- Builds
- SaaS with payments
SaaS with payments
Ship a small paid SaaS: sign-up, a simple product surface, and UK card billing — with a clear monthly £ bill at launch, ~100 users, and ~1,000 users.
For: UK/EU indie founder shipping a subscription SaaS (login, database, Stripe billing, hosting, transactional email)
The stack
DATAAUTHSupabaseAuth + Postgres in one project; strong free tierFree → £18.72
- Layer
- Auth + database
- Plan
- Free → Pro
- What it does here
- Auth + Postgres in one project; strong free tier
- Note
- Free pauses after 1 week inactivity; Pro from $25/mo
PAYStripe (UK)Card + Billing fees published in GBPNo platform fee + % fees
- Layer
- Payments
- Plan
- Pay as you go
- What it does here
- Card + Billing fees published in GBP
- Note
- 1.5% + 20p (standard UK cards) + 0.7% Billing
HOSTVercelCommon Next.js hostFree → £14.98
- Layer
- Hosting
- Plan
- Hobby → Pro
- What it does here
- Common Next.js host
- Note
- Hobby is non-commercial — commercial launch may need Pro day one
MAILResend3,000 emails/mo free (vs Postmark’s 100)Free → £14.98
- Layer
- Transactional email
- Plan
- Free → Pro
- What it does here
- 3,000 emails/mo free (vs Postmark’s 100)
- Note
- Free: 3,000/mo + 100/day; Pro required by ~1k users under this build
BUILDLovableScaffold UI / frontend fasterFree → £22 (annual £19/mo)
- Layer
- Optional AI builder
- Plan
- Free → Pro
- What it does here
- Scaffold UI / frontend faster
- Note
- Build tooling, not runtime; GBP on pricing page (UK); no FX
OPSGitHubDependabot + secret scanningFree
- Layer
- Monitoring and security
- Plan
- Free
- What it does here
- Dependabot + secret scanning
- Note
- Secret scanning + push protection free on public repos; private Secret Protection price not found
Steps
Scaffold
Start a Next.js app (optional: generate the UI shell in Lovable, then sync to GitHub).
Done when the app runs locally and is in a repo.
Create Supabase
New project; enable Email + OAuth; add
profiles/ tenancy tables; turn on RLS.Done when you can sign up and see a row in your tables.
Wire app auth
Supabase Auth (SSR cookies or client SDK); lock dashboard routes.
Done when logged-out users can’t hit the product.
Set up Stripe UK
Products + Prices in £; Customer Portal; Checkout or Elements; webhook on Vercel for
checkout.session.completed,invoice.paid,customer.subscription.*.Done when a test-mode checkout creates a subscription.
Map entitlements
Webhook upserts Stripe customer / subscription status into Supabase.
Done when paid vs unpaid users see the right UI.
Deploy
Vercel; set
SUPABASE_*,STRIPE_*,RESEND_*; custom domain + HTTPS.Done when production URL signs in and takes a test payment.
Transactional email
Verify your domain on Resend (SPF/DKIM/DMARC); send receipts from your domain.
Done when a real inbox gets a branded message.
Harden
Review RLS; verify Stripe webhook signatures; spend caps / alerts on Supabase and Vercel.
Done when secrets aren’t in the client and webhooks reject bad signatures.
Launch checklist
Privacy policy, terms, Stripe Tax / VAT approach (not priced here), Billing Smart Retries for failed payments.
Watch out for
- Vercel Hobby is non-commercial. A real paid SaaS may need Pro (£14.98/seat) from day one — don’t plan a commercial launch on Hobby.
- Stripe fees dominate at scale. At ~1,000 users / £20 ARPU, Stripe alone is ~£640/mo vs ~£49 platform subscriptions.
- Supabase Free pauses after 1 week of inactivity — fine for demos, bad for prod. Upgrade to Pro (£18.72) before you rely on it.
- Resend Free caps at 100 emails/day — onboarding bursts or password-reset spikes can fail; Pro is £14.98.
- Supabase Free: 500 MB DB / 5 GB egress — easy to outgrow.
- Card mix: totals assume 100% standard UK cards (1.5% + 20p). Premium (2.8% + 20p) or international cards raise the bill.
- VAT on US vendor invoices may apply for UK buyers — not included in these totals.
- Disputes, Radar, Tax and other Stripe line items are not in the stage totals.
- Desk-costed only — egress, deliverability, and cold starts are not measured yet. Next step: a hands-on 30-day run.
What it costs each month
Assumptions: £20/month per paying user; 100% standard UK cards; Stripe Billing pay-as-you-go 0.7%; ~4 transactional emails per paying user / month; VAT on vendor SaaS bills excluded (USD vendors typically quote ex-VAT and add tax by billing address — Vercel/Supabase state this; treat others as unknown until checked).
| Stage | Platform (no Lovable; Resend Free at (a)/(b), Resend Pro at (c)) | Stripe fees | Total | + Lovable Pro |
|---|---|---|---|---|
| (a) Launch (0 users, free tiers) | £0.00 | £0.00 | £0.00 | £22.00 |
| (b) ~100 paying users | £33.70 | £64.00 | £97.70 | £119.70 |
| (c) ~1,000 paying users | £48.68 | £640.00 | £688.68 | £710.68 |
Platform at (b) = Supabase Pro £18.72 + Vercel Pro £14.98 (= £33.70).
