Clients in one database
Shared tables with a client column, a schema per client or separate databases for those whose contracts require it, chosen on your numbers.
For owners who built their own system, with AI or without
Your company tool, sold to other companies
You built a TMS, a CRM or a scheduling app for your own company, maybe with Claude or Lovable. It works, and other companies ask to buy it. Today each of them would need a separate copy. I turn it into one product for many clients, without rewriting what already works.
- “someone you can always count on”public LinkedIn recommendation
- “a true bias for action”client CTO, on LinkedIn
- 15+ yearsshipping software
- Free call, no pitch deck30 minutes, then you decide
What changes in your app
Sign-up, invitations and roles
A new company signs up, invites its people and gets the right permissions without you touching the database.
Billing and invoices
Plans and subscriptions with Stripe or Polish payment providers, invoices that can go to KSeF.
One deploy for everyone
A release updates every client at once, and a single client can be restored on its own.
How it works
Pick the model
Clients now and in two years, contracts, what differs between clients. The free calculator gives a first answer.
Four to ten weeks
The changes in your code, with your own company moved in as the first client and nothing lost.
First paying clients
The first three clients onboarded with you, so you see where they get stuck.
Then I can stay
As the engineer of the product, a few days a month or more, as it grows.
Where it fits
- A company tool other firms in your industry already ask about.
- An MVP built with Lovable, Bolt, Replit or Claude that now has paying clients.
- A separate copy per client that has become too many servers to update.
Proof
I was the founding engineer of Sandtime.io, a time-tracking SaaS: multi-tenant routing, SSO, Paddle and Mac App Store subscriptions and eight platforms from one codebase, in production since 2018. Check your own case in the free multi-tenant calculator.
Sandtime.io: founding engineer, eight platforms, one codebase
- The problem
- A time-tracking SaaS had to live where people work: desktop tray, browser, phone and app stores.
- What I did
- I authored the original product vision and architecture in 2018 and made the first commit. React Native wrappers for iOS and Android, Electron for macOS, Windows and Linux, a Chrome extension, multi-tenant routing, SSO, Dockerized services, Paddle and Mac App Store subscriptions, CI/CD.
- Result
- Eight platforms shipped and run in production. The only engineer active in every year of the product, 8,000+ commits and close to half of all merges to trunk.
See also: Mobile & desktop apps · SaaS & MVP
Restarting delivery after three years of maintenance mode
- The problem
- A mature product had drifted into maintenance. The backlog was old and the team small.
- What I did
- Agent-assisted development under an enforced rule set, help docs migrated from WordPress into the repo as markdown with 301 redirects and i18n, help added to the Definition of Done.
- Result
- Commit volume up about 40× year over year in 2026, one less server to break during holidays, docs that match the product.
See also: AI & agents · AI in your company
Taking over growth: SEO, GEO and dashboards leadership reads
- The problem
- Organic acquisition was close to zero and nobody could say which feature moved which number.
- What I did
- A tracking plan per feature, PostHog KPI dashboards, SEO and GEO work on landing pages and help, with help, changelog and landing pages treated as one body of context for people and bots.
- Result
- Organic acquisition grew from near zero and leadership gets its numbers from dashboards, not from asking. Numbers stay relative on purpose.
See also: PostHog & product analytics
Your company tool, sold to other companies
You built a system for your own company and other companies want it. I turn it into a multi-tenant SaaS: clients in one database, sign-up, roles, billing, one deploy for everyone, your company moved in as the first client.
FAQ
Questions
Do we have to rewrite the app?
Usually not. The client identifier goes into the tables and the queries, login learns which client a person belongs to, and your own company becomes the first client.
What about clients who want a separate database?
They get one, on the same code and the same release, often as a higher plan.
Can you also become our technical partner?
Yes, as a paid engineer of the product after the build, a few days a month or more. We decide after the first clients, on numbers.
How long does it take?
Four to ten weeks, depending on how many separate copies you run today, separate databases and per-client fields.
Let’s find out in 30 minutes
A free 30-minute call. You bring the problem, I bring questions. No prices on this page because scope comes first.
If I am the wrong person I will say so on the call and point you to someone better.
or write to ciunkos@gmail.com
After you book: a calendar invite, then the call. Nothing else to fill in.
Available from November 2026 · B2B contract or employment · Wrocław, Poland (CET), remote