CA's & Tax Web App Development

Web App for CAs/Tax Professionals & Their Clients — Secure Chat + Auto Document Vault (MVP)

Important: This must be a real, production-ready application — not a demo, prototype, or throwaway build. "MVP" here refers to feature scope (a focused first version), not build quality. It needs to run reliably for real users from day one and comfortably support around 10,000 people using it daily.

Project Overview

I'm looking for a developer to build the MVP of a web platform designed for Chartered Accountants (CAs), Tax Professionals, and Advocates to communicate and exchange documents with their clients.

The platform consists of three separate web apps:


CA App — used by the accountant/professional to manage clients, chat, documents, and fees
Client App — used by individual/business clients to chat and manage their documents
Admin App — a lightweight internal app for approving manual payments


Core Feature: Chat + Auto-Vault

The centerpiece of the app is a real-time 1-on-1 chat between a CA and their client. Any file sent in the chat (PDFs, images, Excel, etc.) is automatically saved into a document vault — no manual re-upload needed. Users tag each file with a category (e.g. ITR, GST, Bank Statement) and financial year, so documents can be searched and filtered later instead of getting lost across WhatsApp/email threads.

What Needs to Be Built

Authentication
Real phone number + OTP login via an actual SMS provider (e.g. Twilio, MSG91, or similar) — no hardcoded/demo OTP in the final build
Shared login flow across CA, Client, and Admin apps

Onboarding
CA: role selection, firm profile setup (logo, name, brand color), dashboard
Client: standalone signup, or join via CA invite link/bulk upload, or link to a CA later using a shared code + phone number
Many-to-many client–CA linking (a client can be linked to multiple CAs, and each CA only sees their own slice of the relationship)


Chat + Vault
Real-time 1-on-1 chat with file sharing
Automatic saving of shared files to a personal vault
Manual tagging popup (category + financial year) on upload
CA-side Global Vault (search/filter by client, category, year; multi-select + download)
Client-side Personal Vault with independent self-upload


Family Groups
Clients or CAs can create family groups with a "Head" member
Members can be added by phone number or by name only
Documents can be marked private (CA + uploader only) or visible to the whole group

Fee Tracking
Simple internal ledger for CAs (client, year, service, amount, paid/unpaid status)
Hidden from the client

Storage & Manual Payments
Flat free storage tier per CA account
Upgrade flow: CA submits a payment screenshot → goes into admin's approval queue → storage unlocks on submission and is revoked if rejected
No payment gateway integration — everything is manual/screenshot-based


Admin App
Queue for reviewing storage upgrade payment requests (approve/reject)
Queue for reviewing outsourced order payments
Combined feed of all pending approvals
(Optional) list of all registered CA firms and their storage usage


Recommended Tech Stack
Framework: Next.js (React, App Router) — single codebase, separate route groups for each app
Styling: Tailwind CSS
Backend: Supabase (Postgres + Storage + Phone OTP Auth)
Real-time: Supabase Realtime for chat
Hosting: Vercel


Open to a different stack if you have a faster/cheaper path to the same result, as long as it's easy to extend later.
Non-Functional Requirements (Must-Haves)


Production-grade, not a prototype. Proper error handling, input validation, and loading/empty states throughout — not just the "happy path."
Real-time chat and file uploads must be stable and fast under concurrent use, not just working for a single test user.
Scalable data model and queries — the app should be built so it can handle roughly 10,000 daily active users without major rework (proper indexing, pagination, no N+1 queries, sensible use of Supabase's connection limits, etc.).
Secure by default — signed URLs for file access, proper auth checks on every API route/data query (a client should never be able to see another CA's data), and no secrets exposed client-side.
Deployed to a real, stable environment (not just running on localhost), with basic monitoring/error logging in place.
Clean, documented, maintainable code — this codebase will be extended by a team later, so no shortcuts that would need a rewrite.


Deliverables
Fully functional MVP across all three web apps, deployed and accessible via URL
Source code handed over in a private repo
Brief documentation on setup/deployment


Success Criteria
A CA can sign up, set up their firm profile, and invite clients
A client can join and chat with the CA
Files sent in chat are automatically saved and show up correctly in both the CA's and client's vaults
A CA can search/filter the vault and find a document quickly
The storage upgrade → admin approval → storage update flow works end-to-end

Who I'm Looking For
A freelancer or small team comfortable working from a detailed written spec, experienced with Next.js + Supabase (or an equivalent modern web stack), who has shipped real applications to production before (not just personal projects or demos). You should be comfortable making sensible calls about scaling, security, and performance without needing everything spelled out. Ability to move fast on a tight budget while still delivering something solid, plus proactive communication on progress and blockers, is a must. I have a full detailed requirements document ready to share with the selected freelancer.