities based on the ongoing assessments of current technology stack and ability to undertake the migration.

Steps to successful legacy application migration

Cloud migration can pose a significant challenge, but recognizing potential risks and obstacles in the beginning, along with careful planning, helps you manage them. Here we describe the steps to successful application migration:

Step 1. Set goals and define a cloud migration strategy.

Planning a strategy helps to find out the best way to implement the cloud migration into your business. You should have a clear understanding why to migrate legacy systems, its applications or some component to the cloud. Determine and analyze business goals and objectives, and how your company can benefit from the cloud migration project. Think as well about performance, timeframe, and cost goals for understanding the concrete numbers to aim towards.

Step 2. Define components for migration.

It is important to assess your environment and determine the factors that will define the migration, such as critical application data, legacy data, and application compatibility. As we have mentioned, some app components are perfect for cloud migration, the others are not. You should identify which data needs to be migrated and when, and whether you need encryption of the data, which could be an additional challenge.

Step 3. Choose the right provider of cloud computing services.

The right tech stack contributes to building a reliable and efficient product and the choice of the best-suited cloud provider should be based on your business needs and product specifics. All cloud providers, AWS, Azure and Google Cloud, offer various cloud computing services required for any basic business. The difference occurs in a number of regions and availability zones where they are hosting, the number of services they are providing, their customer-friendly pricing models and discount models, as well as their integration with open-source and on-premise systems, such as MS tools.

Enterprise public cloud adoption rates
Source: Flexera
Step 4. Evaluate the company’s possibilities.

Once the business requirement has been determined, the relevant services offered by cloud providers and their costs understood, it's time to define the possibility of migration by its own workforce. Sometimes it's hard for companies to find the talent or upskill existing staff to manage the new technology and maximize its value. This can lead to additional unexpected costs and time delays to realize the full return on the modernization investment. And here a better solution would be to find an outsourced company with an expertise in legacy application migration.

Step 5. Implementing the migration.

The major challenge here is carrying out your migration with minimal disruption to normal operation, at the lowest cost, and over the shortest period. If your data becomes inaccessible to users during a migration, you risk affecting your business operations. You’ll also need to synchronize changes that are made to the source data while the migration is ongoing. AWS provider, for example, has such built-in tools during AWS cloud migration. Every workload element individually migrated should be proven to work in the new environment before another element migration.

Step 6. Evaluate migration success.

The final step of the process is to analyze whether your cloud system is working according to your expectations. Test for minimal downtime, data integrity, ensure that no data is lost, and check your applications are fully functional. In case of any difficulties or problems with the functionality, you can contact your cloud service provider to get the issue resolved as soon as possible.

Final thoughts

Cloud adoption enables keeping up with the present-day technologies, better management and protection of sensitive data. Despite the migration process being a complex, risky and time-consuming process, requiring significant investment in time, tools, and resources, the results are worthwhile for long-term success.

In case of inability to do it on their own, because of lack of experience or insufficient IT-department, companies should consider attracting an outsourced cloud migration partner to assist with the task. At Twelvedevs, we support you throughout the migration lifecycle, from your current system analysis to implementation and support.

Yulia Slauta
As a content writer, Yulia strives to provide relevant and useful information in an accessible way to help navigate complicated concepts and make right decisions