I'm Jelena, a freelance backend developer in Novi Sad. 20 years of PHP and MySQL: complete custom CRM systems, payment and accounting integrations, and the legacy systems other people are afraid to touch.
Most businesses end up with a CRM here, a spreadsheet there, and an accountant asking why the two don't match. I build one system that carries a customer all the way through — and closes the loop back into the books.
One record per customer: people, addresses, notes, files, and every invoice and payment attached to it.
Enquiries through stages to won or lost, with owners, follow-up dates and nothing sitting untouched.
Line items, discounts, tax rules and versioning — a quote becomes an order becomes an invoice without retyping.
Your document layout, your numbering, generated server-side. Recurring invoices run on a schedule.
Mandates, subscriptions and one-off charges via GoCardless or Stripe, with webhook status written back automatically.
Who owes what and for how long, automatic reminders, and failed payments that surface instead of disappearing.
Revenue by period, product or salesperson, commission calculations, and exports finance can actually use.
Who can see what, who changed what and when. Sales sees their accounts; the office sees the money.
| Invoice | Client | Method | Due | Status |
|---|---|---|---|---|
| INV-20418 | Harlow Fleet Services | Direct debit | 02 Jul | collected |
| INV-20419 | Bramley & Co | Direct debit | 04 Jul | submitted |
| INV-20420 | Northgate Training Ltd | Bank transfer | 09 Jul | overdue 11d |
| INV-20421 | Selby Motor Group | Card | 12 Jul | collected |
| INV-20422 | Wren Insurance Brokers | Direct debit | 15 Jul | retry 1 of 3 |
Whether it's a system from scratch or the missing half of the one you already have — enquiries in, money out, and reports that agree with the bank.
Talk about your CRMNot websites in general. The part that has to work on a Monday morning when the invoices are due.
Off-the-shelf software makes you work its way. I build the admin panel your business already runs on — and the parts of it nobody sells ready-made.
Two systems that need to agree with each other. Money collected has to match money recorded — built so failures are visible, not silent.
Inherited a codebase nobody wants to open? I take it over, stabilise it, and keep it running while we improve it — no rewrite-from-scratch theatre.
Not launches. Things I've kept alive for years.
A commercial vehicle sales platform, and mostly a place where other people's systems have to agree. Vehicle data comes from the DVLA, stock goes out to AutoTrader, customers go to Mailchimp, and invoices move proforma → on hold → issued with a PDF generated at every step. I built that workflow, the contact management and the 360° viewer — then moved the whole thing to a new server without losing a listing.
An admin panel that pulls customers, bank mandates, and subscriptions straight from the GoCardless API, with cursor pagination and cached responses — so the office stopped logging into three places to answer one question.
Once a year the whole book of policies has to be repriced against the rate tables that were in force, quoted as a PDF, and reissued. It runs in chunks so it fits in memory, applies tax exactly once, and reports the policies it could not price instead of stopping at the first one.
A paid library of professional handbooks. Registration with email verification, admin-approved accounts, three purchase tiers, and protected in-browser reading — watermarked, no downloads. The content is the product, so the access control had to be the real work.
Most studios are built around design and frontend. Then a client asks for a payment integration, a members' area, or a system that has to talk to their accountant — and there's nobody to hand it to. That's the call I'd like to be on the other end of.
Your client never has to know I exist. Your process, your project manager, your invoice. I'm comfortable staying out of the room.
Registered in Serbia, invoicing in GBP or EUR. NDAs and contractor agreements are routine, not an obstacle.
Your repo, your conventions, your deployment. I don't arrive with opinions about your stack or a proposal to rewrite it.
One integration when you're stuck, or the backend you subcontract every time. Both work.
Most of what I do starts in someone else's codebase. I learn how it works before I change it, and I don't propose a rewrite to avoid understanding it.
No debug output left in the wild, no commented-out experiments, no half-finished branches. What goes live is what I'd want to inherit.
No account managers, no handoffs, no team you never meet. You explain the problem once, to the person who fixes it.
Based in Novi Sad, working mostly with UK and EU clients. Overlapping working day, replies within a day, usually sooner.
Manje sajtove, prezentacije i webshopove za klijente iz Srbije radim direktno — pogledajte srpsku stranicu.
Tell me what the system is supposed to do and what it's doing instead. I'll tell you honestly whether I'm the right person for it.
hello@jelena.dev