8 of 11
critical federal legacy systems reviewed in 2025 used outdated programming languages.
U.S. GAO legacy systems reviewFree custom application white paper
When Off-the-Shelf Stops Fitting
Compare buying, adapting, and building software when your current tools no longer fit. Learn how to plan a first release and account for long-term support.
- 11-page guide
- Includes research and links to sources
- Download the PDF after filling out the form
Inside the guide
What you’ll learn
- Signs you’ve outgrown a tool or workaround
- Questions to help you compare new software with changes to your existing tools
- Five checks to make before committing to custom development
- A plan for a small first release, a data migration checklist, a cost model, and a 90-day project outline
From the research
Research cited in the guide
Here are a few findings discussed in the guide. Follow the source links for the full studies and their context.
3 of 11
had modernization plans containing all three leading planning elements GAO assessed.
U.S. GAO legacy systems reviewIncremental
development with continuous evaluation reduces the risk of funding outdated or unsuccessful technology.
GAO Agile Assessment GuideCommon questions
Before you download
When is custom software worth building?
It can make sense when the work is important to your business and available products can’t meet your essential needs at a reasonable cost. You also need a plan for maintaining the application, protecting its data, and adapting it over time.
Should we improve the process before building?
Usually, yes. Map how the work happens, remove unnecessary steps, and agree on who is responsible for each part. Otherwise, you risk building the same problems into the new application.
What should the first release include?
It should let people complete one important task from start to finish. That includes the permissions, reliable data, error handling, and support the task needs, along with a way to compare results with the old process.
Want help applying the guide?
Tell us about the task or system you’re working on. We can help you assess the options, plan a trial, or get the project started.