4 Personal Apps I Built in My Own Product This Week. None of Them Could Ever Be a Startup

This week I built four little apps inside Shelf — the AI desktop-app generator I'm shipping — for problems I wasn't planning to solve. None of them could be a SaaS. Each took 20–40 seconds to generate. Combined, they save me roughly 40 minutes a week.

Posting them here partly because IH readers will recognise themselves in one or two, partly because "I dogfood my own product" is easy to claim and harder to show. Here's the showing.
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## 1. Standup-to-Self

Prompt:

> "End-of-day check-in. One textarea for 'what I worked on today' and one for 'where I'm picking up tomorrow'. Save with date. On open, show yesterday's 'tomorrow' note at the top in big text."

Why I needed it. I was losing about 10 minutes every morning re-orienting on what I'd been doing the day before. A Notes app didn't solve it because I had to remember to open Notes. With Shelf already in my dock, the note is the first thing I see.

Why no SaaS builds this. A SaaS that solves this has to also be a journal, a planner, a habit tracker, a "system." Mine is one textarea and a date column. It will never be a startup. It's been perfect since I built it.

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## 2. Tweet Draft Queue

Prompt:

> "Tweet ideas list. Add text, optional tag (ship / thinking / snark / data). Mark as posted with link. Show only unposted by default, sorted oldest first."

Why I needed it. I have tweet ideas all day and lose 90% of them by evening when I'd actually post. Notion would technically work; opening Notion takes me four seconds and a context-switch. Shelf is already open. That friction delta is the difference between actually posting and not.

Why no SaaS builds this. Hypefury, Typefully, Tweet Hunter — they all do this. Each costs $20–$50/month and includes 40 features I don't use. The tax for needing one feature is the other 39.

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## 3. MRR What-If Calculator

Prompt:

> "Pricing calculator. Sliders for visitors per day, free-to-paid conversion %, monthly churn %, average revenue per user. Live MRR projection for month 3, month 12, and steady-state. Toggle: 'what if I doubled visitors'."

Why I needed it. I keep rebuilding the same spreadsheet to sanity-check pricing decisions. The spreadsheet keeps adding parameters and getting harder to compare to last week's version. This is the spreadsheet, except it's an app, it's persistent, and the sliders feel right.

Why no SaaS builds this. ProfitWell-class tools exist, attached to actual revenue data. Mine is for hypothetical scenarios — playing with numbers before committing to anything. Different job, no market, perfect Shelf use case.

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## 4. Founder Mood Check

Prompt:

> "Once-a-day check-in. Question: 'how's it going?' (1–10 slider) + one-line text 'why'. Save with date. Show the last 30 days as a sparkline."

Why I needed it. Building solo for a year does interesting things to your sense of how the project is going. I wanted a sparkline of me, not the metrics. Every week I look at it I can tell whether last Tuesday's 3-out-of-10 was the start of a real dip or just a bad Tuesday.

Why no SaaS builds this. There are 4,000 mood-tracker apps in the App Store. None are built for a founder context, and all of them want my phone notifications and a freemium upgrade flow. Mine asks one question and draws the line.

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## What this actually tells you about Shelf — and about your own product

A SaaS founder usually has to choose between the thing you're building for customers and the thing you'd build for yourself if you had infinite time. Shelf collapses that choice for me. The customer-facing product and my own quality-of-life tools come out of the same prompt box.

There's a wider read for IH readers thinking about their own products: when your product is cheap enough for users to deploy on themselves, the "do they actually love this?" question gets a brutally honest answer. They start using it for things you never built it for. You feel it the day they do.

Which is, increasingly, the only version of dogfooding I trust.

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## Try one

- Download Shelf: [getmyshelf.app](https://getmyshelf.app) — free, desktop, BYOK or use the hosted free tier.

- Pick the prompt above that looks most like a problem you'd actually use this week. Paste it in. The point isn't to use my four apps. The point is to feel how short the loop is between "I wish I had X" and "oh, I have X."

- Post yours back here. I'd genuinely like to see what other IH builders make when they don't have to justify it to a roadmap.

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Shelf is a free desktop app. Data stays on your machine. The point isn't to replace big software — it's to fill the gap big software was never going to fill.