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I Built a Family Planner We Actually Use (and It Costs £0/month)

A short, non-technical story about building a weekly family planner over Christmas: what it does, how my family shaped it, and how I used LLM agents without letting them run wild.

Disclaimer: LLM Agents wrote the code and the bugs. The ideas and most of the wording in this blog series are mine, but edited by LLMs because I am an engineer, not a copywriter. I’ve reviewed it to ensure it sounds like me, but if you spot weird phrasing, blame the robot.

Over the Christmas break I built a simple weekly family planner for my partner, my son, and me.

Not because I wanted “an app”, but because the basics kept slipping: PE kit, clubs, bin day changes, “what are we doing next Saturday?”, and the eternal scavenger hunt through calendars, WhatsApp threads, and school emails.

Family life is a messy distributed system that doesn’t accept incident tickets.

What it does

It’s a mobile-first weekly view you can scan quickly:

  • what’s on this week
  • what’s coming up soon
  • quick ways to add things without filling in a form

The goal isn’t “perfect scheduling”. It’s reducing the mental load: if someone asks “what’s on this week?”, the answer becomes “check the planner”.

Family Planner - This Week screen
The whole point: a week you can understand in ten seconds.

The real secret: iterate with the actual users

I built the first version for me. It worked. Then I handed it to my family and watched them use it.

They didn’t care about my neat architecture. They cared about whether it felt safe, fast, and obvious:

  • if adding something takes more than a few seconds, it won’t happen
  • if it feels like you can “break it”, people won’t explore
  • the best features are usually the ones that remove friction, not the ones that add power

That feedback loop shaped the app far more than any “feature roadmap” I could have invented on my own.

How I used LLM agents (without making a mess)

I did use LLM agents heavily, but not as “magic autopilot”.

My workflow was more like:

  1. write the rules first (data shape, safety constraints, “what we will not do”)
  2. treat the agent like a very fast junior developer (literal, eager, needs guardrails)
  3. ship small changes and actually review them
  4. test with real people, then iterate

The “rules first” piece matters. It’s the difference between “fast” and “fast, but you still own it afterwards”.

If you’re curious about this approach, AGENTS.md is the general idea: https://agents.md/

£0/month (on purpose)

I wanted something we owned, without a subscription, and without handing our family schedule to a random SaaS vendor.

This runs on Cloudflare’s free tier (for a small household, the numbers are tiny):

Want the technical version?

I wrote the full technical series separately so this post could stay readable. If you do want the deeper dive:

References

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