Software Maintenance
All activities to fix defects, adapt, optimise and preventively maintain existing software after it goes live.
Software development does not end at go-live. Studies show that 60–80% of total software cost falls in the maintenance phase. Bugs must be fixed, security holes closed, dependencies updated and new requirements integrated. Professional software maintenance keeps your application reliable, secure and performant.
What is Software Maintenance?
Software maintenance covers all activities after go-live that keep the software working, secure and relevant. ISO/IEC 14764 distinguishes four types: corrective (fixing defects), adaptive (adapting to new environments such as new OS or APIs), perfective (improving performance and adding features) and preventive (measures to avoid future problems). A maintenance contract (SLA) defines response times, availability and scope.
How does Software Maintenance work?
Professional maintenance follows a structured process: Monitoring watches the application for errors, performance drops and security threats. A ticket system captures and prioritises reported issues. The maintenance team works through tickets by priority and SLA. Regular maintenance windows are used for updates, patches and optimisation. Quarterly reviews assess overall health and identify proactive measures.
Practical Examples
Security patches: A critical vulnerability in a used library is disclosed – the maintenance team updates the dependency within 24 hours.
Performance: An online shop’s database slows over time – the maintenance service optimises queries and indexes.
API change: A payment provider changes its API – adaptive maintenance updates the integration before the old version is retired.
Server migration: Current hosting is being retired – the maintenance team migrates the application to new infrastructure with no downtime.
Compliance: New GDPR requirements lead to changes in data storage and cookie consent.
Typical Use Cases
Running business-critical applications: Shops, customer portals and internal tools must work reliably
Security: Regular updates and patches protect against attacks and data loss
Technology updates: Frameworks, libraries and runtimes must be kept current
Scaling: Growing user numbers require ongoing performance and capacity work
Compliance: Legal changes (GDPR, eIDAS, PSD2) require regular software updates
Advantages and Disadvantages
Advantages
- Longer lifespan: Maintained software stays relevant and usable for years
- Cost efficiency: Preventive maintenance avoids expensive emergency fixes and outages
- Security: Regular patches close known vulnerabilities quickly
- User satisfaction: Stable, performant software keeps customers and staff satisfied
- Compliance: Continuous adaptation to legal and regulatory requirements
Disadvantages
- Ongoing cost: Maintenance contracts cause monthly or annual cost (typically 15–20% of development cost per year)
- Knowledge dependency: The maintenance team must know the software deeply – changing is costly
- Prioritisation: Maintenance competes with new features for budget and capacity
- Technical debt: Without refactoring, technical debt can still grow despite maintenance
Frequently Asked Questions about Software Maintenance
What does software maintenance cost per year?
What should a maintenance contract (SLA) include?
Can you do software maintenance in-house or do you need a vendor?
Related Terms
Want to use Software Maintenance in your project?
We are happy to advise you on Software Maintenance and find the optimal solution for your requirements. Benefit from our experience across over 200 projects.