I Built a Multi-Tenant SaaS Platform Solo: Here’s the Architecture Behind SISWIT

119 database tables, 5 modules, one founder — lessons from building CRM, CPQ, and CLM into a single platform

Most growing businesses I talked to were stuck juggling three or four disconnected tools — a CRM for leads, a separate quoting tool, another app for contracts and e-signatures. None of them shared data. Every deal meant manual copy-pasting between systems.

So I built SISWIT — a unified cloud platform that combines CRM, CPQ (Configure-Price-Quote), and CLM (Contract Lifecycle Management) into a single multi-tenant SaaS product. This is the story of how it’s architected, the hard decisions I made, and what I learned building it mostly solo.

The Core Problem: Multi-Tenancy Done Right

• Every single query is scoped through a shared helper — no raw queries anywhere in the codebase
• Row Level Security (RLS) enforced at the database level, not just the application layer
• Soft deletes everywhere — nothing is ever physically deleted
• Every mutation writes to an audit log — who changed what, when

Why Supabase Over Firebase

I needed Postgres specifically — relational data with real foreign keys made sense for a system where a lead becomes an opportunity, which generates a quote, which becomes a contract. Supabase gave me Postgres + Auth + Edge Functions + Realtime in one platform, so I wasn’t stitching together five separate services just to get a working backend.

The Role Hierarchy

B2B SaaS needs real permission layers, not just “admin vs. user.” Here’s how SISWIT structures access:

What I’d Do Differently

Honestly — I’d invest in background job infrastructure earlier. Things like contract expiry alerts and async document generation started as “just call it synchronously” and later needed a proper job queue. Retrofitting that is more painful than designing for it from the start.

Closing Thoughts

Building a full multi-tenant SaaS platform alone teaches you fast that architecture decisions made in week one are still felt in month twelve. If you’re building something similar, happy to talk shop — and if you want to see what we built, SISWIT is live at siswit.com.

I’m Piyush Solanki— I designed and built SISWIT end-to-end. Connect with me on https://www.linkedin.com/in/piyush-solanki-326a1a205/ or check out more of my work on https://github.com/PiyushSolanki038.

[embed]SISWIT | Unified Cloud Platform for CPQ, CLM & CRM SISWIT empowers enterprises with a unified cloud platform for Configure-Price-Quote (CPQ), Contract Lifecycle…siswit.com

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Software Architecture, SaaS, React, Startup, Software Engineering

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