Companies across Europe already know their core software needs work, and the people who keep it alive are getting harder to replace. A Lünendonk study from July 2025 found that in every 2nd company surveyed, operating, maintaining, and developing legacy systems is not secure over the medium to long term.
For your business, that risk usually sits with a few long-serving staff and a database nobody fully trusts. Once they leave, the rules behind invoices, stock levels, or patient records leave with them, and moving the data becomes guesswork.
This guide lists 7 of the top legacy software modernization companies in Europe for 2027 and explains what each one handles, so you can find help for your own systems.
TL;DR
- ENISA traced about 60% of 4,875 analyzed EU incidents back to phishing as the first point of entry.
- Only 25% of EU businesses made ICT security training compulsory for staff in 2024.
- Old systems need a security plan during modernization, since unsupported code stays exposed until the switch-off.
- Isolating what you cannot patch and tightening access during migration close the most common gaps.
- Security built into the new platform from day one costs far less than controls added after launch.
- Your staff adopts a new system faster when they hear the reason early, and test releases themselves.
- Short training cycles and an open feedback channel keep productivity stable through each release.
- 7 of the Top legacy software modernization companies in Europe for 2027: Reenbit, Nortal, Helmes, Cegeka, Netcetera, BlueSoft, and ELCA.
Insights into Legacy Software Modernization in 2027
Security and skills now shape modernization plans as much as budgets do. These figures show where the risks and the gaps sit for European companies. Plan your project around them:
- ENISA analyzed 4,875 incidents in the EU between July 2024 and June 2025 and found phishing behind about 60% of initial intrusions, with vulnerability exploitation second at 21.3%, according to its Threat Landscape 2025 report.
- Eurostat reports that about 60% of EU businesses made staff aware of their ICT security obligations in 2024, while 43% offered voluntary ICT security training and only 25% made such training compulsory.
- Strong password authentication reached 96.8% of large EU enterprises in 2024 against 82.0% of small ones, and 49.6% of all enterprises used a VPN, according to Eurostat’s survey on ICT security.
- In a Lünendonk study from July 2025, 74% of IT and business leaders expected AI to eventually find and partly fix security gaps in legacy systems, and 69% hoped it would improve code understanding.
- Eurostat found that 40% of EU citizens aged 16 to 74 lacked at least basic digital skills in 2025, while the Digital Decade target calls for 80% with basic skills or better by 2030.
Top Legacy Software Modernization Companies in Europe in Details
Modernization firms carry your code, data, and access rights from an aging platform to one your team can secure and extend. Their security habits and AI tooling decide how safely that move goes for your business. The table pairs the security focus of each firm with the AI tools in their delivery:
| Company | Security Focus | AI Toolkit |
| Reenbit | ISO 27001:2022 controls, GDPR-compliant builds, secure RESTful APIs | Autonomous AI agents for refactoring and code migration |
| Nortal | Human-set security and compliance boundaries, cyber resilience services, ISO 27001 | AI Legacy Archaeology, AI-First Delivery Accelerator, Agentic Code Review |
| Helmes | Penetration testing, threat modeling, code security reviews, red team assessments, NIS2 readiness | AI value scan, AI agents |
| Cegeka | Cybersecurity and regulatory checks in every modernization assessment, GDPR and GxP compliance services | Cognitive Codescape approach for mapping legacy code |
| Netcetera | Threat modeling, security-by-design reviews, penetration testing, PCI-DSS and DORA expertise | DocDive, Phivea AI platform |
| BlueSoft | AI security and regulatory compliance, software supply chain security, on-premises AI toolkit | ModernAIze with Chat with Code, StarBoost |
| ELCA | Sovereign cloud hosting, FINMA, GDPR, and nDSG compliance, ISO 27001 | AI-enhanced migration and integration |
Reenbit
- Founded: 2018
- Services: Legacy .NET upgrades, Azure cloud migration, cloud-native redesign, database and front-end modernization, DevOps pipelines
- Expertise: Security-first modernization of .NET platforms on Azure
Reenbit is a top legacy software modernization company in Europe for scale-ups that still run on their first-generation software, where a security gap or an outage now costs far more than it used to. The AI-powered consultancy and Microsoft Partner keeps security in line with ISO 27001:2022 and GDPR from assessment to release.
A team of 100+ engineers carries out the work, and 88%+ of those engineers hold Microsoft or Azure certifications. Modernization moves in phases while the legacy platform stays live, and secure RESTful APIs let new applications reuse legacy rules without opening the core. Autonomous AI agents handle repeatable refactoring, and every release passes CI/CD checks.
For an energy-sector client, response times on key operations fell to 3–6 seconds, compared with 30–40 earlier. Brands of Scandinavia counts €400,000 in savings from year one, and Cloudbooking spends 27% less effort on maintenance.
