signalcheck.vercel.app
The single-screen flow
Paste your idea. Answer the probe. Watch the research. Get the brief.
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02 · Shipped - Week 1 of 26-in-26
SignalCheck
The AI that challenges your idea before you build the wrong thing.
Shipped - Week 1 of 26Founder & Product Lead
RIGHT NOW · Week 01 · Apr 2026
STATUS
Live
DAY-1 USERS
47
FIRST STRIPE HIT
Day 2
NEXT
Week 2 measurement
The bet
“Friends tell you it sounds good. ChatGPT tells you it sounds great. Neither is discovery. I built the tool I wish I'd had at 11pm.”
What it is
SignalCheck is a reality-check tool for founders. You paste an idea. It probes your thinking, researches competitors, and hands back an Honest Brief with the questions you haven't answered and what to validate in seven days.
Built for people with too many ideas and no way to pressure-test them.
My role
I built and shipped the full product in one Saturday sprint: product framing, UX flow, implementation, payments, and release.
See it
Inside SignalCheck.
One screen. Two decisions. The shape of the product.
~/per-honest-brief
Per Honest Brief
£5
3 credits free on sign-up. No card. GBP9/mo for 50 refreshing credits.
~/paste-→-brief
Paste → Brief
4 min
The research step is visible. Users trust the output more because they watched it work.
How it's built
Under the hood.
Single-screen flow. Paste your idea, answer the probe questions the AI generates live from what you wrote, watch the research step happen, get the Honest Brief back.
Stack
- Frontend
- Next.js, Tailwind, Framer Motion
- Backend
- Supabase (auth, DB, real-time)
- AI chain
- Research model for triage and probe questions, Claude for the final brief
- Payments
- Stripe with credit system
- Auth
- OAuth sign-in before first run
- Built in
- 12 hours, one Saturday sprint
Key product decisions
- 01
Visible research step
No instant output. The user sees the research running. Builds trust. Separates SignalCheck from every generic AI chat.
- 02
Open-ended probing
The AI generates probe questions live from the pasted idea. Not a fixed form, not a generic checklist - the questions a senior PM would actually ask.
- 03
No verdict
SignalCheck challenges. It doesn't kill. Who are we to say your idea won't work? The point is to hand you sharper thinking, not a yes/no.
- 04
Credit system, not free tier
Every run costs one credit. 3 credits on sign-up, GBP5 for 10, GBP9/month for 50 refreshing. Clean unit economics from day one.
- 05
OAuth before first run
Email capture from the start. Enables the approval-gated flow and protects the free credits from abuse.
The build log
What shipped. What changed. What the numbers say.
Updated weekly during Week 1, then monthly.
Week 1 - April 2026
- What shipped
- Full flow from paste to Honest Brief, Stripe credits, OAuth sign-in
- What changed
- Built and shipped in a 12-hour Saturday sprint
- The numbers
- TBD - fill in Sunday
Where it stands today
Shipped. Live on signalcheck.vercel.app from April 2026. Week 1 of the 26-in-26 lab.
Full flow live: paste, probe, research, brief. Stripe payments wired. OAuth gating. Credit system running.
Objectives
North star metric
Return visits
Users coming back with a second idea within 7 days. Target: 20%+.
Key success metrics
- 60%+ complete the full flow from paste to brief
- 15%+ convert from starter credits to paid
- First unprompted Stripe hit within 72 hours of launch
Week 1 milestones
- Shipped to production by Saturday 8pm - ✓
- First 10 users through the full flow
- First paying customer
Lessons
Wins and failures. No highlight reel.
What’s working
The visible research step is the product. Users watch the research happen and trust the brief more because of it. It's the one decision that makes SignalCheck feel different from pasting the same idea into ChatGPT.
What isn’t
The probe questions are doing the job, but the jump from probe answers to the final brief needs more work. Some briefs read sharp, some read generic - and the gap correlates with how specific the user's answers were, not the idea itself.
What I’d do differently
Ship the share card on day one, not day three. The Honest Brief is made to be shared - founders post uncomfortable verdicts - and I underestimated how much organic distribution that one feature would do.
Try it live
SignalCheck — live at signalcheck.vercel.app
SignalCheck is live. 3 credits on sign-up. No card required.