Top Legacy Software Modernization Companies in Europe: Overview for 2027

Plenty of European companies still run core work on software that predates their current size. Eurostat counted 71% of EU SMEs at a basic level of digital intensity or higher in 2025, which leaves them 19 points short of the 90% Digital Decade target for 2030.

In a growing business, the gap shows up the day a new site, store, or clinic goes live. Your stock or booking data sits in a desktop application built for one location, staff copies figures into spreadsheets to bridge the systems, and every new branch adds another manual export.

This article names 7 of the top legacy software modernization companies in Europe for 2027 and sets out the AI tools, industries, and services behind each one. Once you know who fits your stack, the later sections show where AI cuts weeks from a migration and what manufacturing, healthcare, retail, fintech, and energy teams usually modernize first.

TL;DR

Bitkom found AI in use at 57% of German companies with 20 or more staff in 2026, up from 36% a year earlier.
Large EU enterprises adopted AI at more than 3 times the rate of small ones in 2025, which widens the gap for growing firms.
AI shortens discovery, rule extraction, code conversion, and test generation, while engineers still review every change before release.
AI tools map the codebase, and your domain experts confirm each rule, turning undocumented business logic into readable specifications.
Manufacturing, healthcare, retail, fintech, and energy each start modernization from a different system, so sector experience shapes the plan.
A modernization partner should name which stages use AI, which tools run on your code, and where that code runs.
Your architecture, data model, and integration choices made during modernization tend to stay in place for a decade or longer.
7 of the top legacy software modernization companies in Europe include Reenbit, Avenga, Godel Technologies, Inetum, Netcompany, STX Next, and Sii.

Market Signals of Legacy Software Modernization in 2027

AI now sits inside most modernization proposals, and adoption varies widely by company size and sector. These figures show where your business stands. Read them before you set your AI budget:

Bitkom found AI in use at 57% of German firms employing 20 or more people in 2026, up from 36% a year earlier, with 11% running AI agents, based on 603 interviews.
Eurostat counted AI technologies at 17% of small EU firms of 10 to 49 staff in 2025, against 55.0% of firms with 250 or more, in data extracted in December 2025.
Among EU enterprises that considered AI in 2025 without adopting it, 70.9% cited a lack of relevant expertise, 52.5% unclear legal consequences, and 48.8% data protection and privacy concerns, according to Eurostat.
Eurostat data for 2025 shows AI in use at 62.5% of EU enterprises in information and communication, against 10.8% in construction, the lowest of any sector among firms with 10 or more staff.
Data analytics ran on in-house staff at 33% of EU enterprises in 2025, rising to 40% when external providers are counted, according to Eurostat Digital Decade figures extracted in June 2026.

7 Top Legacy Software Modernization Companies in Europe for 2027

A modernization firm takes on the old code, data, and connections that slow your growth and moves them to a platform your team can extend. Your best fit depends on the tools they bring and the sectors they know. The table sets out each firm’s AI toolset, industry coverage, and service scope:

Company	AI Toolset	Industry Coverage	Service Scope
Reenbit	Autonomous AI agents for refactoring and code migration	Manufacturing, construction, healthcare, retail, fintech, energy, facility management	.NET modernization, cloud-native re-architecture, front-end modernization, Azure migration, database migration, CI/CD and DevOps
Avenga	AI-assisted analysis, AI-powered accelerators	Banking and financial services, automotive, life sciences, retail, manufacturing, telecom, energy, transportation and logistics	Application modernization, platform engineering, embedded teams, AI in the SDLC, cloud services, DevOps
Godel Technologies	Godel Factory agentic engineering with Claude	Financial services and insurance, health and life sciences, technology	Legacy modernization, estate mapping, agentic engineering factory
Inetum	refine Analytics, refine redoc, zPLC, r4z Batch, AWS Transform	Aerospace and defense, energy, financial services, healthcare, insurance, manufacturing, public sector, retail, telecom, transport	Discovery and benchmark assessment, health checks, feasibility studies, fixed-time transformation, Migration Factory, transformation outsourcing
Netcompany	Feniks AI with Feniks Learn and Feniks Build	Tax and customs, aviation, digital government, defense, financial services	Core application modernization, application maintenance, operations, cloud and infrastructure
STX Next	AI-powered migration tools, managed AI delivery pods	Financial services, insurance, manufacturing, fintech, eCommerce, transport and logistics, oil and gas	Legacy web systems modernization, ERP modernization, cloud and AWS migration
Sii	GitHub Copilot, Azure AI Foundry, AWS Bedrock	High tech, manufacturing, telecom, banking, insurance, healthcare, automotive, energy, retail, public sector, logistics	Legacy application assessment, re-platforming, refactoring, containerization, database modernization, cloud migration

Reenbit

Founded: 2018
Engagement Options: Tech partnership, dedicated team, IT staff augmentation

Reenbit is a top legacy software modernization company in Europe for businesses in a growth phase whose software has to keep pace with new sites, users, and markets. The AI-powered consultancy and Microsoft Partner employs 100+ engineers, and 88%+ of them hold Microsoft or Azure certifications.