Nortal
- Founded: 2000
- Services: AI-driven legacy modernization, IT outsourcing, AI-native teams, cyber resilience
- Expertise: Legacy reconstruction with human-in-the-loop AI
Nortal approaches legacy modernization in 3 stages: AI-driven archaeology that documents how a system actually behaves, AI-guided reconstruction, and controlled modernization with human-in-the-loop verification. Coding modes range from human-driven work to an agentic swarm, and people set the security and compliance boundaries at every stage.
Engagements can start with an AI Discovery Workshop or a focused 6-week pilot. In one published project, the team rebuilt a legacy application in 10 days with zero lines of old code, and another 6-week effort reported delivery efficiency gains above 50%. AI Legacy Archaeology produces structured documentation that stays with the client team.
Helmes
- Founded: 1991
- Services: Legacy software modernization and maintenance, software value and risk assessment, secure software and cybersecurity services
- Expertise: Faster releases on long-lived codebases
Helmes modernizes and maintains legacy software and pairs that work with a security practice covering penetration testing, threat modeling, red team assessments, and NIS2 readiness. Projects open with a software value and risk assessment that ends in an executive summary with cost and risk estimates, and one such assessment took less than 2 weeks.
The firm follows a 4-step approach: map the current situation, propose improvements, agree on a roadmap, then start the work. For an insurer, releases moved from every 2–3 months to daily deployments with zero downtime, and a marketplace launched in 3 months against a planned 1.5 years.
Cegeka
- Founded: 1992
- Services: Application advisory services, 6R Scan, Application Management Services, hybrid cloud
- Expertise: Modernization roadmaps for public sector, energy, finance, and manufacturing clients
Cegeka runs application modernization as an advisory service built on a 6R Scan that weighs rehosting, replatforming, refactoring, retiring, and related paths for each application. Every assessment checks cybersecurity, regulatory compliance, and cloud readiness, and workshops turn the findings into a modernization roadmap with visual reports. Clients can book a free first consultation before the scan starts.
After modernization, Application Management Services provide 24/7 support, and the group holds Microsoft Azure Expert MSP status for cloud operations. Separate GDPR and GxP compliance services and a training offering support clients in regulated sectors such as government, energy, finance, and manufacturing.
Netcetera
- Founded: 1996
- Services: Legacy banking system modernization, cloud-native delivery, security engineering, financial technology consulting
- Expertise: COBOL and assembler modernization for banks and payment providers
Netcetera modernizes legacy banking systems step by step, with no big-bang migrations, through 4 phases: understand, plan, deliver, and operate and evolve. AI supports code analysis, code translation from COBOL and assembler, synthetic test data, and documentation, which the firm says cuts analysis from years to weeks.
Security engineering runs through every project, with threat modeling, security-by-design reviews, and penetration testing, along with expertise in PCI-DSS, DORA, eIDAS 2.0, and GDPR. Operations continue after go-live under service levels aligned to DORA, and AI-generated business-logic documentation keeps system knowledge searchable for client teams.
BlueSoft
- Founded: 2002
- Services: AI-driven IT modernization, transition services, platform engineering, system integration, cloud migration
- Expertise: Strangler-based modernization of Java, .NET, and PL/SQL systems
BlueSoft combines AI-driven IT modernization with transition services that run through 7 phases, from discovery and transition planning to stabilization, technology debt reduction, and extensive support. The ModernAIze toolkit lets engineers chat with legacy code, plan strangler-based modernization, and generate documentation that captures tacit knowledge.
Work covers Java, .NET, and PL/SQL-based systems and monoliths, with platform engineering, system integration, and cloud migration in the same practice. ModernAIze can run on-premises, and the firm offers AI security, regulatory compliance, and software supply chain security services for clients with strict data rules.
ELCA
- Founded: 1968
- Services: Legacy assessment, modernization strategy, implementation and deployment, cloud-native development, managed delivery
- Expertise: Mainframe-to-cloud and monolith-to-microservices migration
ELCA covers application modernization in 3 stages: assessment of a legacy system or portfolio, a modernization strategy, and implementation. Options range from encapsulation and rehosting to refactoring, rearchitecting, rebuilding, and replacement, delivered incrementally or in one step. Integration with the client’s own teams is also possible.
Engagements can stay at assessment level or extend to full managed delivery. Hosting options include ELCA Cloud Services, a sovereign cloud with FINMA, GDPR, and nDSG compliance, and an AWS Strategic Collaboration Agreement supports cloud-native builds. ISO 27001 certification dates back to 2017, alongside ISO 9001 and ISO 14001.
Securing Legacy Systems While You Modernize Them
A migration can take months or years, and the old platform keeps running and stays exposed the whole time. Your security plan has to cover both systems until the last module moves. Protect your business with these 5 tips.
