Sell more of what you already do
Clear pages, forms that work, and payment-connected flows, so buying is obvious and nothing gets lost between first interest and signed work.
Custom software and web development studio
Open for new projectsCustom software and websites, built like your business depends on them.
I'm Fabian Janiszewski, and I design and build every project myself, for businesses that want it done properly the first time. From a sharp marketing site to a full internal system: one builder, senior work, anywhere in the world.
You work directly with Fabian. No salesperson, no PM, no handoff in between.
followupos.dev
Selected work
FollowUpOSOwned product, in production
- Founder-led studio based in Spain
- Local Spain and global clients
- FollowUpOS and DealSharp, owned products
- Presupuestos OS, live Spanish demo
- Direct owner-builder, not an agency
- Delivered in English and Spanish
File 01, the diagnosis
Most businesses don't have a tool problem. They have a system problem.
You've already bought the tools. The leak is in between them, in the handoffs, the follow-ups, the spreadsheet only one person understands. Here's what it looks like in the wild, and what closes it.
01Leads go quiet because nobody followed up
What it costs
Every forgotten follow-up is revenue you already paid to earn, the ad spend, the calls, the proposal, gone silent.
What closes it
A follow-up system with reminders, drafts, and pipeline memory. This exact leak is why I built FollowUpOS.
02The business runs on one heroic spreadsheet
What it costs
One broken formula, one person on holiday, and operations stall. Spreadsheets don't scale, they accumulate risk.
What closes it
An internal tool with real structure: roles, history, validation. The spreadsheet's job, minus the fragility.
03The CRM exists, but nobody uses it
What it costs
You're paying for software that holds stale data while the real pipeline lives in someone's head.
What closes it
Either a workflow layer that makes the CRM worth opening, or a leaner system shaped around how your team actually works.
04No one can answer “how are we actually doing?”
What it costs
Decisions run on gut feel and last month's invoices. Problems show up in the numbers months after they started in the workflow.
What closes it
A business dashboard pulling from your real tools, pipeline, cash, delivery, on one screen you'll check daily.
05The website looks dated and says the wrong thing
What it costs
People judge before they get in touch, so your best work never gets a fair hearing and the quote request goes to someone else.
What closes it
A conversion website wired into a workflow: visitor, enquiry, follow-up, client. Not a brochure.
06The MVP stays an idea because nobody builds it
What it costs
Every month it sits in your notes app, someone else gets closer to shipping it first.
What closes it
An OpsBuild Sprint: scope it, design it, and build the first working version you can put in front of real users.
Diagnosed · Designed · Built
“Every messy process eventually becomes messy numbers. I've seen it from the bookkeeping side, that's why I build from the workflow up, not from the feature list down.”
File 02, the catalog
What I build
Eight kinds of systems, one rule: it has to get used. If it won't survive contact with a real Tuesday, it doesn't ship.
#SystemWhat it isForOutcome
- 01
Websites & conversion funnels
A website that's the front door of a workflow: visitor, enquiry, follow-up, client. Not a brochure.
For
Businesses whose site looks fine but converts nothing
Outcome
Visitors enter a system, not a void
- 02
Internal dashboards
Your pipeline, cash, and operations on one screen, fed by the tools you already use.
For
Operators flying blind between five tabs
Outcome
One screen, real numbers, checked every morning
- 03
SaaS MVPs
Your product idea, built to the first version real users can touch, scoped to learn, not to impress investors with a slide.
For
Founders with an idea and no build partner
Outcome
A working product in users' hands instead of a pitch deck
- 04
Follow-up & CRM systems
Pipelines that run on process instead of memory, reminders, drafts, and a record of every relationship.
For
Sales-driven businesses losing deals to silence
Outcome
No lead goes cold because someone forgot
- 05
Client portals
One place where clients see status, files, and next steps, instead of asking by email.
For
Agencies and service businesses with anxious inboxes
Outcome
Fewer status-update emails, calmer clients
- 06
E-commerce, booking & payments
Checkout, subscriptions, invoices and webhooks wired into your own system, so money and records stay in sync on their own.
For
Businesses chasing payments and bookings by hand
Outcome
Payments, bookings and records reconcile themselves
- 07
Workflow tools
Small, custom software that replaces the duct tape: the form, the tracker, the calculator your business actually needs.
