AI Field-Service SaaS App
Leads, quotes, jobs, invoicing, payments, dispatch, and an AI Butler — one platform for trade businesses.
A full-stack AI-powered field-service SaaS built mobile-first for Swiss tradespeople — electricians, plumbers, HVAC specialists, carpenters, painters, and contractors. The platform replaces the patchwork of paper notebooks, spreadsheets, and WhatsApp threads small trade businesses run on today. Leads, quotes, jobs, invoices, payments, scheduling, and dispatch all live in one app — across a Flutter mobile app (iOS + Android, offline-first), a React admin panel for the office, and a built-in AI Butler that drafts quotes from voice or photo. Fully live in production with Swiss QR-Rechnung invoicing, Stripe Terminal Tap-to-Pay, TWINT, and English / Deutsch / Français / Italiano.
Project at a glance
A production-grade, AI-powered field-service SaaS for Swiss trade businesses. The platform unifies the full six-stage business workflow — Lead → Quote → Job → Invoice → Payment → Review — across three surfaces: a Flutter mobile app (iOS + Android, offline-first with SQLite), a React + Vite admin SPA for the office, and an OpenAI / Anthropic / Groq multi-model AI Butler that drafts quotes from voice or photo. Built for the Swiss market with QR-Rechnung invoicing, CHE-UID validation, Swiss VAT (8.1% / 2.6% / 0%), Stripe Terminal Tap-to-Pay, TWINT, and four-language UI (EN / DE / FR / IT).
Trade Businesses Are Still Running on WhatsApp, Spreadsheets, and Paper
- No single system for the full workflow — electricians, plumbers, and contractors juggled WhatsApp for contact, spreadsheets for quotes, paper for jobs, and separate accounting software for invoices, losing hours every day to admin.
- Quoting on-site was slow and error-prone — no way to generate a professional, accurate quote at the customer's kitchen table, so jobs were lost to faster competitors.
- No offline mobile solution — field workers in basements, rooftops, and rural areas had no reliable tool; apps that needed a live connection were useless on real job sites.
- Swiss compliance was a manual nightmare — QR-Rechnung invoices, correct VAT rates (8.1% / 2.6% / 0%), and CHE-UID validation were done by hand, slowly and with frequent errors that delayed payment.
- Getting paid on-site was impossible — businesses chased bank transfers for days or carried bulky card terminals; there was no lightweight phone-based payment option.
- Dispatch was a whiteboard problem — scheduling field workers used physical whiteboards or shared calendars with no live availability, causing double-bookings and missed appointments.
- Multi-language markets were underserved — Swiss tradespeople work across German, French, Italian, and English cantons, and no tool served all four languages from a single app.
How We Built One App to Replace the Entire Trade Business Stack
Metaviz AI built a tri-surface, AI-powered field-service platform — Flutter mobile app, React admin SPA, and AI Butler — all powered by a single FastAPI backend. Every pain point was directly addressed.
WhatsApp threads for customer contact; spreadsheet quotes emailed the next day; paper job sheets on clipboards; manual, error-prone QR-Bill creation; cash only or chasing bank transfers; a physical whiteboard for dispatch.
One app from lead capture to review; AI Butler drafts quotes in seconds on-site; digital jobs with photos and signatures; automatic Swiss QR-Rechnung generation; Stripe Tap-to-Pay + TWINT on the phone; a real-time drag-and-drop dispatch board.
The Platform Modules — Six Stages, Three Surfaces, One Backend
Butler AI
Multi-model AI (OpenAI GPT-4o, Anthropic Claude, Groq) that drafts quotes from voice, text, or photo. On-device speech via Sherpa-ONNX — no audio leaves the phone. pgvector semantic search over past quotes and jobs.
Leads & CRM
Full lead pipeline with source tracking, status management, and one-tap conversion to quote. Replaces the WhatsApp contact flow.
Quotes Module
On-site quote builder with Swiss VAT line items (8.1% / 2.6% / 0%), deposit %, validity period, branded PDF, and voice-to-quote via Butler AI.
Jobs & Field Work
End-to-end job management: before/during/after photos, on-device signatures, recurring jobs, templates — all working offline in SQLite.
Swiss QR-Rechnung
Automated compliant QR-Bill invoice PDF with per-line VAT, CHE-UID validation, cantonal address fields, and postal code validation.
Payments
Stripe Terminal Tap-to-Pay, TWINT, Stripe Checkout (subscriptions), manual bank transfer with auto-reconcile, Stripe Connect payouts.
Dispatch Board
Real-time drag-and-drop scheduling with live availability matrix (available / booked / unavailable / on leave). WebSocket fan-out.
Schedule & Maps
Day/week calendar with OpenStreetMap job pins, service-area radius, address autocomplete and reverse geocoding.
Auth & Security
Passkeys (FIDO2/WebAuthn), Face ID / Touch ID, magic link, Google/Apple sign-in, 2FA. GDPR export and full audit logging.
