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Legacy Modernization: 4 global agencies to consider

Four global Legacy Modernization agencies: Thoughtworks, Persistent Systems, SoftServe, GlobalLogic. Sources linked; the order is not a ranking.

Agencies shortlisted for modernizing existing systems with controlled, incremental change.

AgencyHQBest for
ThoughtworksChicago, USA (founded there, per its site)Business-critical systems requiring careful incremental change.
Persistent SystemsPune, IndiaEstablished software products needing architectural renewal.
SoftServeAustin, Texas, USA; engineering roots in Lviv, UkraineModernization linked to cloud and infrastructure changes.
GlobalLogicSan Jose / Santa Clara, California (sources vary)Modernizing existing products while continuing to develop new capabilities.
Shortlisted

Thoughtworks

Best for: Business-critical systems requiring careful incremental change.

Dedicated modernization practice with published technical work on understanding and evolving legacy systems.

In this category:

  • Dedicated modernization practice with published technical work
  • Incremental change of business-critical systems
HQChicago, USA (founded there, per its site)
Founded1993
Team10,000+ people; 47 offices in 18 countries
Named clientsNestle Brazil (named on its site)
Partners & badgesMicrosoft, AWS, Google Cloud, Databricks and Snowflake partner; AWS Global Partner of the Year for data and analytics (2025)

Services

Software engineeringData engineeringLegacy modernizationDesignAI-powered productsEngineering practice improvement

Best at

  • Dedicated modernization practice with published technical work
  • Incremental change of business-critical systems

Also offers

  • Data engineering and analytics
  • Product and experience design
  • AI/works and Agent/works platforms
  • Continuous delivery and engineering practice improvement
Source: capability pageFacts from the company’s own website and public sources, checked 16 Oct 2026. Not a ranking.
Shortlisted

Persistent Systems

Best for: Established software products needing architectural renewal.

Product modernization includes cloud-native architecture, microservices, APIs and containerization.

In this category:

  • Cloud-native architecture, microservices, APIs and containerization
  • Architectural renewal of established products
HQPune, India
Founded1990
Team29,500+ employees in 21 countries (its site)
Named clientsIntuit, Mercedes-Benz, ANZ Bank, Johns Hopkins, Mount Sinai
Partners & badgesAWS, Google, Microsoft, Databricks, Snowflake, Salesforce and others listed as partners

Services

Software product engineeringProduct modernizationCloud and infrastructureData and analyticsAIEnterprise integration

Best at

  • Cloud-native architecture, microservices, APIs and containerization
  • Architectural renewal of established products

Also offers

  • Cloud and infrastructure
  • Data and analytics
  • Enterprise integration and ERP transformation
  • CX transformation
Source: capability pageFacts from the company’s own website and public sources, checked 16 Oct 2026. Not a ranking.
Shortlisted

SoftServe

Best for: Modernization linked to cloud and infrastructure changes.

Application modernization, cloud migration, platform engineering and supporting operational disciplines.

In this category:

  • Application modernization with cloud migration
  • Platform engineering and operational disciplines
HQAustin, Texas, USA; engineering roots in Lviv, Ukraine
Founded1993
TeamAbout 10,000 people; 54 offices in 17 countries (third-party, 2026)
Named clientsMontblanc, Ensight, Quavo, Zenoss
Partners & badgesAWS Premier Tier Partner; NVIDIA Elite Partner; Google Cloud Premier Services Partner

Services

Application modernizationCloud migrationAIDevOpsData and analyticsIoT and robotics

Best at

  • Application modernization with cloud migration
  • Platform engineering and operational disciplines

Also offers

  • DevOps and platform engineering
  • FinOps
  • IoT, robotics and XR
Source: capability pageFacts from the company’s own website and public sources, checked 16 Oct 2026. Not a ranking.
Shortlisted

GlobalLogic

Best for: Modernizing existing products while continuing to develop new capabilities.

Technology modernization alongside software product engineering.

In this category:

  • Modernizing existing products
  • Continuing to develop new capabilities at the same time
HQSan Jose / Santa Clara, California (sources vary)
Founded2000; owned by Hitachi since 2021
TeamAbout 32,000 people in 25 countries (Hitachi, via search)
Named clientsEricsson and Cox Automotive appear in its case study images
Partners & badgesA Hitachi Group company

Services

Software product engineeringTechnology modernizationProduct strategy and experience designDigital business transformationEmbedded engineering

Best at

  • Modernizing existing products
  • Continuing to develop new capabilities at the same time

Also offers

  • Digital business transformation
  • Intelligence engineering
  • Embedded engineering and IT/OT transformation
Source: capability pageFacts from the company’s own website and public sources, checked 16 Oct 2026. Not a ranking.
How this shortlist was made: agencies were chosen for relevant public work, depth in the category and coverage across the project lifecycle, based on public evidence, mainly provider sources. Team quality and comparable client references still need checking before selection. See How We Choose.

How to choose

  • Ask how they understand the old system before changing it.
  • Prefer incremental plans over big-bang rewrites.
  • Clarify how business continuity is protected.
  • Check cloud, data and integration experience.

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