For
Operators with one painful process everyone hates
Outcome
The ugly manual step becomes a button
- 08
Automation & AI workflows
Your tools finally talking to each other, and AI where it earns its keep: drafting, sorting, summarizing inside your process, with humans on the decisions.
For
Teams gluing tools together by hand
Outcome
Hours back every week, without betting the business on a black box
I use AI-assisted development internally, for speed and cleaner code. Every technical decision and every line that ships is reviewed and owned by a human.
Outcomes
What changes when the system actually fits the business
01 02 Operate with less friction
One place to see the work. Dashboards, client portals, and internal tools that replace scattered spreadsheets and long email threads.
03 Launch sooner than you planned
Scope is phased and shipped in short cycles, so a first useful version is live and in real use while the rest is still being built.
04 Cut the manual work out of the day
Repetitive steps get handled by the system instead of by you and your team: follow-ups, quotes, handoffs, data entry.
05 Look like the company you already are
A site and a product experience that match the quality of your actual work, so you are never explaining away an outdated website in a first meeting.
File 03, where to start
Start with one focused build, not a twelve-month plan.
Start here
OpsBuild Sprint
Most projects go wrong before a single line of code is written. The OpsBuild Sprint fixes that order. I look at how your business actually runs, decide what deserves to be built first, and ship a working piece of it with the scope agreed from day one. Weeks, not months.
- A proper look at the workflow you actually run, not the one written down on paper.
- A defined first phase with clear scope, so you know exactly what you are getting.
- A working build you can put in front of real customers or your own team.
- Documentation and a straight answer on what to build next, or whether you need anything else at all.
01
A website that sells
A fast, clear site built to turn visitors into real enquiries. Written, designed, and built by the person you talk to.
02
Website plus business workflow
The public site connected to what happens after the click: forms, bookings, payments, follow-up, and the admin side behind it.
03
Custom app, dashboard, or MVP
Internal tools, client portals, dashboards, and scoped SaaS builds. Software shaped around how your business really works.
Not sure which one fits? Send me the problem in plain words and I will tell you what the right first phase is, even if it turns out smaller than you expected.
File 04, the OpsBuild Method
I don't build apps first. I map the leak first.
Seven steps, in order, every time. The order is the method, building before diagnosing is how businesses end up with one more tool nobody uses.
Step 01
Diagnose the leak
Find where the business actually loses time, leads, or clarity, not where it's most fun to build.
Step 02
Map the workflow
Who does what, when, with which tool. The real process, including the embarrassing parts.
Step 03
Design the system
The smallest system that closes the leak. Architecture, data, screens. Boring on purpose.
Step 04
Build the first working version
Working software early, something you can click, break, and react to. Not mockups.
Step 05
Connect data and tools
Your CRM, sheets, inbox, and calendar talking to each other. The system meets reality.
Step 06
Polish the experience
If it isn't pleasant to use, it won't be used. This is where most internal tools die, not here.
Step 07
Launch, test, improve
Ship it, watch real usage, and fix whatever reality disagrees with. Handoff comes with documentation and all the access.
opsbuild.flow
Without thisWork arrives in four places and depends on somebody remembering.
“The best system is usually the boring one people use every day.”
File 05, work and proof
Proof you can open and click through.
No case study theatre and no invented numbers. These are products and pages I designed, wrote and built myself, so you can judge the build quality, the design and the way the copy is set up to convert before you hire me.
Owned product, in production
FollowUpOS
My own follow-up system for people who lose deals in the gaps. A full product build: data model, app interface, background jobs and the marketing site around it.
Owned product, real estate SaaSDealSharp
A real estate SaaS built end to end. Heavier data, filtering and dashboard work, the kind of interface a business sits in all day.
Private pilot, sample dataFarmaPanel
Pharmacy software that reads a pharmacy's own management data and turns it into a clear panel: what expires, what is not rotating, where margin is lost. Read only, no patient data, and it does not touch the pharmacy's existing system.
Spanish quoting system demo Presupuestos OS
A quoting system built around how Spanish businesses actually quote. It shows how a repetitive back office job turns into a fast, clear internal tool.
