Making a legacy CRM ready for maintenance and further development

Financial operations depended on an undocumented CRM

A large company used a custom-built CRM for key financial operations and reporting. It had been developed more than five years earlier, and the original developer could not be found. The system ran without containers, had many dependencies, and lacked documentation. The IT team did not know how to restore it after a serious failure.

The concern went beyond the difficulty of making changes. A failure could have stopped part of the business for several days while the team tried to understand and restore an unfamiliar system under pressure. This was a potential risk, not an outage that had occurred.

The company did not want to invest heavily in a new CRM or a replacement for the existing one. The task was therefore to retain the system, understand how it worked, and prepare it for maintenance, recovery, and further development.

Investigating a copy and updating production

I restored a CRM backup in a local environment. This let me investigate the system and its dependencies without interfering with the production version employees continued to use.

I handled the investigation, containerization, and documentation independently. I documented the system, wrote maintenance procedures and recovery instructions, and prepared a foundation for future changes. Knowledge of the system no longer depended on the unavailable original developer.

A complete rewrite was unnecessary. Replacing the CRM would have meant rebuilding the functions employees already relied on. In this project, modernizing the existing system achieved the required result without developing a replacement.

The production transition required particular care because daily operations depended on CRM availability. I handled this stage jointly with the company's DevOps staff, who were responsible for the infrastructure. Together, we carefully managed the switch to the updated CRM.

A foundation for maintenance and future changes

The updated CRM is in use. Its structure and dependencies are documented, an environment is ready for further development, and clear recovery procedures are available. The company retained its familiar tool without building a new system from scratch.

The documentation and procedures remain with the company regardless of who maintains the CRM next. Future changes now have a technical foundation, and anyone responding to a failure will not have to start by investigating a completely unknown system.

Separate project: rewriting a domain manager from Java to Python

In another project, I rewrote an internal domain-management tool for an advertising agency managing hundreds of domains, moving it from Java to Python. This project did require a rewrite. The existing application was the main source of requirements, and the new version needed to retain the functions its users relied on.

Legacy business tools do not all need the same treatment. Sometimes the right approach is to understand the system and organize its environment and maintenance. In other cases, moving to a modern technology stack makes more sense, while preserving the tool's purpose and essential business functions.

When to review an existing system

This work becomes relevant when employees and financial operations depend on an application, but development has stalled. Changes are postponed for fear of disrupting daily work, while knowledge of the system gradually fades.

A full replacement does not have to be the starting point. First, establish how the application works, what it depends on, and what maintenance and recovery require. That makes it easier to plan improvements and decide whether a rewrite is genuinely necessary.

This preparation is useful not only for legacy systems but also for applications about to enter company-wide use. An employee-built AI-assisted tool is one example. See preparing an AI prototype for production for that process. The choice between improving an existing system and replacing it is explored further in approaches to legacy system modernization.