Case studySaaSSMEsAI
Case study: Izi-Devis, voice-driven quotes and invoices for tradespeople
5 min read
Izi-Devis is quoting and invoicing software for French building tradespeople, designed, built and run by LPR Studio itself. Tradespeople dictate a quote, review it, send it, then turn it into an invoice. The project started in April 2026; the software is live and open to the public at izi-devis.net, and it ships improvements every week.
It is not a client project: it is our own product. That is exactly why we can show all of it, from the original problem to the software in production.
The problem
Plumbers, electricians, painters, masons, tilers: most work alone or in small teams. Days are spent on site, and paperwork waits until evening. Quotes, deposit invoices, chasing late payments, mandatory legal mentions: hours taken from family time.
Invoicing software exists, but it is built for an office: long forms, typed on a keyboard, in front of a computer. A tradesperson usually prepares a quote in the van, phone in hand, right after seeing the job.
The need fit in one sentence: produce a clean, compliant quote as fast as you can describe the job out loud.
What we built
Voice input. The tradesperson describes the work the way they would on the phone. AI turns it into structured quote lines (description, quantity, price), which the user reviews and corrects before anything goes out. Nothing is sent without their approval, and typing is always available.
The full cycle, from quote to payment.
- quotes with online approval by the customer;
- deposit, progress and final invoices, and credit notes;
- unpaid invoice tracking and reminders;
- PDFs with VAT and the legal mentions French law requires;
- job reports with before and after photos, and a map of job sites.
Bridges to existing tools. Nobody starts from scratch: an accounting export in the French FEC format for the accountant, import from another quoting tool, a browser extension to capture supplier prices, and a connector to manage quotes from an AI assistant. Our guide to adding AI to a business application explains why the AI stays a helper, never the decision maker.
An installable web app. Izi-Devis runs in the browser and installs on the phone's home screen like an app (a PWA). Our comparison of web apps, PWAs and native apps explains that choice.
Hosting and operations. The application is hosted in Europe, monitored, backed up and updated continuously.
The result
- Software in production, open to every tradesperson, with a free plan (5 quotes, no card needed) and a Pro subscription whose price is published on izi-devis.net.
- A living product: new versions have shipped every week since day one, driven by feedback from the tradespeople who use it.
- Ready for e-invoicing: the Factur-X format, which the French reform is progressively making mandatory, is live, and the connection to an approved platform is in testing. The details are in our guide to the French e-invoicing mandate.
Usage metrics stay internal: we do not publish figures you cannot verify.
What this means for your project
Izi-Devis is not custom software: it is a product published for every tradesperson, which makes it far cheaper for each of them. But it was built by the same team, with the same method, as the applications we build for clients.
- Start from the field. The interface was designed for people who are not software experts, on a phone, between two jobs.
- Use AI where it saves time, and leave the decision to a human.
- Ship, then keep improving. Useful software does not stop at delivery: it lives in production. Our guide to the cost of building a SaaS platform covers what running it really involves.
If a need in your business looks like this one, we build a free visual prototype, presented on a video call within 5 working days: you see the tool before you commit to anything.