Solopreneur case studies — 3/9
Solopreneur and side-business cases
49–72 of 201
A solo operator earning 102 million yen a year. How an affiliate marketer who fell from 75 million to 50 million broke his own record
Kuroneko-ya reported annual income of 75 million yen in 2016, 69 million in 2017, and 50 million in 2018 — three straight years of decline — before recovering to 102 million yen in 2021. With zero employees and almost no outsourcing, he has published, year by year, the story of shifting his main revenue from SEO affiliate marketing to selling his own courses.
The Half Marathon Guide: “Just Half Marathon Race Info” Adds Up to $1.2M — Sold to an Individual Buyer
The Half Marathon Guide, a site cataloging half marathons across the U.S., earned founder Terrell Johnson roughly $1.2M (about ¥180M) cumulatively before being sold to individual buyer Michael Mazzara. A case study in the compounding power of unglamorous information curation: "the race calendar."
¥2.5 Million a Month From a Chat-Analysis App: 85% of Traffic From TikTok, 37.5% CVR — an Indie Design "Reverse-Engineered From the Distribution Channel"
IsTalk, a chat-analysis app by Kei, an engineer with 15 years of experience, reached 600K cumulative downloads and over 4,600 subscriptions for roughly ¥2.5 million/month, hitting #1 in the App Store Utilities category. 85% of traffic comes from TikTok or friend referrals, and CVR improved from 24.2% to 37.5%. First-class real data on an indie app, published with screenshots.
Ammesso.it: 70,000 Users on a Med School Exam App, Sold as a Side Project for Mid Six Figures
Ammesso.it, an Italian medical school entrance exam prep app, sold to fellow exam-prep company Testbusters in June 2021 with about 70,000 users, for a mid-six-figure dollar amount. It was essentially a two-person side project.
Wellness Blog Root + Revel Passes from One Individual to Another: An Everyday Scene from the "Used-Blog Market"
Root + Revel, a holistic wellness blog, was transferred from founder Kate Kordsmeier to an individual buyer, Sarah Ware. A record of "person-to-person blog sales" — not a headline deal — functioning as an ordinary, everyday transaction.
With 86 Twitter followers, Kindle royalties reach ¥75,000 a month. Ten books, two years, and what an all-in bet on SEO looked like
With just 86 Twitter followers, an author built Kindle royalties to ¥75,000/month across 10 books over two years, after pivoting hard to Amazon-internal SEO.
Potion, the Notion-to-Website Builder, Sells for $300K — From Solo Developer to Individual Buyer
Potion, which turns Notion pages into fast websites, was grown by solo developer Noah Bragg in build-in-public style and sold for $300K (approx. ¥45M) to individual buyer Bruno Morency. A defining example of individual-to-individual micro-SaaS deals.
Elementary Librarian: a $1M+ Exit on Hyper-Niche Lesson Plans for School Librarians
Elementary Librarian, which sells lesson plans to elementary school librarians, was sold to SureSwift Capital for $1M+ (over ¥150M). A case of triple-layered niching — teachers, within that librarians, within that elementary school — creating a monopoly.
Postcode Shipping: A Shipping-Rate Shopify App Sells to Solo Investor Fund MicroAngel — “Micro PE” as a New Kind of Buyer
Postcode Shipping, a Shopify app that calculates shipping rates by postal code, was sold to MicroAngel Fund, run by individual investor Eyal Toledano. A real-world example of "micro PE" — an individual buying small SaaS businesses and earning operating returns.
Freelance Writers Den, a Paid Community for Writers, Sells for Six Figures: Engineering the Teacher's Retirement
Freelance Writers Den, the paid community for writers run by Carol Tice — whose blog reaches a million readers a year — was sold to Jara Publishing for six figures (USD). A case of an educational community sustained for over a decade being handed over as its founder retired, complete with a price cut and a resale.
SEO Content SaaS Contentpace Sells to an AI Content Company at 2.5x Revenue
Contentpace, a SaaS for building and optimizing SEO article outlines, was sold to AI content generator Content at Scale for 2.5x revenue. Rather than fighting the generative AI flood as a standalone tool, the founder chose to become a feature inside an AI company.
36,500 subscribers, but two years of total revenue in the high hundreds-of-thousands of yen. An AI-explainer YouTube channel's hourly wage: ¥416
An AI-tool explainer channel grew to 36,500 subscribers two years after launching in April 2024. But two-year total revenue was only in the high hundreds of thousands of yen, recently a few tens of thousands of yen per month. Across 112 videos at an estimated 30 hours each, that works out to an hourly wage of ¥416. The turning point wasn't stagnation — it was the year-two conclusion that ad revenue had plateaued, reached after every stated goal had been met.