A dedicated team can start in about 3 weeks, and each project opens with a short assessment that weighs code, data, and integrations before anyone commits to a rebuild, re-architecture, or refactor.

Autonomous AI agents take over repeatable refactoring and migration tasks, and CI/CD pipelines check every release before it ships. An energy-sector client now runs key operations in 3–6 seconds instead of 30–40. Brands of Scandinavia, a second client, kept €400,000 in first-year savings, and Cloudbooking reported 27% less maintenance effort with a 99.9% sync rate. Regulated clients get ISO 27001:2022 security controls and builds that follow GDPR.

Why Choose Reenbit

Assessment of 1–2 weeks that sets a rebuild, re-architecture, or refactoring path for each system
100+ engineers, with 88%+ holding Microsoft or Azure certifications
Dedicated team ready to start in about 3 weeks
Energy-sector client operations down to 3–6 seconds from 30–40
First-year savings of €400,000 at Brands of Scandinavia
ISO 27001:2022 certification and GDPR-ready delivery

Avenga

Founded: 2019, through the merger of 4 IT companies
Engagement Options: Embedded nearshore teams, fully managed operations, individual managed services

Avenga runs application modernization in 5 phases: Discover, Decide, Build, Operate, and Improve. Discovery draws on stakeholder input and AI-assisted analysis to map architecture, dependencies, and integrations, and the firm reports a 30–60% productivity gain in planning and requirements at that stage. Approaches range from refactoring and replatforming to microservices and hybrid cloud.

Build work relies on AI-powered accelerators and agile practices, with refactoring, API enablement, and cloud moves for mainframe and core banking systems. For Marginalen Bank, the team moved 300,000 customers from a legacy core to Mambu in 16 months with zero downtime, after 8 dress-rehearsal migrations.

Why Choose Avenga

6,000+ technology professionals across 18 countries
600+ enterprise clients, with 97% choosing a long-term partnership
Marginalen Bank migration of 300,000 customers with zero downtime
Managed services with L1–L3 support and SLA tracking
Full knowledge transfer, with client ownership of code and documentation
Modernization of mainframe, core banking, and telecom OSS/BSS platforms

Godel Technologies

Founded: 2002
Engagement Options: Forward-deployed engineers under client direction, Godel direction, or both

Godel Technologies builds a modernization factory inside the client’s estate, called Godel Factory, where AI agents handle repeatable engineering and people direct the work and sign off critical changes. Each release goes through independent assurance against the client’s own baseline.

Projects start by reverse-engineering the estate as it actually runs. Work then follows business value, risk, and AI readiness, with a keep, change, replace, or shelve verdict for each system. Instem reported 3x faster development cycles and 25% lower operational overhead after modernizing with the firm, and Citation applied the same model across 6 product streams.

Why Choose Godel Technologies

Claude Partner Network Select status
150+ Claude-certified architects and engineers
50,000 hours of R&D on AI-powered delivery
Microsoft Agentic Engineering specialist status
Factory ownership that stays with the client after delivery

Inetum

Founded: 1970, as Gfi Informatique
Engagement Options: Fixed-time transformation projects, Migration Factory, transformation outsourcing, with build and run, build only, or run only

Inetum focuses its modernization practice on mainframe estates, with skills in COBOL, PL/1, 4GLs, and Assembler alongside CICS, IMS, DB2, IDMS, MQ, and Tibco. Engagements open with discovery and benchmarking, health checks, or feasibility studies, then continue as fixed-time projects or a migration factory.

The refine toolset analyzes and redocuments legacy code, and the group also runs COBOL modernization with AWS Transform and agentic AI. Club Med, Renault, and La Mondiale count among references, with 45,000, 33,000, and 10,000 programs respectively, and Interform cut IT run costs by 76% after replatforming.

Why Choose Inetum

200+ modernization projects across 25+ years
OPEX savings of 70–90% after modernization
CNAM platform of 30,000 MIPS serving 60M+ citizens
PMU platform of 10,000 MIPS supporting 24/7 betting
Redocumentation and a knowledge base for simpler handover to new teams
AWS Advanced Consulting Partner status

Netcompany

Founded: 2000
Engagement Options: Consulting and system integration, application maintenance under SLAs, operations in Netcompany data centers or public cloud

Netcompany approaches core application modernization through a composable architecture, adding modular components around aging systems on a low-risk, step-by-step roadmap. Clients choose technology over time and buy only the standard software they need. The plan starts with a close reading of the aging systems.

Feniks AI supports the work with 2 pillars. Its Feniks Learn pillar analyzes the legislation, code, documentation, and business processes behind a legacy system and produces documentation in a few weeks, while Feniks Build targets faster delivery, with development up to 45% faster. Application maintenance then runs on ITIL processes with SLA tracking.

