120+
legacy screens migrated to React
60%
faster page loads on migrated screens
Mo→wk
release cadence, monthly to weekly
5
Dillo engineers embedded with the client's team
The Client
An established HR software vendor whose applicant tracking system serves recruiting teams at hundreds of mid-market companies. The product is a workhorse — requisitions, candidate pipelines, interview scheduling, offer workflows, compliance reporting — and it wins deals on depth of functionality, not on looks.
The Challenge
That depth came at a price. The front end was more than a decade of accumulated jQuery, server-rendered pages, and inline scripts, tightly coupled to a C#/.NET back end whose endpoints returned HTML fragments as often as data. Pages loaded slowly, mobile use was effectively impossible, and prospects increasingly compared the UI unfavorably against younger competitors.
Worse, the codebase had become hostile to change: every feature touched global state, regressions surfaced in unrelated screens, and the team had retreated to monthly releases with a long manual QA cycle. Leadership had rejected a full rewrite — too risky for a revenue-critical product — but hiring senior front-end engineers locally had gone nowhere for two quarters. They needed experienced people who could execute an incremental migration inside the existing team, starting now.
What We Did
Dillo assembled a five-engineer augmented pod — four senior front-end engineers with React/TypeScript depth and one full-stack C#/.NET engineer for API work — vetted against the client's stack and interviewing bar. The pod joined the client's standups, sprint rituals, and code review from day one, reporting to the client's VP of Engineering.
- Established a strangler-style migration architecture: a React/TypeScript shell mounted inside the legacy app, so new and old screens coexist and users never notice a seam.
- Migrated the product screen by screen behind feature flags, starting with the highest-traffic recruiter workflows, with instant rollback per screen.
- Built a shared component library and design tokens with the client's designer, so migrated screens converged on one consistent UI.
- Modernized the API layer alongside: the embedded .NET engineer converted fragment-returning endpoints into clean, versioned JSON APIs on SQL Server-backed services.
- Added automated testing and CI gates — component tests, Playwright end-to-end flows for critical recruiter journeys — cutting the manual QA cycle that had anchored releases to a monthly rhythm.
- Ran knowledge-transfer sessions so the client's own engineers worked in the new stack from the first month, not after a handover.
The Results
- More than 120 legacy screens migrated to React/TypeScript with no big-bang cutover and no customer-facing migration incidents.
- Migrated screens load about 60% faster, and recruiters can finally work from tablets in interview rooms.
- Release cadence moved from monthly to weekly, backed by feature flags and automated test gates.
- The vendor's sales team stopped losing demos on UI; the modern front end became a talking point instead of an objection.
- The pod remains embedded, now splitting time between finishing the long tail of screens and shipping new product features.
Figures reflect outcomes reported for this engagement; they are project results, not audited benchmarks.
Tech Stack
Services Used
IT Staff Augmentation — a five-engineer pod embedded in the client's product team.