Platform at (c) = Supabase Pro £18.72 + Vercel Pro £14.98 + Resend Pro £14.98 (= £48.68).
Source for stage (c) Resend Pro correction: Resend pricing and Stackguide desk research (checked 2026-10-16). Confidence: verified (arithmetic + Resend Free caps).
Also know:
- If commercial hosting forces Vercel Pro at launch: (a) ≈ £14.98/mo before any Stripe volume.
- At ~1k users Resend Pro (£14.98) is required: 4,000 emails/mo (4 × 1,000 users) exceeds Free’s 3,000/mo and ~100/day caps. It is already included in (c).
- Effective Stripe take-rate at £20 ARPU (standard UK card + Billing): 3.2% of GMV → £0.64 per £20 charge.
- Stripe fees dominate the bill at scale — not the SaaS subscriptions.
What the totals leave out
- Fixed (roughly): Supabase Pro, Vercel Pro, Resend Pro — converted from USD at 0.7489. Optional Lovable Pro is £22/mo billed monthly (or £19/mo billed annually) in GBP on the pricing page — no FX. VAT on Lovable: unknown (page silent).
- Variable: Stripe card + Billing % (and any usage overages on DB/hosting/email).
- Free today that breaks later: Vercel Hobby (commercial policy), Supabase Free (pause + size), Resend Free (3,000/mo and 100/day caps — breaks by ~1k users under this build’s email assumption).
- Your price changes the maths: stage totals assume £20/user/month. Recompute Stripe fees if your ARPU differs.
Disclosures
No sponsored or affiliate placements in this build. Tools were chosen in Stackguide desk research for fit and published pricing clarity.
Alternatives
| Role | Alternative |
|---|---|
| Auth + database | Neon (Postgres) + Clerk (auth) |
| Hosting | Netlify |
| Transactional email | Postmark |
No second PSP was priced; Stripe UK is the payments default for this build.
Sources
FX used for USD tools: 1 USD = 0.7489 GBP (Bank of England reference rate, 16 Oct 2026). Source: https://www.bankofengland.co.uk/boeapps/database/_iadb-fromshowcolumns.asp?csv.x=yes&Datefrom=12/Oct/2026&Dateto=20/Oct/2026&SeriesCodes=XUDLUSS&CSVF=TN&UsingCodes=Y&VPD=Y&VFD=N (checked 2026-10-23). Confidence: verified (Bank of England series XUDLUSS). Stripe UK fees are already GBP — not converted.
Priced facts and stage totals: Source: Stackguide desk research from the vendor pages below (checked 2026-10-16), including a second check of Resend Pro and Lovable GBP pricing. Confidence: desk-costed. Excluded: VAT on vendor SaaS bills, disputes/Radar/Tax, domains/DNS/OAuth fees, usage overages beyond stage assumptions.
Primary vendor pages (all checked 2026-10-16):
| Vendor | URL |
|---|---|
| Supabase | https://supabase.com/pricing |
| Neon | https://neon.tech/pricing |
| Clerk | https://clerk.com/pricing |
| Stripe Payments UK | https://stripe.com/gb/pricing |
| Stripe Billing UK | https://stripe.com/gb/billing/pricing |
| Vercel | https://vercel.com/pricing |
| Netlify | https://www.netlify.com/pricing/ |
| Resend | https://resend.com/pricing |
| Postmark | https://postmarkapp.com/pricing |
| Lovable | https://lovable.dev/pricing (primary, browser-verified GBP, checked 2026-10-16) · docs https://docs.lovable.dev/introduction/subscription-plans (secondary; older USD figures superseded) |
| FX | https://www.bankofengland.co.uk/boeapps/database/_iadb-fromshowcolumns.asp?csv.x=yes&Datefrom=12/Oct/2026&Dateto=20/Oct/2026&SeriesCodes=XUDLUSS&CSVF=TN&UsingCodes=Y&VPD=Y&VFD=N |
Change log
| Date | Change | Source |
|---|---|---|
| 2026-10-16 | First live desk-costed build | Stackguide desk research |
| 2026-10-16 | Citation pass (inline sources + confidence) | Editorial update |
| 2026-10-16 | Stage (c): Resend Pro required → platform £48.68, total £688.68; FX close wording; VAT note | Stackguide desk research |
| 2026-10-16 | Lovable Pro → £22/mo (annual £19/mo); +Lovable (b) £119.70, (c) £710.68; prefer pricing-page GBP | Stackguide desk research (Lovable pricing page re-check) |
| 2026-10-16 | Stage (a) + Lovable Pro corrected £0.00 → £22.00 | Stackguide desk research |
| 2026-10-23 | USD prices re-converted at the Bank of England reference rate, 1 USD = 0.7489 GBP (16 Oct 2026), the one rate used site-wide (was 0.7535, exchangerates.org.uk 15 Oct 2026 close); £ figures and totals re-derived | Bank of England series XUDLUSS, checked 2026-10-23 |