Flask + Python · Worldwide
Most small businesses pay £100-300/month for SaaS tools they barely use. A focused custom Flask app usually replaces three of them, pays itself back in 4-6 months, and never raises its prices on you. Built by one developer, deployed to your infra, source code yours from day one.
Reference build: Cleaning Fairies invoicing app — Flask + SQLite + WeasyPrint, delivered in 24 hours.
Common project shapes
No two backoffice tools are the same — that's the point of building custom rather than renting SaaS. But most projects sit inside one of these four shapes. Each is doable solo in 1 day to 4 weeks depending on scope.
Client database + invoice generation + payment tracking + PDF export. Optional recurring schedules, late-payment reminders, partial payments, multi-currency. The Cleaning Fairies build replaced their previous QuickBooks subscription entirely. Typical scope: 1-3 days.
Calendar interface, customer self-service portal, staff schedules, capacity rules, email reminders. Integrates with Stripe for deposits, with Twilio/IONOS SMTP for notifications. Typical scope: 1-2 weeks.
Custom views of your own data: leads, jobs, inventory, KPIs. Replaces "shared Google Sheet" workflows that have grown beyond what a spreadsheet can handle. Role-based permissions, audit logs, exports. Typical scope: 1-3 weeks.
Connect the SaaS tools you already pay for: pull leads from your website into your CRM, sync invoices to Xero, export Stripe payments to your accounting, scrape competitor prices into a dashboard. Each integration: a few hours to a few days.
Stack
Python 3.12, Flask (or FastAPI for API-heavy projects), Peewee or SQLAlchemy ORM, SQLite for small apps, Postgres for anything that'll scale. WeasyPrint for PDF generation, ReportLab when WeasyPrint isn't enough, Pandas for reporting. Stripe/PayPal SDKs for payments. SMTP via IONOS or SendGrid for transactional email. Deployed to Hetzner, DigitalOcean or your own infra — your choice, source code yours from commit one. No vendor lock-in, no "agency hosting" markup, no opaque infrastructure.
Pricing
Hourly billing creates the wrong incentives — slow developers earn more. Every Flask project here is quoted fixed-price after a free 15-minute discovery call. You see the exact number before any code is written. Working in GBP, USD or EUR.
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