Map the Attack Surface of the Old System
You cannot protect what nobody has listed. Before the migration starts, your team and partner should record every entry point into the legacy platform, from user logins to forgotten service accounts and file transfers to partners. That inventory shows where to spend effort first. Cover these areas:
- User accounts
- Service accounts
- Open network ports
- Partner file transfers
- Outdated libraries
Patch What You Can, Isolate What You Cannot
Some components still receive vendor fixes, and those patches should go in on a fixed schedule. Others run on operating systems or frameworks that left support years ago, and no patch will ever arrive for them.
For those parts, isolation works better. Placing them in a separate network segment, behind a gateway that filters traffic, limits what an attacker can reach and buys your team time until the module moves to the new platform.
Lock Down Access During the Migration
Migration projects open temporary doors that attackers look for. Close them with these measures:
- Grant each engineer only the access their current task needs, and remove it the day that task ends.
- Require multi-factor authentication for every account that touches production data, including partner and contractor accounts.
- Log every administrative action on the old and new systems so your security team can trace changes later.
- Review access lists every month, since project teams change faster than permissions usually do.
Protect Data in Transit Between Old and New
Data moves back and forth while both systems run, and each transfer is a chance to leak it. Secure these flows:
- Encryption. Every file and API call between systems uses current encryption. Your team retires old protocols such as plain FTP before migration starts.
- Masked test data. Test environments receive anonymized copies of production data. Real customer records stay in production.
- Integrity checks. Checksums and record counts confirm that nothing changed on the way. Your team spots tampering or loss at once.
- Retention rules. Temporary copies and exports carry a deletion date. Nothing lingers on shared drives after the move.
Build Security Into the New Platform From Day One
The new system should arrive with security in place, not as a later project. Current authentication, role-based access, encryption at rest, and structured logging belong in the first release, along with automated security tests in the delivery pipeline.
That approach costs far less than retrofitting controls after launch. It also gives your auditors a clean record from the start, and your team stops carrying the risks of the old platform into the new one.
Framework to Keep Your Team on Board During a Legacy Software Modernization
A new system succeeds only when the people who use it every day accept it. Resistance, workarounds, and quiet return to old spreadsheets can undo months of engineering. Use this framework to bring your team along.
Explain the Reason Before the Change
People accept change more easily when they understand why it is happening. Start your communication with these messages:
- Share the specific problems the old system causes, such as slow reports or manual exports, so staff see the change as a fix for their own frustrations.
- Explain what stays the same, since knowing which routines continue lowers anxiety about everything else.
- Give a realistic timeline with dates for each release, so nobody hears about a switch-off for the first time a week before it happens.
- Name a sponsor in leadership who answers questions openly and stays visible throughout the project.
Involve Key Users From the First Sprint
Early involvement turns potential critics into champions. Build these roles into your project:
- Process owners. Experienced staff confirm business rules before developers rebuild them. Their input prevents costly gaps later.
- Pilot testers. A small group tries each release before everyone else. Their feedback shapes the final version.
- Department champions. One person per team answers everyday questions. Colleagues ask a peer before they file a ticket.
- Feedback reviewers. Users rate each sprint demo. The team adjusts priorities based on their scores.
Train in Short Cycles Before Each Release
Long training sessions months before launch rarely stick. Short, focused sessions shortly before each module goes live work better, because people practice the new screens while they still remember them.
Recorded walkthroughs, quick reference guides, and a test environment with realistic data let your staff learn at their own pace. Track how many people complete each session, and follow up with anyone who missed it before their team switches over.
Open a Feedback Channel That People Use
Staff notice problems long before dashboards do, yet they only report them when the channel is simple and someone visibly responds. A dedicated chat channel or form, monitored daily during each rollout, keeps issues from turning into quiet workarounds. Share what changed because of the feedback, so people keep using it. Track these signals in your rollout:
- Open tickets per release
- Time to first response
- Repeat questions
- Usage of old tools
- Satisfaction scores
Mark the Switch-Off as a Team Milestone
The day the old system goes dark deserves recognition. A short announcement, thanks to the people who tested and trained others, and a clear note on what happens next give your team a sense of closure.
That moment also signals that the old way is gone for good. Without it, staff tends to keep private copies of old reports and spreadsheets, and the workarounds the project meant to remove slowly come back.
Wrapping Up
Modernization changes more than code. During the move, the old platform stays exposed to attacks, and the people who rely on it face new screens, new routines, and a fair amount of uncertainty. Projects that ignore either side tend to finish late, over budget, or with users who never fully switch.
The top legacy software modernization companies in Europe plan for both from the first week, with security controls for the old and new systems and a clear path to bring your staff along. When you compare partners, ask how they protect data during migration and how they handle training and feedback, and give real weight to the answers.
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