I'm Jelena, a freelance backend developer in Novi Sad. I've been working with PHP and MySQL for 20 years, mostly building and maintaining CRM systems, payment collection, invoicing, reports and various integrations.
I work on existing systems and new projects alike — from a single feature to a complete business platform.
A CRM doesn't have to be just a place to store customer data. It can connect sales, invoicing, collection and reporting so you don't have to enter the same information in several different places.
I can build a complete system or add just the part you're missing — from first enquiry to collected invoice.
All client information in one place — people, addresses, notes, documents, invoices and payments.
From first enquiry to completion. Every item has a stage, an owner and a next step.
A quote can become an order, then an invoice, without re-entering the same data.
Invoices following your rules, with your layout and numbering. PDF documents are generated automatically.
Integration with services like GoCardless and Stripe, including subscriptions, mandates and one-off charges.
Overview of overdue balances and automated reminders. Failed collections stay visible until resolved.
Revenue, sales, commission and debt data, with exports ready for accounting.
Access control by user role and a change log — who changed what and when.
| 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 |
A complete system from scratch or just the feature you're currently missing.
Talk about your CRMBeyond CRM systems, I work on business applications, integrations and existing systems that need maintenance or further development.
If off-the-shelf software doesn't fit the way you work, I can build a system tailored to your processes.
Connecting different systems so data and statuses flow automatically from one to another.
If you have an application built by someone else, I can take over maintenance and ongoing development.
I don't just pick projects that look good in a portfolio. What matters more to me are systems that are used every day and that I've been maintaining and improving for years.
Commercial vehicle sales in the UK. The system connects DVLA data, AutoTrader listings, Mailchimp communications and invoicing, including PDF generation.
I built the complete workflow and admin panel, then migrated the system to a new server without losing any data.
An admin panel connecting clients, mandates and subscriptions with GoCardless, linked to Xero.
Previously, checking this data required logging into several different systems.
Automatic processing of a large volume of policies: repricing against current rate tables, generating PDF documents and reissuing.
Processing runs in batches so the system can handle a large number of records without overloading the server.
A platform for selling professional handbooks with user accounts, different access tiers and protected content delivery.
Alongside long-term work on business systems, I've also worked on projects that involved complete development — from the database and backend to admin, user accounts and integrations.
The design and frontend are done, and then comes the need for user accounts, payment collection, admin, API integration or connecting to another system.
That's where I can step in and take over the backend side of the project.
I can work entirely behind the scenes, following your process and the way you communicate with your client.
I have a company registered in Serbia and can work under contract, NDA and regular invoicing.
I can work in your existing repository, following your conventions and deployment process. I don't insist on changing the existing system just because I would have built it differently.
We can work on a single task, integration or fix, or we can arrange ongoing backend support.
A large part of the work starts in code someone else has already written. I want to understand how the system works first, and only then change what needs changing.
I aim to leave behind code that will be understandable to the next person who works on the project.
You communicate directly with the person working on your project. No passing problems through several layers.
I work with clients from Serbia, the UK and the EU, with overlapping working hours and regular communication.
Za klijente iz Srbije dostupna je i srpska verzija stranice — pogledajte srpsku stranicu.
Send me a few details about what you want to build or what isn't working the way it should.
I'll look at the problem and tell you honestly whether I can help.
alba.avis@gmail.com
