I built a SaaS for freelancers in my spare time — here's what I learned

#showdev #webdev #startup #javascript

The Problem I Was Trying to Solve

I'm a freelancer. And like most freelancers, I was using:

WhatsApp to send files to clients
PayPal to collect payments (and lose 3-5% in fees)
Gmail for invoices (copy-pasting from a Word doc)
DocuSign for contracts ($25/month just for e-signatures)
Random Google Drive folders for file sharing

It looked unprofessional. Clients lost things. I chased
payments for weeks.

I couldn't find one tool that did everything at a price
that made sense for a solo freelancer.

So I built it.

What I Built

PortalFlow — a client portal for freelancers.

Each client gets a unique portal link. Inside that link they can:

✅ View and pay invoices online (Stripe payments)
✅ Download shared files
✅ View and sign contracts
✅ See everything in one professional page

You (the freelancer) get a dashboard to:

Create and send invoices
Upload and share files
Write contracts and send for signature
Get paid directly to your Stripe account
Send automatic payment reminders

All for $7/month. Less than one DocuSign subscription.

The Tech Stack

Here's everything I used to build it:

Frontend

React 19 (Create React App)
TailwindCSS for styling
React Router for navigation
Deployed on Vercel

Backend / Database

Supabase (PostgreSQL + Auth + File Storage)
Row Level Security for data isolation
Supabase Auth for user management

Payments

Stripe Checkout for invoice payments
Each freelancer connects their own Stripe account
Payments go directly to the freelancer — no platform cut

Emails

Resend for transactional emails
Each freelancer uses their own Resend API key
Emails sent from their own domain

Hosting

Vercel (serverless functions for API routes)
Zero server management

The Hardest Parts

1. Per-user API keys

The trickiest architecture decision was payments. I wanted
payments to go directly to the freelancer — not to me first.

Solution: each user stores their own Stripe secret key in
Supabase user_metadata. When a client pays, the API looks up
that freelancer's key and creates the Stripe session with it.

No platform cut. No escrow. Money goes straight to the freelancer.

2. Serverless functions on Vercel

Moving from Express to Vercel serverless functions was a
learning curve. Each file in the api/ folder becomes an
endpoint. No shared state between requests.

3. Row Level Security in Supabase

Every query in the database is automatically filtered by
the logged-in user. No freelancer can see another
freelancer's clients or invoices — enforced at the
database level, not the application level.

What I Would Do Differently

Start with Stripe Connect instead of per-user keys (more complex but more scalable)
Use Next.js instead of Create React App (better for SEO and serverless)
Build the email system last — it caused the most bugs