Quick post-mortem from the last six weeks of building a thing nobody asked for, because of a thing that happened to me that nobody warned me about.
Two months ago I finished a £6,400 branding gig for a Manchester agency. Six weeks of work, deliverables sent, invoice raised. Client went silent for four weeks then replied "we've decided not to proceed" and never paid. I went back to the contract looking for the clause that would let me reclaim the work. There wasn't one. The IP clause read "all work product becomes the property of the Client upon delivery." Upon delivery. Not upon payment. They legally owned the brand assets the second I sent the file.
That's what got me building. ShieldSign runs UK freelance contracts through Claude Sonnet 4 with a prompt tuned for UK contract law and IR35. Output is a fairness score, red flag clauses with explanations, and amendment suggestions you can paste back at the client. Free fairness check, £7 for the full report.
What I learned in three weeks
1. Contract analysis with LLMs is a much narrower problem than it looks from the outside. UK contract law has specific patterns, English-court enforceability is different from American contracts, IR35 is its own thing. Generic legal-AI tools miss this completely. Niche prompt = niche product = better answers.
2. Cost per analysis on Sonnet 4 with prompt caching sits at about £0.05. At a £7 price that's 99 percent margin on the unit, but the bottleneck is never unit margin. It's traffic, every time.
3. Pricing was the mistake I'm still recovering from. I started thinking subscriptions, then realised contract analysis is a job-to-be-done, not an ongoing relationship. People sign maybe four contracts a year. £7 per report is friction-free, monthly subscription is friction. Took me a week to admit this.
4. Patterns from the first 30 contracts run through it are bleaker than I expected. IP-on-delivery shows up in roughly four out of five UK freelance contracts. Uncapped indemnification in about two thirds. Non-competes that probably wouldn't survive a UK court in just over half. None of it is illegal. Most are five-minute fixes if the freelancer asks. They almost never ask.
5. Distribution is genuinely the hardest part. I built the funnel before I had any way of getting people to it. HVCO checklist, drip emails, retargeting tags, Stripe webhooks, the lot. It's a beautiful funnel with very little water in it. Working on that now.
Stack
Next.js 16, Vercel, Supabase, Stripe, Resend. Anonymous free check, magic-link auth for paying users, RLS on everything Supabase-side.
What I want from you
Not asking for upvotes or anything. If you're a UK freelancer or work with them, throw a contract through and tell me what's broken in the output. getshieldsign.com is the homepage, /free-checklist for the PDF. The £7 report is the only thing behind a paywall and it has a refund-if-you-find-a-clause-we-missed thing on it because I'd rather hear about misses than keep the £7.
Specific feedback I'd value:
- £7 vs free score split is the right place to draw the paid line, or wrong?
- The "free fairness check" wording, does that read as honest or weaselly?
- Anything in the prompt output that screams AI rather than reads like a human contracts lawyer wrote it.
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