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Flexina - Online invoicing software
Accountants
100% free for accountants & bookkeepers

Your clients' invoices in your accounting software

Keep your tools and your workflow. Flexina automatically delivers your clients' sales and purchase invoices to Horus, WinBooks, Exact, Sage BOB, Yuki, Octopus… in UBL XML or PDF. No setup, no fees.

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✓ No subscription✓ No installation✓ Nothing changes for you

The Flexina (fox) and Peppol Box (rabbit) mascots delivering a stack of invoices to the accountant
100 %
free for accountants
Since 2008
invoicing is our craft
Peppol since 2021
long before the mandate
15+ accounting tools
compatible, your choice

We adapt to you, not the other way around

3 ways to retrieve your clients' invoices

Already using a retrieval platform? Perfect. If not, pick the method that suits you best. Either way, it's free and your clients don't change a thing.

01

Email Connector

Set up your software's import address (Horus, WinBooks, Exact, Sage BOB, Yuki, ClearFacts…). We send everything automatically in UBL XML or PDF.

02

Web portal

View all your clients from the accountant portal, download their sales and purchase invoices, filter by period and export in bulk. No installation needed.

03

Flexina Sync

Full automation. Our desktop app (Windows/Mac) syncs invoices straight into your software's folders, at whatever frequency you choose.

Your clients don't change anything, and neither do you. In UBL XML or even PDF.

Works with your accounting software

Every good accounting package imports invoices in UBL XML, Peppol or PDF. If yours supports import, it works — and you keep the software you already use.

HorusWinBooksExact OnlineSage BOBYukiOctopusWinAuditorExpert/MAdsolutClearFactsVenicePopsyWingsTop Account

Plus any software that supports UBL / Peppol / PDF import. Not sure? Just ask us →

How does it work? In 3 steps.

Set up automatic retrieval in just a few minutes.

1

Create your accountant portal

Free sign-up in a few minutes. No card, no commitment.

2

Your clients link to you

From their Flexina or Peppol Box interface, your clients connect to your firm in one click.

3

Receive their invoices

Choose your method and format (UBL XML or PDF). Sales and purchase invoices arrive automatically.

Peppol 2026: an opportunity

Guide your clients toward a compliant solution

With the Peppol mandate, your clients are looking for reliable solutions. We offer software built for them — with Belgian support included and clear pricing.

from €20/mo

Flexina Invoicing

Complete business management: quotes, orders, invoices, e-signature, reminders, bank reconciliation, CRM, scheduling…

Discover Flexina
from €5/mo

Peppol-Box

A simple, effective solution for sole traders and shopkeepers who want to send and receive Peppol e-invoices.

See Peppol-Box
from €10/mo

Peppol-Box Integration

For businesses with an existing ERP or software: API, XML sending, PDF-to-XML conversion.

See the integration

Support included, based in Belgium

Your clients call us directly. No tickets, no waiting, no extra charge — support is included in their licence.

Clear, fixed pricing

Prices that don't creep up, with support, maintenance and updates all included. No nasty surprises.

120% tax deduction

Reassure your clients: they qualify for a 120% tax deduction when they adopt an e-invoicing solution.

Why accountants choose Flexina

Invoicing specialists since 2008, Peppol live since 2021, UBL XML export for the past 5 years. We know e-invoicing inside out — and it's free for you.

Free for your firm

No subscription, no licence, no hidden fees. Flexina Sync is 100% free for accountants and bookkeepers.

We adapt to your tools

Keep your software and your way of working. We deliver invoices wherever you want, in whatever format you want.

Peppol & UBL compliant

Every invoice issued through Flexina or Peppol-Box meets the Peppol BIS 3.0 and UBL XML standards.

Data secured in Europe

Encrypted transfers, European hosting and GDPR compliance. Your data and your clients' data stay protected.

The key point

Your clients' support? That's on us.

A question, a snag, a step that needs explaining? Your clients call us directly, not you. Our Belgian team is reachable by phone, chat and email — and support is included in the licence price.

With Flexina and Peppol Box, your clients will never come to you with a technical issue about using our software. You save time, and they're taken care of.