Designed, written and built by Fabian This website
Structure, copy, design, code, bilingual setup and the live tools running on it. If you like how this site works, that is the same standard you get.
Live demos
Proof you can touch, not just promises
Real systems running on sample data. Open them on your phone and see the kind of system I build for real businesses.
Sample data. No real company or client.
Fabian Janiszewski
Extremadura, España
File 06, the operator behind it
You work with the person who actually builds it.
In most studios, the person who sells you the project never opens the code. Here, that is the same person. My background sits across business operations, financial clarity, and software delivery, so I understand the process behind your business before I design a single screen, and I use AI-assisted development to move faster without handing quality to someone junior. On bigger builds I phase the scope and bring in specialists when it genuinely helps.
- Senior attention on every build, with no agency layers between you and the work.
- One person responsible from first idea to delivery, so nothing is lost in a handoff.
- I learn the business process behind the screen, not only the screen itself.
- Honest scope, and an honest no when custom software is not the right answer.
The route so far
Origin
Bookkeeping & financial clarity
Where broken workflows show up as broken numbers.
Then
Operations & client systems
Running the processes, not just recording them.
The turn
First internal tools
Building what the spreadsheets couldn't hold.
Product
FollowUpOS
A real follow-up problem, turned into a SaaS.
Product
DealSharp
Real-estate finance experience, turned into a platform.
Now
OpsByFabian
The studio that builds these systems for others.
Fit check
Who I work best with, and who I don't
Best fit
- Businesses in Spain that need a real website, booking, quoting or admin system, not another patch on the last one.
- Service businesses and founders losing work to messy follow-up spread across inboxes and spreadsheets.
- Small teams that need a dashboard, client portal, payment flow or internal tool built around how they actually work.
- Founders with a clear SaaS MVP scope and a real budget, ready to ship a first version and learn from it.
- Owners who want one responsible builder from the first call to launch, not a chain of account managers.
Not a fit
- You are shopping on price alone, with no defined scope.
- You expect guaranteed leads, rankings or revenue. No one can honestly promise that.
- You want AI added purely so you can say the product has it.
- You expect unlimited work, with no timeline and no defined finish line.
File 07, The Business Leak Scorecard
Find the leak before you fund it.
Seven questions, honest output: where your workflow is most likely bleeding time, leads, or clarity, and which system closes it. Everything runs in your browser. Nothing is sent anywhere.
Inquiries, calls, DMs, anything that could become business.
Roughly, per client or project.
The honest number, not the aspirational one.
CRM, sheets, chat, email, project boards…
Mostly automatedAll by hand
Your leak profile
Leak score
65/100
Value at risk in follow-ups
$4,330/month
Missed follow-ups × average deal value, assuming roughly 1 in 10 followed-up leads closes. Rough math, but so is losing them.
Your biggest leak
Revenue leak, paid-for leads going cold in the gap between “interested” and “followed up.”
The system I'd build first
A follow-up system: reminders, drafts, and pipeline memory. The FollowUpOS problem, solved for your workflow.
This is a directional diagnosis, not an audit. The real one happens on a call, bring these numbers.
Extremadura · Madrid · Castilla-La Mancha
For local businesses: more clients, less manual work, better control
I help businesses across Extremadura, Madrid and Castilla-La Mancha capture clients, stop losing follow-ups, and run their operation on simple digital systems. It starts with an operational diagnostic: I map how the work actually runs, find where hours and money leak, and leave you a clear plan. Remote by default, on-site when a visit genuinely earns its place, on request with a week of notice.
Extremadura · Madrid · Castilla-La Mancha
- Websites that capture clients
- CRM and WhatsApp follow-up
- Dashboards: sales, margins, stock
- B2B portals and internal tools
- Practical AI for teams
- Training for owners and staff
Reviewed guides
Practical systems for specific operating problems
A small, manually reviewed library connected to real demos and services.
Let's build the system your business is missing.
Start with an OpsBuild Sprint: a scoped first build with a clear plan, defined deliverables, and something working you can actually use. If you are not sure what you need yet, describe the problem and I will tell you what I would build and why.
You get a personal reply from Fabian within 1 to 2 working days, an honest assessment of whether this is the right fit, and no hard sell.