PUBLISHED DATE: 2026-02-15 19:12:44

Legacy System Modernization with AI | Slingshot | Publicis Sapient

Modernize Legacy Systems Faster with AI

Modernize Legacy Systems Faster with AI
Sapient Slingshot uses AI to extract business logic, generate new code and validate it so decades of tech debt turn into production-ready platforms faster and with less risk.
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Inside AI-assisted code modernization

Discover how Slingshot agents modernize legacy code in a few short clicks in this interactive demo.
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Slingshot powers our legacy modernization

Slingshot modernizes and builds software by automating the entire SDLC with enterprise context for fast, governed, production-ready code.

Slingshot powers our legacy modernization

Slingshot powers our legacy modernization

Slingshot modernizes and builds software by automating the entire SDLC with enterprise context for fast, governed, production-ready code.

Why Slingshot for legacy modernization?

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Ship faster without full rewrites

Move from multi-year rebuilds to steady, incremental modernization.

Preserve business logic

Extract and carry forward rules and dependencies.

Reduce risk with provable accuracy

Validate modernized systems against original behavior before release.

From maintenance to innovation

Free teams from legacy drag to focus on new products and capabilities.
Slingshot legacy modernization interface

From legacy code to verified specifications to modern code

Slingshot turns legacy code into a clear specification, then uses it as the source of truth to design and generate modern, production-ready code.

Modernization archetypes

Modernization archetypes

Slingshot modernizes legacy technologies across every layer of the enterprise, preserving business logic while transforming systems into modern, cloud-ready architectures with up to 99 percent code-to-spec accuracy.
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Fresh features and thinking on how teams can build, run and scale with AI.

Customer stories

Leading organizations use Slingshot to modernize legacy systems.

Health

Health Care Organization Goes Cloud-Native
Healthcare organization goes cloud-native

The Problem

A leading health care benefits provider needed to modernize 10,000+ COBOL and Synon mainframe screens to improve claims processing and customer service.

Our Solution

With Slingshot, the provider uncovered hidden business rules and dependencies, enabling faster, safer migrations. Automated test generation sped up QA while reducing manual errors.
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Energy & Commodities

RWE Modernizes a Legacy App in Two Days

The Problem

RWE faced an operational risk: a number of aging, undocumented applications were running on outdated technology stacks.

Our Solution

Slingshot, paired with human oversight, helped RWE revive a 24-year-old app with no source code or documentation in two days.
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What our customers say

" Beyond the tools, it’s the reimagined end-to-end development process with a human in control that I found impressive—it was a real eye-opener. "
— Ryan Brudenell
Head of Digital and IT Solutions, RWE Generation UK Ltd.

FAQs

Before you rethink how legacy code becomes modern software, here’s what enterprise teams want to understand first.

What makes Slingshot different from traditional legacy modernization tools?

Traditional modernization tools jump straight from old code to new code, which introduces risk and breaks undocumented business logic. Slingshot inserts a specification layer between legacy and modern systems. It reads existing code, extracts the business logic and converts it into a clear, testable specification. That specification becomes the source of truth used to design and generate modern code with full traceability. This is what allows Slingshot to modernize faster without losing accuracy or control.
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How does Slingshot preserve critical business logic during modernization?

Slingshot analyzes legacy code to identify rules, dependencies and behaviors that are often undocumented or locked in the heads of SMEs. That logic is captured as a machine-readable, testable specification before any new code is generated. Because the specification drives the transformation, Slingshot ensures the modern system behaves exactly as the original—only cleaner, faster and easier to evolve. This reduces dependency on scarce legacy experts and lowers modernization risk.

What types of legacy systems can Slingshot modernize?

Slingshot is designed for large, complex enterprise systems, including:
It is particularly effective where systems are business-critical, poorly documented and too risky to rewrite manually.

How accurate is Slingshot when generating modern code?

Slingshot generates modern code directly from the specification and design, not from guesswork or prompts. Because every line of output code traces back to a verified specification, Slingshot delivers up to 99 percent code-to-spec accuracy. This traceability makes modernization auditable, testable and suitable for regulated environments.

How does Slingshot reduce risk compared to rewrite or replatform approaches?

Rewrite and replatform strategies often fail because they rely on assumptions about how legacy systems work. Slingshot reduces risk by:
This allows teams to modernize incrementally and confidently, rather than betting everything on a single cutover.