ERPFlow — Multi-Tenant SaaS ERP with Native AI Assistant and EU E-Invoicing

ERPFlow is a full business operations platform for freelancers, consultants and small-to-medium businesses — invoicing, CRM, inventory, finance, HR and reporting in one multi-tenant SaaS. We built it end-to-end with a native AI assistant that answers natural-language questions grounded in each tenant's actual data, all in two months on Next.js.

The ambition

Most small businesses juggle five tools to do what ERPFlow does in one. The brief was to build a product where a consultant could issue a compliant invoice, track the customer in CRM, log an expense, see the P&L impact, and ask an AI "what was my revenue from this client last quarter?" — without leaving the app. And it had to scale across organizations with strict tenant isolation and per-seat billing out of the box.

What we built

Multi-tenant architecture

Every query is tenant-scoped at the database layer, not in application code — the kind of isolation where a bug in a controller can't leak data across organizations. Role-based access (owner / admin / member) is enforced at the same layer. Invitations use a token flow with email verification.

Native AI business assistant

A chat interface built on AI Gateway lets users ask natural-language questions about their data — revenue trends, customer activity, team structure, expense history — and get answers grounded in their tenant's actual records rather than generic LLM knowledge. Provider choice is configurable per deployment.

EU-compliant e-invoicing

Every invoice exports to Peppol BIS Billing 3.0 (UBL 2.1 XML) natively — the EU standard for cross-border B2B invoicing. PDF generation for offline copies works alongside the XML export.

Per-seat Stripe billing

Subscriptions via Stripe Checkout, with seat enforcement on invite and a customer portal for self-service billing. Webhooks keep seat counts in sync.

Real-time collaboration

Shared records update live across users as soon as another teammate creates or edits them. Interactive org-chart visualization shows reporting hierarchies; an integrated map renders office and location records with geocoding.

Enterprise-grade audit trail

Every create / update / delete is captured in an activity log, searchable by user, entity and action — the kind of observability SMBs rarely get outside of enterprise tools.

Bulk operations and data mobility

Multi-select bulk operations (delete, activate, status change) across all major entity types, plus CSV import/export — so teams migrating from spreadsheets or other tools aren't starting from zero.

Trilingual out of the box

English, Estonian and Russian with locale-routed pages and a searchable locale switcher. The help center articles are fully localized.

Production hardening

Standards-grade security headers (CSP, HSTS, frame protection, permissions policy), bot protection on public forms, tiered cache lifetimes for hot and cold reads, and multi-region deployment for EU latency.

Tested

Unit tests and end-to-end tests with coverage tracking. Because an ERP that corrupts your financial data is worse than no ERP.

The result

A product SMBs can actually live in. Compliant where compliance is non-negotiable, opinionated where opinionation saves setup time, and extensible where teams need it to fit their workflow. Two months from kickoff to shipping, on a stack that costs pennies per tenant to run.