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Case study · Applicant tracking and hiring · USA

Enterprise ATSSix people rebuild a US hiring platform for 1,000+ companies and 2.5M candidates with no pause in hiring

A large US hiring platform, under NDA: the applicant tracking system more than 1,000 client companies run their hiring on, with 2.5 million candidates in it. I am its only CTO, on a fractional contract, so the company gets full technical leadership at a fraction of the cost of a full-time executive. I lead a team of six that is rebuilding the legacy system as a new one on modern technology, a job that usually takes a whole department, and the team ships a release every two days along the way. I designed the architecture so one platform serves very different clients, defense and healthcare among them, under each one's compliance rules and with no separate build for any of them.

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Client
Under NDA
Product
Applicant tracking system (ATS)
Market
USA
Industries
Defense, healthcare and other regulated sectors
Client companies
1,000+
Candidates
2.5 million in the system
My role
Fractional CTO, and the company's only CTO
Team
6 people
Releases
Every two days

In numbers

candidates in a system six people are rebuilding from legacy
2.5M
client companies, defense and healthcare among them, hire on it
1,000+
between releases, even in the middle of a full rebuild
2 days
people rebuilding a platform that usually takes a department
6
me, fractional: full technical leadership at a fraction of the cost
1 CTO
the whole system rebuilt while clients keep hiring
Legacy → new
01

The starting point

An applicant tracking system is where an employer's hiring lives: every opening, every candidate, every interview and every offer. This one is large, and it grew up on a legacy system that made every change slow and expensive.

Its clients are US employers, many of them in industries with strict rules on who may see what, such as defense and healthcare. The old system could not stretch to serve all of them. It had to be rebuilt as a new one without stopping anyone's hiring, and the company brought me in to own the whole job.

02

What we did

  1. The only CTO

    I am the company's only CTO, on a fractional contract. Everything technical is mine: the architecture, the team, the plan and the decisions. The company has one accountable owner for all of it without paying for a full-time executive.

  2. A full rebuild by a team of six

    I lead a team of six that is rebuilding the legacy system as a completely new one, on new technology and built for the AI era from the first line. A rebuild this size usually takes a whole department, and here six people carry it.

  3. A release every two days

    The team ships a release every two days, in the middle of a full rebuild. Clients get improvements continuously instead of waiting for one big switch, and each step is small enough that nobody's hiring has to stop for it.

  4. One architecture for more than 1,000 clients

    I designed the architecture so one platform can serve more than 1,000 very different client companies, each with its own structure, workflow and rules. All of them run on the same code, so the team builds, tests and maintains one system instead of a fork for every customer.

  5. Compliance built into the architecture

    Defense, healthcare and other regulated industries each bring their own compliance requirements. The platform meets them from the architecture up, so the company can sell to the most demanding employers in the US.

  6. Every step of a hire in one system

    The new platform covers the whole hire: careers sites that search engines index, résumés parsed straight into the application form, interviews scheduled against the team's real calendars, structured scorecards, offers signed in the browser, and a portal where each of the 2.5 million candidates in the system sees where they stand. An employer runs all of it in one product instead of paying for a stack of separate tools.

03

The result

A US hiring platform with 2.5 million candidates and more than 1,000 client companies is moving off legacy onto a new system built for defense, healthcare and other regulated employers, and its clients keep hiring through the move. A team of six ships a release every two days, where a rebuild this size usually takes a department, and one fractional CTO owns all of it.

oleg.isSent on request

Full case · PDF

Enterprise ATS

Six people rebuild a US hiring platform for 1,000+ companies and 2.5M candidates with no pause in hiring

  1. 01The architecture of the new platform
  2. 02From legacy to new without stopping anyone's hiring
  3. 03One codebase for very different clients
  4. 04Compliance for defense, healthcare and other regulated industries
  5. 05The team of six: how it does a department's work with AI
  6. 06The plan and where it stands
Prepared by Oleg SotnikovPDF

The full Enterprise ATS case

The public story stops here. The PDF has the rest: the architecture before and after, the migration plan, how the team works with AI agents, what it all costs to run and where the savings came from.

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