Multi-Tenant RBAC
Four roles: Field Worker / Dispatcher / Manager / Admin with calibrated access to quoting, billing, dispatch, and analytics.
Multi-Language
EN / DE / FR / IT with one-tap switch. Locale-aware formatting, per-region legal pages (Impressum, Datenschutz, AGB).
Subscription Billing
Pro / Business / Enterprise tiers via Stripe Subscriptions — trial-to-paid, seat pricing, Stripe Connect onboarding, usage metering.
Designed for every screen
Web
- Full leads, quotes, jobs, invoices, and orders management from a desktop browser
- Real-time drag-and-drop dispatch board with live team availability awareness
- Stripe Terminal Tap-to-Pay via @stripe/terminal-js for front-desk payments
- Leaflet + react-leaflet map with job pin clustering and service-area visualization
- Subscription and billing management dashboard
- Analytics and reporting with PDF / Excel export
- Role-based views — Admin / Manager / Dispatcher / Field Worker
- Full multilingual UI via i18next (EN / DE / FR / IT)
Mobile
Platforms: iOS & Android (Flutter), offline-first
- Offline-first dashboard — all data accessible with zero signal via SQLite local store
- Lead pipeline: capture, track, and convert leads to quotes from the field
- On-site quote builder with voice input (Sherpa-ONNX on-device), Swiss VAT line items, deposit %, and branded PDF
- Butler AI chat — describe a job by voice, text, or photo and receive a drafted quote instantly
- Job management: before/during/after photo capture, on-device signature, completion notes, recurring jobs
- Swiss QR-Rechnung invoice generation — one tap, compliant PDF ready to send
- Stripe Terminal Tap-to-Pay — on-site card payments from the phone, no hardware needed
- TWINT and manual bank transfer payment options
- Day/week schedule with OpenStreetMap job pins and service-area radius overlay
- Push notifications via Firebase Cloud Messaging — new jobs, quote accepted, payment received
- Passkeys, Face ID / Touch ID biometric login — one-handed in a van
- One-tap language switch: EN / DE / FR / IT — no app restart
- Cache-age indicators when offline (e.g. 'viewing cached data from 2h ago')
- Prioritised background sync on reconnect — status updates first, then signatures, invoices, photos
Full control, behind the scenes
- Real-time drag-and-drop dispatch board — drag job cards across team members; live availability matrix (available / fully booked / unavailable / on leave); WebSocket fan-out for instant updates
- Full CRUD on leads, quotes, jobs, invoices, customers, and products/services
- Swiss QR-Rechnung invoice management — generate, preview, send, and track payment status
- Revenue dashboard — Stripe subscriptions, Tap-to-Pay, TWINT, bank transfer — all reconciled
- Team management — invite members, assign roles, set working hours, service areas, exception dates
- Analytics — job completion rates, revenue per tradesperson, quote conversion rate, average job value
- Celery background job monitoring via Flower — AI embeddings, notification queues, CSV imports
- GDPR data export and full audit log on sensitive operations
- Customer CRM with booking history, communication log, and review management
Butler AI
An embedded in-app AI assistant (Flutter mobile + React admin SPA) that drafts quotes from voice, text, or photo. Model-routed via PydanticAI — OpenAI GPT-4o for vision, Anthropic Claude for reasoning, Groq for speed. On-device speech via Sherpa-ONNX (no audio leaves the phone) and pgvector RAG over past quotes and jobs so every draft gets smarter over time.
System design
The rules that run the product
- Every entity follows the six-stage lifecycle: Lead → Quote → Job → Invoice → Payment → Review. Stage transitions trigger automated status fan-out via WebSocket and push notification.
- Quotes carry per-line Swiss VAT rates (8.1% / 2.6% / 0%) and can include deposit percentage and validity period. Accepted quotes auto-convert to Jobs.
- Swiss QR-Rechnung invoices are generated only after a Job is marked complete and require a valid CHE-UID and IBAN. PDF is generated server-side via reportlab + qrcode.
- Butler AI is model-routed by task: Groq for low-latency drafts, GPT-4o for vision/photo analysis, Anthropic Claude for complex reasoning. PydanticAI validates all structured outputs.
- Offline sync follows a strict priority queue: job status updates → signatures → payment records → invoices → photos. Conflict resolution uses server-wins with a local audit trail.
- Dispatch board respects per-member working hours, service areas, and exception dates. Availability matrix broadcast in real time via FastAPI WebSocket.
- RBAC enforced at API middleware (FastAPI role-scoped JWT) and UI level. Field Workers can only access their own jobs and schedule.
- Stripe subscriptions determine feature access tiers. Stripe Connect requires vendor onboarding before Tap-to-Pay or payouts are enabled.
