In short6 min read
- OpenWhen grew from $17 in February to $436 in October with a free core and $3.99 upgrade.
- Answering people in existing conversations about missing someone drove growth more than paid ads.
- ChatGPT now sends a real share of visitors directly to the letter page, per the founder.
- Etsy printables and a month of ads produced zero orders, according to the founder.
Most side project stories you read online either start at $10k a month or skip the boring middle. This one is the boring middle, and that is exactly why it is useful. A solo founder built a simple web app with AI coding agents and grew it from $17 to $436 in monthly revenue over eight months, with no subscription and a single $3.99 upgrade.
By the end of this article you will know the exact pricing model, the two channels that worked, the two that failed, and a step-by-step checklist for building your own small “strangers pay for it” product. It will not make you rich overnight, and the founder is clear about that too. But it shows a repeatable path that a solo builder can follow today.
In this article
What OpenWhen Is
OpenWhen is a site for “open when” letters. You write a letter, seal it, and the recipient opens it when the moment arrives: open when you miss me, open when you can’t sleep, and so on.
The business model is deliberately simple:
- Writing a letter is free.
- A one-time $3.99 upgrade adds photos, voice notes, and nicer envelopes.
- No subscription.
The founder built it solo on Next.js, Supabase, Stripe, and Vercel, using AI coding agents to do much of the building. In their words, it is still small, but it is “the first thing I’ve built that strangers pay for.”
The Revenue Curve, Month by Month
Here are the monthly revenue figures the founder shared:
| Month | Revenue |
|---|---|
| February | $17 |
| April | $29 |
| May | $48 |
| June | $70 |
| July | $111 |
| August | $280 |
| September | $355 |
| October | $436 |
Two things stand out. First, the early months were tiny, under $50 for the first few months listed. Most people quit in that zone. Second, there is a noticeable jump between July and August. The founder did not break down exactly what caused that step change, so treat it as a reminder that compounding channels often look flat before they look steep.
Where the Money Actually Comes From
Every dollar here comes from one source: the $3.99 one-time upgrade. That means revenue depends on two things: how many people write letters, and what share of them decide the extras are worth paying for.
What moved the needle
The founder credits three things:
- Showing up where people already talk about missing someone, and answering them. Instead of pushing the product cold, the founder went into existing conversations about long-distance relationships, missing loved ones, and similar emotional moments, then actually helped. The product fit naturally into those threads.
- Free to write, one payment for extras. Removing friction from the core action meant more letters got written. The paywall only sits on the emotional “make it special” layer: photos, voice notes, envelopes.
- ChatGPT as a traffic source. According to the founder, ChatGPT now sends “a real share of visitors” straight to the letter page. They did not share an exact percentage.
That third point deserves attention. One commenter on the thread said they see 10-25 visitors a day from ChatGPT on their own small site without doing anything special beyond normal SEO. Another asked whether ChatGPT visitors convert better than social visitors, which is a question worth tracking on any product you build.
What didn’t work
The founder was equally open about the misses:
- Printables on Etsy: a month of ads and zero orders.
- Facebook and Instagram: lots of visits, but nearly all of them were recipients opening a letter someone sent them, not new customers.
That second point is a classic trap. A traffic chart can look great while the business stands still, because the visitors are not the buyers.
The Hidden Metrics That Decide If This Scales
The sharpest feedback in the community thread came from a commenter who argued that two numbers decide whether this compounds or stays a one-off:
- Payers per hundred letters written. While writing is free, this is the only honest conversion rate.
- Repeat writers within 60 days. With a single $3.99 purchase and no subscription, revenue only grows if the same person comes back for another occasion. Otherwise you refill the top of the funnel every month.
One reader also asked whether the $3.99 covers just one letter or all future letters. The founder’s answer was not shared, but it is a critical pricing decision if you copy this model. Per-letter pricing creates repeat revenue; a lifetime unlock maximizes conversion but caps lifetime value.
Turning recipients into writers
Two commenters made the same point from different angles: the Facebook and Instagram visitors are not wasted. Someone who has just opened a heartfelt letter is in the perfect mood to write one back. A gentle “write one back” button right after the letter opens could turn recipients into new writers, creating a loop where the product spreads on its own.
This is the most actionable growth idea in the whole case. If you build anything that gets shared one-to-one, your recipients are your cheapest acquisition channel.
Realistic Adjustments If You Copy This Today
You probably should not build another “open when” letter site. But the underlying pattern transfers well to many small consumer products:
- Pick an emotional, recurring moment. Birthdays, anniversaries, long-distance relationships, graduations, grief. People pay small amounts for things that feel personal.
- Keep the core free and charge for the “special” layer. Low-ticket, one-time payments remove subscription fatigue, but plan for repeat purchases from day one.
- Use AI coding agents to ship fast. The founder built this solo with a common modern stack. That lowers the cost of testing an idea, though you still need to handle payments, data, and reliability properly.
- Expect a slow start. The first several months here were under $50. Results depend heavily on how consistently you show up in conversations and how fast you iterate.
- Track source by buyer, not by visitor. Social traffic here was mostly recipients. Your analytics should tag where paying users come from, not just sessions.
- Write pages that answer specific questions clearly. If AI assistants like ChatGPT are going to recommend you, they need a clear, useful page to point to. The founder says ChatGPT sends people straight to the letter page.
How to Do It: Your Step-by-Step Checklist
Use this checklist to build and launch a small, OpenWhen-style product:
- Choose one emotional use case. Write down a single moment people already talk about online, such as missing someone or celebrating a milestone.
- Find where those conversations happen. List 5-10 forums, subreddits, or communities where people discuss that moment. Read for a week before posting.
- Define your free core action. Decide the one thing users can do for free that delivers real value on its own.
- Design a one-time upgrade. Pick 2-3 “make it special” extras, like media attachments or premium design. Decide upfront whether payment covers one item or all future items.
- Build a minimal version with AI coding agents. A stack like Next.js, Supabase, Stripe, and Vercel works for a solo builder, per the founder’s setup. Ship the smallest version that works end to end.
- Add a recipient-to-creator loop. After someone receives or views a shared item, show a soft prompt to create their own.
- Create clear, answer-style pages. Make a dedicated page that explains what your product does and who it is for, so search engines and AI assistants can understand and surface it.
- Show up and help, every week. Answer questions in your chosen communities genuinely. Mention your product only when it fits the conversation.
- Skip paid ads until you have proof. The founder’s month of Etsy ads produced zero orders. Validate organic demand first.
- Track three numbers monthly. Payers per 100 free users, repeat buyers within 60 days, and revenue by acquisition source. Adjust based on what they tell you.
Want to copy this playbook for your own side project?
Today, pick one emotional moment people already talk about online and list five communities where those conversations happen. Spend 20 minutes reading and answering one question genuinely before you write a single line of code.
Source: 8 months in, my side project went from $17 to $436 a month
Leave a Reply