About
Built by a freelancer who got burned. So you don't.
ShieldSign is a one-person side project that grew teeth after a single contract clause cost me £6,400 of unpaid work. This page is the story, who I am, and how the tool actually works under the hood.
The clause that cost me £6,400
Branding project for a Manchester agency. £6,400. Six weeks of work. Logo, brand guidelines, full identity rollout. Sent the deliverables, sent the invoice, then they went silent. Two weeks later I'm chasing, three weeks I'm threatening small claims, four weeks they reply with “we've decided not to proceed” and I never see the money.
I went back to the contract looking for the clause that would let me pull the work back. There wasn't one. The IP clause read “all work product becomes the property of the Client upon delivery.”
Upon. Delivery. Not upon payment.
I'd handed over £6,400 of brand assets and the contract said they owned the lot the second I sent the file. Whether they paid or not. They were already running the new logo on their website by the time I noticed.
That sent me on a tear. I started feeding every UK freelance contract I could get my hands on through Claude with a custom prompt, looking for the same trap. After about 120 contracts (design, dev, copy, consulting), the same five clauses keep showing up in roughly 80% of them. None are illegal. Most are negotiable in a five-minute conversation. Almost nobody asks.
ShieldSign is the tool I wish I'd had three months ago.
Founder
Lee Stephenson
UK based. Builds tools that solve problems he's personally hit. Previously: PDFico (browser-based PDF toolkit). Now: ShieldSign.
Honest disclosure: I don't do social media. No Twitter, no LinkedIn, no TikTok. Direct email is the fastest way to reach me, usually within 24h.
What ShieldSign actually does
You upload (or paste) a UK freelance contract. The tool runs it through Claude Sonnet 4 with a prompt tuned for UK contract law and IR35 implications. You get back a Fairness Score, a list of red flag clauses with explanations, rewrite suggestions you can paste at the client, and a plain-English summary.
Free tier shows the score and clause breakdown. £7 unlocks the full report with rewrite language and a downloadable PDF. £39/month for unlimited if you review contracts often. £129/month with team seats and bulk upload for agencies.
The model is good at flagging the patterns. It is not a lawyer. For high-value contracts, take the output to a real solicitor.
How your contract is handled
Never stored
Contracts are sent to Claude for analysis, then the request is dropped. No copies on our servers. No training data feedback loop.
Encryption in transit
TLS 1.3 to our servers, then Anthropic's end-to-end encrypted API. We never see your contract on disk or in cleartext logs.
Paste only sensitive bits
Use the Paste text option instead of upload if you want to share a single clause without sending the whole contract. Same analysis, less data.
No client names
We don't need them. Redact your client's name and any commercial figures you don't want analysed before pasting. The clause language is what matters.
Under the hood
Next.js 16 on Vercel. Supabase for auth and analytics events. Stripe for one-time and subscription payments. Resend for transactional email. Claude Sonnet 4 for the analysis itself, with prompt caching to keep the cost around £0.04 per contract.
Built solo over three weeks of evenings and weekends, then iterated based on every honest critique I could pull out of Reddit, AccountingWeb and DM threads. Some of the most useful product feedback came from u/Substantial_Car_8259 who asked for a paste-text option, which is the reason that tab exists.
Honest answers to questions you should be asking
Why no LinkedIn or Twitter? Doesn't that look sketchy?
It does look sketchy and I've been told as much. I don't do social media because I lose hours to it. The compromise is this page, a real email, and a Reddit handle where you can read every post and reply I've made. Take that signal or don't.
Are you a lawyer?
No. I'm a freelancer who got burned and built a tool. The model has read a great deal of UK contract law and is good at pattern matching. It is not a substitute for legal advice on a meaningful contract. Take big ones to a solicitor.
Will you read my contract?
The model will. I won't. The processing happens in real time and the request is discarded. I have no admin view that lets me read uploaded contracts and I built it that way deliberately.
What happens if I disagree with the model?
Email me with the contract redacted and the clause you think it got wrong. If you're right I'll fix the prompt. The 120 contracts I've fed it so far improved the output every single time someone pushed back.
Try it on a contract you actually have
Free fairness check. No card. No signup tricks. The tool either earns your trust in 30 seconds or it doesn't.
ShieldSign is a sole-trader project by Lee Stephenson, registered for UK VAT when revenue thresholds require it. Questions, complaints, feedback:lee@getshieldsign.com