There is a difference between an agency that once built a SaaS for a client and one that operates SaaS products for its own revenue. AICLEX Technologies runs WhatsPilot (WhatsApp automation from ₹1,599 a month), Siteboard (real-estate plot management at ₹1,00,000 a year) and Zonvo (AI voice calling). We handle churn, failed payments, tenant isolation and support tickets every week, and bring that to founders building their own product.
This page explains how we architect multi-tenant SaaS, how subscriptions and GST billing work in India, what the build looks like in phases, and what founders typically get wrong. If you are a domain expert, a CA, a principal, a logistics operator, with an idea for software in your industry, this is written for you.
Multi-tenant architecture without the jargon
A SaaS serves many customers (tenants) from one codebase and usually one database. Tenant A must never see tenant B's data, yet you should not deploy a separate server per customer. We solve this with a tenant ID on every row, row-level security in PostgreSQL, tenant-scoped API tokens, and automated tests that attempt to cross tenant boundaries and must fail. Siteboard serves many developers from one deployment, each with their own projects, plots and brokers.
Our recommended stack is Next.js for the web app, Node.js APIs, PostgreSQL with a job queue for background work such as WhatsApp sends and reports, Redis for caching and rate limiting, and hosting on AWS or Vercel with the database in Mumbai. Plans and feature flags live per tenant, so upgrading a customer from Starter to Pro is a database change, not a deployment.
- One codebase, one deployment, strict per-tenant data isolation
- Roles inside each tenant with audit logs
- Plan limits enforced in the API, not just the UI
- Error tracking, uptime alerts and usage metrics from day one
Subscriptions, billing and GST for Indian SaaS
Recurring billing in India has quirks. UPI AutoPay and card mandates carry RBI limits and re-authentication rules, so the product must handle a failed renewal gracefully: a grace period, WhatsApp and email reminders, then a soft lock rather than data deletion. We integrate Razorpay Subscriptions or Cashfree, generate GST-compliant invoices with both GSTINs, and support annual plans paid by bank transfer against a proforma invoice for larger clients.
You also need trial logic, prorated upgrades and downgrades, launch coupons, and a billing page where tenants download invoices themselves. In WhatsPilot, self-service invoices alone removed a large share of support emails, so we build this into every client SaaS.
How we build a SaaS product in phases
Phase 1, product definition (2 to 3 weeks): ideal customer, the one workflow the product must nail, pricing tiers and success metrics, delivered as a written spec, data model and fixed-price proposal. Phase 2, design (3 weeks): Figma prototypes of onboarding, core workflow, settings and billing, tested with prospective customers. Phase 3, build (10 to 20 weeks): two-week sprints with staging releases, starting with authentication and tenant setup, then the core workflow, billing and integrations.
Phase 4, private beta (3 to 4 weeks): 5 to 15 real customers use the product while we fix what they trip over and you settle pricing. Phase 5, launch: hardening, documentation, a status page and handover of monitoring dashboards. A focused MVP reaches beta in 4 to 6 months; a broader product takes 8 to 12. Afterwards we continue as your product engineering team on retainer or hand over to your hires with documentation.
- Product definition and data model: 2 to 3 weeks
- Prototype and customer validation: 3 weeks
- Sprint-based build with staging releases: 10 to 20 weeks
- Private beta, then public launch: 5 to 6 weeks
Founder mistakes, ownership, security and scaling
Building for everyone produces a product useful to none; WhatsPilot works because it targets specific jobs such as coaching enquiries and order updates. Delaying billing until the end usually reveals a data model that cannot support plans, so we build billing early. Kubernetes and microservices on day one burn budget; a well-structured monolith on PostgreSQL serves thousands of tenants and can be split later.
You own the product outright: repository in your GitHub organisation, infrastructure in your AWS or Vercel account, domains and gateway in your company's name, with architecture docs, infrastructure as code and a runbook so a future in-house team can take over. Security includes tenant isolation tests in CI, encrypted secrets, backups with tested restores, audit logs, two-factor admin login, DPDP-aligned consent and deletion flows, and an incident process.
From you we need a committed product owner for weekly reviews, 5 to 10 prospective customers for validation and beta, clear pricing hypotheses, and company accounts for AWS, Razorpay and the domain.
Who this is for
- Domain experts (CAs, educators, doctors, logistics operators) who see a software gap in their industry
- Funded founders who need a technical partner rather than a first engineering hire
- Agencies and consultancies productising a service they currently deliver manually
- SMEs that built an internal tool and want to sell it to peers as a subscription
- Existing SaaS companies needing a rebuild, billing overhaul or move to multi-tenant architecture
Why choose AICLEX™
We operate three SaaS products
WhatsPilot, Siteboard and Zonvo give us daily experience with tenant isolation, failed renewals, support load and feature prioritisation.
Billing designed for India
Razorpay and Cashfree subscriptions, UPI AutoPay limits, GST invoicing, proforma flows for annual deals and graceful failed-payment handling are built in.
Scale without over-engineering
A well-structured monolith on Next.js, Node.js and PostgreSQL that serves thousands of tenants, split into services only when metrics require it.
Handover-ready engineering
Architecture docs, infrastructure as code, runbooks and CI pipelines mean your future team inherits a product, not a puzzle.
Pricing
A focused multi-tenant SaaS MVP with authentication, core workflow, admin console and subscription billing usually starts around ₹6 to ₹12 lakh. Broader products with mobile apps, multiple integrations and advanced reporting typically range from ₹12 to ₹30 lakh. A fixed-price written proposal follows the product definition phase, with milestone payments and GST invoices; ongoing engineering retainers are quoted monthly.
Frequently asked questions
How much does it cost to build a SaaS product in India?+
A lean multi-tenant MVP with billing generally starts around ₹6 to ₹12 lakh. Products with mobile apps, several integrations and complex reporting run ₹12 to ₹30 lakh. Cost is driven by workflows and integrations, not screens alone. We price fixed milestones after a short product-definition phase so the estimate rests on a real spec.
How long does it take to launch a SaaS?+
Expect 4 to 6 months from kickoff to private beta for a focused product and 8 to 12 months for a broader one. Building billing and tenant isolation early and validating with real customers during design prevents the rework that usually stretches timelines. Staging releases every two weeks keep progress visible.
Who owns the intellectual property and source code?+
You do, completely. The repository sits in your GitHub organisation from the first commit, infrastructure runs in your cloud accounts, and the agreement assigns all IP to your company. We do not reuse your product code elsewhere. Open-source libraries keep their own licences, which we list for you.
How do you keep each customer's data separate and secure?+
Every record carries a tenant ID, PostgreSQL row-level security enforces it, API tokens are tenant-scoped, and automated tests attempt cross-tenant access and must fail before release. Encrypted backups, audit logs, two-factor admin login and Mumbai-region hosting complete the baseline enterprise buyers ask about.
Can you handle subscriptions, GST invoices and failed payments?+
Yes. We integrate Razorpay Subscriptions or Cashfree for UPI AutoPay and card mandates, generate GST-compliant invoices automatically, support proforma and bank transfer for annual plans, and build grace periods with WhatsApp and email reminders for failed renewals. Customers download invoices from their own billing page.
Can we start small and scale the product later?+
Yes, and we recommend it. Launch with one core workflow, a simple plan structure and a solid data model. Because the architecture is multi-tenant from day one, plans, features, integrations and mobile apps added later build on the same foundation, which is how our own products grew.