- Voice-to-Quote: Field worker opens Butler → speaks job description → Sherpa-ONNX transcribes on-device → PydanticAI routes to Groq or GPT-4o → structured quote draft returned → worker reviews and sends PDF
- Job Completion: Job opened → before photos (offline) → work completed → after photos + signature (offline) → sync on reconnect → QR-Rechnung invoice auto-generated → Tap-to-Pay or TWINT → review request sent
- Dispatch Flow: Manager opens dispatch board → new job card appears → drag to available team member → WebSocket fans out → field worker receives push notification
- Celery Beat sends quote follow-up reminders at configurable intervals after sending
- Firebase Cloud Messaging push sent on quote accepted, job assigned, payment received, and review submitted
- pgvector embeddings computed asynchronously via Celery whenever a new quote or job is saved
- Alembic migrations run automatically on deployment via Coolify container startup hooks
- Stripe webhook handler auto-reconciles payments and updates invoice status within seconds
Everything inside
Butler AI (Voice, Text & Photo)
- Voice-to-quote: describe a job out loud, receive a fully drafted, VAT-accurate quote
- Photo analysis: photograph a fault — Butler identifies and drafts the job
- Multi-turn conversation with full message history across sessions
- Semantic search across past quotes and jobs via pgvector RAG
- Fully on-device speech (Sherpa-ONNX) — no audio sent externally
- Multi-model routing: Groq for speed, GPT-4o for vision, Claude for reasoning
Leads & CRM
- Lead capture with source tracking (web form, phone, referral, walk-in)
- Lead status pipeline with one-tap conversion to quote
- Customer profile with full job and communication history
- Direct contact shortcuts: phone, WhatsApp, email
Quotes
- On-site quote builder with Swiss VAT line items (8.1% / 2.6% / 0%)
- Deposit percentage, payment terms, and validity period
- Automated follow-up reminders after sending
- Branded PDF sent via email in one tap
- One-tap accept — automatic job creation
Jobs & Field Work
- Full job detail: customer, address, photos, notes, assigned team member
- Before / during / after photo capture — works offline
- On-device customer signature — works offline
- Recurring job scheduling and job templates
- Real-time job status push to office
Swiss QR-Rechnung Invoicing
- Compliant QR-Bill PDF generation — one tap after job completion
- Per-line VAT rates (8.1% / 2.6% / 0%) with CHE-UID validation
- Cantonal address fields and Swiss postal code validation
- Compatible with PostFinance, UBS, Raiffeisen, ZKB, and all Swiss banking apps
Payments
- Stripe Terminal Tap-to-Pay — on-site card, contactless, Apple/Google Pay — phone only
- TWINT Swiss instant payment
- Manual bank transfer with automatic reconciliation
- Stripe Connect onboarding for contractor payouts
- Pro / Business / Enterprise subscription billing via Stripe Subscriptions
Dispatch Board
- Real-time drag-and-drop job scheduling (dnd-kit + WebSocket)
- Live availability matrix per team member
- Per-member working hours, service areas, exception dates
- Instant fan-out to office devices and field worker push notifications
Offline-First Mobile
- Full app functionality with zero signal via SQLite local store
- Cache-age indicators showing data freshness
- Prioritised background sync queue on reconnect
- Works in basements, rooftops, rural areas — wherever the job takes you
Auth & Security
- Passkeys (FIDO2/WebAuthn) — phishing-resistant, device-native
- Face ID / Touch ID / fingerprint biometric login
- Magic link and Google / Apple sign-in
- 2FA via Twilio Verify (SMS OTP)
- Argon2 password hashing, iOS Keychain / Android Keystore token storage
- GDPR data export and full audit logging on sensitive operations
Multi-Language (EN / DE / FR / IT)
- One-tap language switch — no restart required
- Compile-time-safe Flutter ARB files for mobile
- i18next with browser language detection for web admin
- Locale-aware number, date, and currency formatting
- Per-region legal pages: Impressum, Datenschutz, AGB Handwerker
Built on a modern stack
Outcomes that move the business
- Shipped a tri-surface SaaS (Flutter mobile + React admin + AI Butler) from a single FastAPI backend — cutting feature-development time by ~40% with zero API drift across clients
- Integrated three AI model providers (OpenAI, Anthropic, Groq) through a single PydanticAI routing layer — giving Butler the right model for every task
- Built fully on-device speech recognition via Sherpa-ONNX — voice input works offline, no audio ever leaves the phone, solving both privacy and connectivity
- Generated compliant Swiss QR-Rechnung invoices automatically via reportlab + qrcode — eliminated manual QR-Bill creation
- Implemented passkey (FIDO2/WebAuthn) authentication on Flutter and web — phishing-resistant, biometric-first login for field workers
- Delivered four-language support (EN / DE / FR / IT) with one-tap switching, locale-aware formatting, and per-region legal pages
Customer-day compression: capture a lead in the morning, send a quote from the customer's kitchen, complete the job in the afternoon, and collect payment before leaving the driveway — all from one app. Eliminated the WhatsApp + spreadsheet + paper + separate-accounting stack. Offline-first SQLite keeps field workers productive in basements, rooftops, and rural job sites with automatic prioritised sync on reconnect. Stripe Terminal Tap-to-Pay turns every phone into a card reader — no terminal, no invoice chasing.
