Fair play for offering to build something for free in exchange for practice and a testimonial. That is a reasonable trade, but anyone thinking of taking it up should ask a few questions before handing over their lead data.
Questions worth asking before saying yes - Who owns it afterwards? Get it in writing that the business owner owns the app, the code and any accounts it runs on. If the builder moves on once the training finishes, you do not want your lead flow sitting in someone else's login.
- What does it cost to keep running? "Free to build" rarely means free to run. SMS gateways, hosting, AI API calls and automation platforms all have monthly fees. Ask for a rough figure per 100 leads so there are no surprises on the card statement.
- Where does the data live? Lead names, numbers and enquiry details are personal data under UK GDPR. If the app pushes that through third-party services, the business owner is the controller and needs to know which processors are involved and where the servers are. Most small firms handling customer data also need to be paying the ICO data protection fee, which starts at £40 a year, so check that is sorted.
- Who sees the leads during the build? If the developer has access to real enquiries while testing, a short confidentiality agreement is sensible. A one-page NDA is plenty for this.
A note on the stats The "391%" and "100x" figures come from US studies that get recycled a lot in sales marketing. The underlying point is sound, though: calling back inside a few minutes genuinely does win more work, particularly for trades, property, and anything quote-based. A text alert with a suggested script is a decent idea, as long as the human still does the call.
To the original poster, you would get more takers if you listed the tools you are building on and confirmed the business keeps full ownership. People on here are cautious with anything free, and rightly so.