About Simple4u.

Simple4u builds and runs custom AI systems: marketing reporting agents, booking and payment integrations, AI customer service, integrations between the tools you already use. Every system sits under your team. Nobody gets replaced. The marketer gets an analyst, the owner gets a project manager, the front desk gets a night shift.

Founder and CEO in Brooklyn, New York. Engineering office in Kyiv. Since 2023.

We work with small and mid-size businesses that need real software judgment without hiring a full engineering team: a spa in Brooklyn, a yacht charter, a preschool. The work stays specific to the business, not a template.

Why we exist

Custom AI is hired like an engineer, not bought like SaaS. A subscription dashboard cannot read your booking system, post a verdict to your team's Telegram, or hand a real complaint to a person. That takes someone who understands your business and builds for it, then keeps it running as the business changes.

No lock-in: the code we write for you and your data stay yours, so you can leave with everything, any time. Separately, we publish our earlier agent platform (SAE4U Agent, Apache 2) for anyone to read and self-host.

What we do

The AI system comes first: an agent that reads your data, runs a task, answers your customers. Everything else is the work around it, built and run by the same team.

AI systems: marketing reporting agents, customer service, integrations between Gmail, Drive, Calendar, Slack, Jira and your CRM, internal dashboards.
Software development: web, mobile, API. Net new builds, rebuilds, the code the AI system runs on.
Marketing data and SEO: GA4 instrumentation, Search Console, SEO and GEO content, the numbers the reporting agent reads.
Operations and fractional CTO: on-call engineering, sprint work, technical decisions when you do not have a CTO yet.
Creative production: video and content for the channels the marketing system reports on.

The team

Six people. Slava in Brooklyn, founder. In Kyiv: Yurii Shchemelov, co-founder and engineering lead, Nadiya Olefir, project manager, Ihor Zakharov, web designer, Hennadii Knyzhnyk, mobile engineer, Andrii Prylypko, full-stack engineer. The same people who build a system are the ones who run it, no hand-off to junior account managers.

See the full team on /team.

How to start

Four steps, no long sales process:

15-minute call with the founder. What runs your business today, where the hours go.
Free one-page plan in 48 hours. What to automate first, what it connects to, what it costs. Yours to keep either way.
Fixed-price first build. Four to six weeks. Source code in your repository, data in your accounts.
We run it monthly, or you take it over. The monthly option is the retainer World Spa has been on since 2023. Nothing is locked in.

Full breakdown on /how-we-work, or see the FAQ for what's covered, what's not, and how scope is set.

Open source

We publish our own tools on GitHub under Simple4uhq:

SAE4U Agent (Apache 2): the multi-tenant AI agent platform we built as a SaaS product, published when we stopped selling it in May 2026. Self-hostable.
sae4u-memory (MIT): persistent memory architecture for Claude Code and other AI agents. On PyPI.
SHAITS standard: published self-audit framework for trustworthy self-hosted AI. Honest scoring, no marketing claims.

Free to self-host. We engage when clients want help running it in production or building custom integrations on top. More on /open-source.

Founder

Slava Nesterets

Engineer, based in Brooklyn. Started Simple4u as a digital agency in 2023, moved it toward custom AI systems as that became the work clients actually needed.

I run the company hands-on. Every engagement starts with a 15-minute call with me, no SDR, no funnel theater. If a build fits, we start it. If not, I'll say so and point you somewhere else.

Email: office@simple4u.io · Calendly: Book 15 min