"Budgets Are Sexy": 13 Years of Anonymous Personal Finance Blogging, Sold to a Motley Fool-Affiliated Network
Budgets Are Sexy, the personal finance blog masked blogger J. Money wrote for 13 years, was sold to the Motley Fool-affiliated Soapbox Financial Network. Proof that a long-term brand — and an exit — can be built on a "character" without ever revealing your real name.
Arvid Kahl: From 23 Subscribers to 7,600 — a $3,000/Month Newsletter Built Across 183 Issues After Selling His SaaS
Arvid Kahl sold a SaaS with $55,000 MRR in 2019, then started a newsletter from 23 subscribers. By issue 183 it reached 7,600 subscribers and $3,000/month, sold through 6 sponsor slots per issue.
With a $70 ad budget he got 130 installs and 2 paying users. Then he left Android for a Chrome extension and sold 7 copies in a week
The developer spent about 10,000 yen on Play Store ads for an Android app and got over 130 installs but only 2 subscribers. The same developer then launched two Chrome extensions with a combined 41 installs, and 7 of those users bought the Pro version — revenue overtook the app within a week. Conversion rose from roughly 1.5% to roughly 17%.
After quitting four side hustles, a company employee topped ¥400,000/month selling articles on note within five months
After medical leave for depression, a company employee dropped four side businesses — resale, blogging, YouTube, and crowdsourcing — before moving to selling articles on note. He self-disclosed a first sale of ¥500 on day three, growing to over ¥400,000/month five months later.
Dan Koe: From $10K to $2.5M in Annual Revenue in 4 Years — the “Zero Sponsors, Own Products Only” One-Person Business
Dan Koe's annual revenue: $10K in 2019, $100K in 2020, $150K in 2021, $800K in 2022, a projected $2.5M for 2023. We break down the structure of a one-person business built entirely on $150-$8,000 own-brand courses with zero sponsorship income.
90 quiz apps, 8.2 million downloads, ¥20 million+ in revenue — the real picture of mass production, where only 2 in 10 hit
A solo developer who specializes in quiz/personality apps released 90+ titles over four years, reaching 8.2M downloads and over ¥20M in revenue, while admitting flops like a 5,000-download "romantic type" quiz.
Website Investing: Paid Subscriptions Stalled at 70 — a Free Tier in Front Led to $7,500/Month and a Six-Figure Sale in Seven Months
Richard Patey's paid newsletter, charging $49/month, plateaued at 70 paying subscribers. After moving to Substack in May 2020 and putting a free tier in front, it reached 100 paying subscribers, 2,700 free subscribers, and $7,500 in monthly revenue seven months later — and sold for six figures.
A tech-book ranking site built from 300,000 Qiita articles hit 100,000 yen in revenue three weeks after launch
A solo developer aggregated roughly 300,000 Qiita articles via API to build a ranking of 4,000 technical books, and the site earned 100,000 yen within three weeks of launch. The turning point was setting aside his own passion project after a prior failure and rebuilding the concept from scratch by studying and copying successful examples.
A stay-at-home mom's blog, year two: 203,000 yen annual revenue. PV grew 19x, revenue grew only 5.8x
The blog "Delako Blog" launched in March 2021. Year one: 26 posts, 4,050 PV, 34,700 yen revenue. Year two: 53 posts, 76,658 PV, 203,000 yen. This article examines from the numbers why revenue grew only about 5.8x even though PV grew about 19x.
A crypto side-hustle app went from ¥300,000/month to a few thousand yen. 20,000 installs, ¥18,000-per-referral, and how it vanished
A manufacturing employee's hobby crypto demo-trading app "BitVirtual" hit 20,000 installs and ¥300,000/month during the 2017 boom, with exchange affiliate payouts up to ¥18,000/referral — then collapsed to a few thousand yen a month a year later.
A trivia TikTok channel earned about ¥9 million over two years — average monthly income of ¥400,000, and RPM collapsing into the ¥20s
A trivia-focused TikToker disclosed 24 months of earnings: about ¥9 million total, ¥400,000 average monthly, but RPM has fallen to around ¥20 since April 2025.
She put all ¥50,000 of her sales balance into ads. How a handmade artist's monthly sales went ¥70K → ¥590K → a ¥2M peak
Surume, a jewelry artist on Creema, put her entire ¥50,000 balance into promotional ads and watched monthly sales climb ¥70K → ¥140K → ¥290K → ¥590K. Peak monthly sales hit ¥2M, with 3 straight months over ¥1M recently.