The £100/month constraint isn't about being cheap. It's about being intentional. Engineer from the budget down, and you end up with a stack that's leaner, clearer, and shipped faster than a "whatever you need" stack ever is.

This post is a concrete build. Exact tools, 2026 prices in GBP, and the trade-offs behind each choice. The total comes in comfortably under £100/month and covers the full founder workflow: build, host, sell, communicate, analyze, automate.

The constraint

£100/month = £1,200/year. That's your budget for subscriptions. Out of scope: transaction fees (Stripe), domains (~£10/year), AI API credits if you build with them, and hardware. In scope: every SaaS that renews monthly.

The budget does two things. First, it caps waste - you can't accumulate 30 tools. Second, it forces the question "what's earning its place?" on every line. Most founders spending £500/month have exactly the same capabilities as founders spending £100 - plus five tools they haven't opened this quarter.

The stack

CategoryToolWhyMonthly
Editor / codingCursor ProAI-native editor, best-in-class£16
FrameworkNext.jsFree, open sourceFree
HostingVercel Free100GB bandwidth, plenty for launchFree
Database + authSupabase Free500MB Postgres, 50k MAU authFree
PaymentsStripeTransaction fees only, no subscriptionFree*
Transactional emailResend Free3k emails/mo on freeFree
NewsletterBeehiiv FreeUp to 2,500 subs freeFree
Docs + planningNotion FreeUnlimited pages for soloFree
Issue trackingLinear FreeUnlimited members, 250 issuesFree
DesignFigma Free3 files, unlimited personal draftsFree
AnalyticsPlausible BasicPrivacy-first, 10k page views£7
Product analyticsPostHog Free1M events/mo, session recordingsFree
Customer supportCrisp FreeChat widget, shared inboxFree
SchedulingCal.com FreeUnlimited personal bookingsFree
AI assistantClaude ProScripting, coding, research£16
Domain + DNSCloudflare FreeDNS, CDN, basic securityFree
File storageGoogle Drive (via Workspace)If needed - bundled with email£5
Total£44/month

*Stripe takes 2.9% + 30p per transaction. No subscription fee.

£44/month for a complete, production-grade stack. That's well under budget - which leaves room for 1-2 specialist additions as they earn their place.

What the budget allows you to add

Under £100/mo, you have around £55/month of flex. Use it where it pays back fastest:

  • Cursor Max (£16 → £80) if you're coding heavily - unlimited AI calls.
  • Beehiiv Scale (£80/mo) if you're past 2,500 subs and want the referral program.
  • Notion Plus (£8-10/mo per user) when you start collaborating.
  • Figma Pro (£14/mo) when you outgrow 3 files.
  • Plausible Growth (£15/mo) once you pass 10k monthly page views.
  • Cal.com Team (£9/mo) if you add a co-founder and want round-robin.

Pick one or two based on the constraint that hurts most. Don't add all five.

What you're deliberately not paying for

Under £100/mo, you're explicitly saying no to:

  • HubSpot, Salesforce, any enterprise CRM. Use Notion databases or a Google Sheet until you have 50+ leads. Then Attio at £27/mo.
  • Mailchimp. Beehiiv and Resend both have better free tiers and better UX.
  • Jira. Linear Free is strictly better for small teams.
  • Zapier Pro. Make's 1,000 free ops/mo covers most early-stage automation. Upgrade at £10/mo when it doesn't.
  • Dedicated design tools beyond Figma - Canva, Adobe, etc. Figma handles 95% of founder design work.
  • Calendly. Cal.com is free and better for individuals.
The real skill isn't finding cheap tools. It's recognizing which capabilities don't earn a line item yet.

When to break the £100 cap

The budget is a heuristic, not a law. Break it deliberately when:

  • A paid tool would replace your time at a clear exchange (e.g. a £200/month accountant saves you 10 hours of bookkeeping).
  • A revenue-producing tool pays for itself (e.g. Cal.com Team saving partner scheduling for a deal-focused business).
  • Free-tier limits actively block growth (Vercel bandwidth, Supabase storage) - upgrade the specific line, not the whole stack.

Don't break the cap because you "feel like" you should have more. The feeling usually fades in 48 hours; the subscription renews monthly.

How to stay under £100

  1. Quarterly audit. 90 minutes, every 90 days. Count every subscription. Kill anything unused. See the audit framework.
  2. One-in, one-out rule. Adding a new paid tool? Something else comes off. Forces the question of what you're actually replacing.
  3. Annual plans only for load-bearing tools. Monthly billing makes cancellation painless. Annual is fine once a tool is unambiguously working.
  4. Trial-date calendar block. Every trial you start goes on the calendar with a "cancel or upgrade?" reminder one day before renewal.

Build this stack in 30 minutes

The Stack Builder sets up each of these tools with sensible defaults, connects them, and gives you a checklist to launch. Under £100/mo, from zero.

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Further reading