The $5 Fax: How a Weekend Project Became a Micro-SaaS

After 20+ years of running Monocube, my dev agency, I thought I’d seen every client request imaginable. Then I noticed a pattern: half our clients needed to fax documents. IRS forms, legal filings, signed contracts. They all complained about the same thing. Every fax service wanted them to create an account, pick a monthly plan, and commit to a subscription they’d use twice a year.

The problem nobody wanted to solve

Faxing is not exciting. Nobody is building a fax startup to pitch at YC Demo Day. But millions of people still need to fax the IRS, send signed documents to their lawyers, or file paperwork with government agencies that refuse to join the 21st century.

The existing solutions all assumed you were a power user: sign up, pick a plan, enter your credit card for a recurring subscription. For someone who needs to send one fax to the IRS, that’s absurd.

The weekend MVP

I already had our agency’s SaaS template (Nuxt 4, TypeScript, PostgreSQL, Stripe) ready to go. On a Friday evening, I stripped it down to the absolute minimum: upload a file, enter a fax number, pay $5, send. No signup. No account creation. No subscription.

By Sunday night, it worked. singlefax.com was live.

No signup, no subscription, no friction

This was the key decision that made everything else work. I’d watched agency clients abandon fax services at the signup wall. They didn’t want another account, another password, another monthly charge showing up on their credit card statement.

Guest send still asks for almost nothing: an email for the receipt, a file, and a fax number. No account. The price dropped from that first $5 to $0.99 for up to 10 billable pages (about +$0.08 after that, cap 50). Want to receive faxes? $4.99 for a 30-day number (first inbound included, extras $4.99), or a lifetime number at $97 Basic / $147 Pro. Incoming faxes after starter credit are $4.99 each. If the wallet is empty, the fax is held until you top up.

Letting SEO do the selling

I had zero marketing budget and zero audience. But I knew something useful: people don’t search for “online fax service.” They search for “how to fax documents to the IRS” and “send fax online without subscription.” These are purchase-intent queries. The person searching already has a document in hand and a deadline.

I wrote 9 blog posts targeting exactly these searches. How to fax IRS Form 2848. How to send a fax without a fax machine. Small business fax solutions. Each post ended with a simple call to action: send your fax now.

The posts took a few months to rank, but when they did, the traffic was incredibly high-quality. These weren’t tire-kickers. They were people holding a document, looking for the fastest way to fax it.

The lifetime number that customers asked for

I didn’t plan the lifetime fax number. Customers emailed asking for it. Small businesses and solo practitioners who received faxes regularly didn’t want to pay per incoming fax, but they also didn’t want a subscription. “Can I just buy a number and keep it forever?”

So I added it. It started at $99. It is $97 Basic or $147 Pro now: one-time payment, starter inbound credit, no yearly keep-alive. Incoming faxes after credit are still $4.99. It took an afternoon to implement. Now it accounts for a meaningful chunk of revenue, and those customers require essentially zero support.

Agency experience is the real unfair advantage

I see indie hackers spend months learning to deploy, struggling with Stripe integration, figuring out database schemas. After 20 years at the agency, all of that is muscle memory for me. I had a SaaS template, a deployment pipeline, and a Stripe integration I’d built dozens of times.

The weekend MVP wasn’t a heroic coding sprint. It was just applying skills I’d been honing for two decades on someone else’s dime. Every agency project, every client deadline, every production outage at 2 AM: it all compounds into the ability to ship fast and ship reliably.

The boring micro-SaaS that runs itself

SingleFax is not going to be a unicorn. It will never be on the front page of Hacker News. It solves one problem (sending and receiving faxes) for people who need it occasionally, and it charges a fair price with zero friction.

It runs itself. There’s no customer success team, no onboarding flow, no feature roadmap meetings. Just a simple service that works, a handful of SEO posts that bring in steady traffic, and a payment system that deposits money into my account.

After 20 years of building complex systems for clients, the simplest product I’ve ever made is the one that actually works for me.

Then the channels arrived

That was true in February. By Indie TM #16 the guest send was still the product (now $0.99, not $5), and the rest of the surface had grown.

HIPAA Secure is a paid extra on the website, with an electronic BAA. Pay-as-you-go is $6.50 for 1 to 10 pages or $10 for 11 to 50. Clinics that want a dedicated number add it to a subscription for +$20/mo. Medical faxes cannot ride in email, and they cannot go through MCP, WhatsApp, or email-to-fax. The customer opens them in the account. That is the point of the fee: the procedure, not a badge on the homepage.

People also wanted to send a fax from the tools they already live in. Email-to-fax (PDF to send@fax.delivery, number in the subject) and WhatsApp-to-fax are those pipes. EIN by fax is $9.99, the same idea pointed at Form SS-4. ChatGPT, Cursor, and Claude talk to SingleFax MCP. Autonomous agents can pay through Stripe’s Machine Payments Protocol. Credits sit next to the lifetime number: you keep the number, and an inbound fax stays locked until you top up. There is no inactivity fee. You do not lose the number if you go dark.

Companies can buy a monthly number if they want a page pool: $9.99 Standard or $29.99 Business. The stranger who needs one IRS form never has to open that door.

The inbound hold is live. Send is $0.99. A received fax with no credit sits locked until the owner pays $4.99 (or spends credit) to open it.

The room had a view on all of this. The #16 recap is what they said when the simple product started looking like a suite.