✓ Belgian team, real people✓ Phone · chat · email✓ Included, no extra cost
The Flexina support team, shown as the fox mascot wearing a headset, handling your clients' technical questions

Peppol 2026 Solutions for Accountants and Their Clients

See how Flexina helps accountants guide their clients through Peppol e-invoicing with two tailored solutions (Flexina Invoicing and Peppol Box) plus a free, flexible retrieval system (Flexina Sync).

Peppol solutions for your clients

Which solutions does Flexina offer for the Peppol 2026 mandate?
Flexina offers two solutions connected to the Peppol network: Flexina Invoicing for complete business management (quotes, invoices, purchases, CRM, scheduling…) and Peppol Box, an affordable solution for those who mainly need to receive invoices and only occasionally issue B2B invoices.
What's the difference between Flexina Invoicing and Peppol-Box?
Flexina Invoicing is a complete business management package (quotes, invoices, CRM, scheduling). Peppol-Box is a simple, effective solution for sending and receiving Peppol invoices. For businesses with an existing ERP, Peppol-Box Integration enables integration via API, XML sending or PDF conversion.
Are these solutions suitable for small businesses?
Yes, our solutions are designed specifically to be affordable and suitable for businesses of every size, at accessible price points.
What is Flexina Sync?
Flexina Sync is our free system that lets accountants automatically retrieve all the invoices of clients running our solutions. It adapts to the way you work without forcing any changes on you.
Is Flexina Sync really free for accountants?
Yes, Flexina Sync is 100% free for accountants and bookkeepers. No subscription, no licence, no hidden fees.

Retrieval methods with Flexina Sync

What are the different ways to retrieve my clients' invoices?
Flexina Sync adapts to your workflow: delivery by email with a download link, integration with your existing platforms (Billtobox, Billit, Horus, Bob Demat…), access to the online download portal, or installing the Flexina Sync app for automatic synchronisation.
Can I keep using my current platform (Billtobox, Billit, etc.)?
Absolutely! Flexina will automatically send your clients' invoices to your usual platform's retrieval email address. You don't have to change your habits.
How does email delivery work?
You receive an email containing a download link. You can then choose the format that suits you (PDF or XML) for your clients' sales and purchase invoices.
Is the Flexina Sync app mandatory?
No, it's simply one option among others. If you prefer full automation, the app automatically synchronises invoices according to your preferred folders, formats and frequencies.

Compatibility and integration

Which accounting software is compatible?
Every good accounting package supports importing invoices in UBL XML, Peppol or PDF. Expert/M, WinAuditor, Horus, Adsolut, Octopus, WinBooks, Yuki, Venice, Sage BOB, Exact Online, ClearFacts, Popsy, Wings, Alpha, Top Account… If your software supports import, it works. You pick the format.
Do I have to switch from my current accounting software?
No! That's one of the big advantages of Flexina Sync: you keep working with the software you already use. We adapt to the way you work, not the other way around.
How is the link between my clients and my firm set up?
It's very simple: your clients activate the link to your accountant account directly from their Flexina or Peppol Box interface. After that, you choose how you'd like to receive their invoices.
Are the invoices Peppol-compliant?
Yes, every invoice issued through Flexina Invoicing or Peppol Box meets the Peppol and UBL XML standards, ensuring compliance with the 2026 mandate.

Practical questions

How do I get started with Flexina Sync?
Create your free accountant account, recommend our Peppol solutions to your clients (Flexina Invoicing or Peppol Box), then choose your preferred method for receiving their invoices. It really is that simple!
My clients are worried about the cost of the Peppol transition. What should I tell them?
Reassure them: Flexina offers solutions with clear, affordable pricing. On top of that, they qualify for a 120% tax deduction when they adopt an e-invoicing solution.
Is data security guaranteed?
Absolutely. Flexina uses advanced security protocols and complies with European standards. All transfers are encrypted and secure.
Can I test Flexina Sync before recommending it to my clients?
Of course! Create your free account and get in touch for a personalised demo. We'll show you how Flexina makes your day-to-day easier.

Get in touch to learn more about Flexina solutions

Since 2008, Flexina has supported thousands of Belgian businesses with their business management. Our experience and market knowledge let us offer solutions that genuinely fit. Free for your firm, affordable for your clients.

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Create your free accountant portal

Retrieve your clients' invoices however you like, without changing your tools. Free for your firm, affordable for your clients.

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