Why Choose Netcompany

9,500+ employees in 10+ countries
Feniks AI with full LLM model independence
Legacy documentation through Feniks Learn in a few weeks
ITIL-based application maintenance with SLA reporting
Data center operations aligned with ISO 27001 and ISO 9000
Partner status with Microsoft, AWS, Oracle, and Google

STX Next

Founded: 2005
Engagement Options: Co-development with in-house teams, managed AI delivery pods, 90-day phases with no lock-in

STX Next modernizes legacy web systems by breaking monoliths into microservices and moving them to the cloud, with AWS migration and sovereign cloud work in the same practice. ERP modernization follows 4 phases, from an Intelligent Assessment over the first 6 weeks to a 90-day pilot and staged expansion. Ongoing maintenance and cost optimization stay available after delivery.

Clients can stop after any 90-day phase and keep the documentation, code, and improvements. Handover takes 2–4 weeks and includes runbooks and infrastructure documentation, and the firm reports moving 500TB+ of enterprise data with 99.9% accuracy.

Why Choose STX Next

ISO 27001 certification
AWS Advanced Tier partner status
Microsoft AI Cloud Partner Program membership
Proof of concept of 6–8 weeks on real client data
Rescue of 8 failed implementations

Sii

Founded: 2006
Engagement Options: Nearshore, offshore, Build-Operate-Transfer

Sii covers application modernization within its cloud practice, from legacy application assessment and a modernization strategy to re-platforming, refactoring, and containerization. Database work moves clients to managed and serverless databases, and the team plans and runs end-to-end cloud migration.

After migration, engineers tune performance and cost, and moves to Microsoft 365, Dynamics 365, Salesforce, ServiceNow, SAP, or Atlassian Cloud fall within the same offer. For Gyldendal, the company converted education platforms from Adobe Flash to React and JavaScript. AI-assisted development runs on GitHub Copilot, Azure AI Foundry, and AWS Bedrock.

Why Choose Sii

7,500+ specialists
ISO 27001, ISO 27018, ISO 9001, ISO 14001, and ISO 13485 certification, plus TISAX
Microsoft, AWS, and Google Cloud technology partner status
Coverage of 22 industry sectors
Application support that can take over service from a previous provider

Where AI Speeds Up Legacy Software Modernization

AI tools now take on parts of modernization that used to need months of manual reading and rewriting. The gains differ by stage, so ask for each one in any proposal you receive. Let’s review the 4 stages where AI changes the pace:

Discovery and Code Analysis

Before anyone changes a line, your team needs a map of the old system: modules, dependencies, dead code, and the integrations nobody listed. AI-based analysis reads the full codebase in days and groups the findings by business capability, which used to take weeks of senior engineering time.

The output still needs a human check. Architects confirm the dependency map against production logs and your own knowledge of the business, and the confirmed map becomes the basis for scope, sequencing, and price.

Business Rule Extraction and Documentation

Old systems often carry rules that exist only in code. AI changes how fast those rules come to light:

Language models trace calculations, validations, and exception paths through code that no current employee has read in full.
Extracted rules turn into plain-language specifications that your product owners and domain experts can review line by line.
Documentation generated from the code gives your new hires a starting point that no longer depends on 1 or 2 veterans.
Each confirmed rule becomes an acceptance test, so the new platform has to reproduce the behavior your business relies on.

Code Conversion and Refactoring

Conversion is where AI promises the biggest savings and where review matters most. Models translate COBOL, VB6, or older .NET code into current languages and suggest refactoring for cleaner structure. Generated code still has to pass your team’s standards for security, performance, and readability, so the realistic gain comes from engineers who edit and approve AI drafts.

Ask any partner for these details:

Share of code AI-generated
Lines engineers rewrote
Review steps per change
Models in use
Where your code runs

Testing and Validation

Proof that the new system behaves like the old one decides when you can switch off the legacy platform. AI shortens that proof in several ways:

Test generation. AI drafts unit and regression tests from extracted rules. Engineers then extend them to edge cases.
Synthetic data. Generated records mimic production patterns without exposing customers. Testing stays compliant when real data cannot leave your environment.
Output comparison. Automated checks run the same transactions through both systems. Your team reviews every mismatch before cutover.
Regression runs. Each release reruns the full suite automatically. Defects surface in hours, long before users report them.

Final Thought

Systems that carried your business through its early growth often become the reason each new site, product, or integration takes longer than planned. The cost of standing still shows up in manual workarounds, scarce skills, and delayed launches, and AI tools now change how quickly that work can move.

Choices made during a modernization tend to outlast the project by a decade or more. Architecture, data model, cloud platform, and the way integrations connect will shape what your team can build long after the partner leaves. The top legacy software modernization companies in Europe treat those decisions as the core of the engagement, so give each one the same scrutiny you would give a new hire for a permanent senior role.