One person, 19 apps, 43 books

Apps, books, and tools that respect your attention.

JC Mobile App Studio is an independent studio run by one developer. The apps run on-device and never track you, the picture books explain how things work, and the journal says what I actually think about tech, money, and privacy.

Browse the apps See the books

15 apps on the App Store
3 in review
43 books on Amazon
330 articles
45 free tools

Start here

ChoreSight

ChoreSight is a household chore tracker built around accountability. A chore isn't done until someone submits a live photo of the finished work, skipped chores turn red and lock to the top of the screen, and any family member can take over an overdue task. Parents review and approve every submission from one dashboard.

See ChoreSight

ChoreSight on iPhone, iPhone Duo and iPad

The lineup

Every app, with its screen

15 apps, all on-device, none of them tracking you. Tap one for the full brief and the download link.

See the full lineup, with every screen

How it's built

No tracking. Ever.

The same three rules in every app, every book, and every tool.

On-device by default

Apple's Foundation Models do the work locally, so your notes, receipts, and health data are understood on your iPhone, not on a server. Where an app syncs or uses a cloud fallback, its own privacy page says so in plain words.

No tracking, ever

No analytics SDKs, no data sold. One app, WavCast, runs ads in its free tier and says so upfront, with a one-time purchase to remove them. That is the whole list of exceptions.

English and Español, day one

Bilingual is a feature here, not a translation bolted on later. Plantilla goes further and speaks ten languages, because the people who need it do too.

The books

Same studio, different medium.

I write picture books for the same reason I write apps: most things are explained badly. A storm is water and air doing loud work. Sleep is a whole crew on the night shift. 43 titles on Amazon in print and Kindle, most of them in four-book series.

All 43 books

The Wobbles Series · 4 books · Ages 3-7

Wobbles are wiggly little worry-creatures only Mara can see, and they grow bigger every time she keeps them secret. Each book puts her in one specific nervous moment, a new school, a sleepover, a checkup, a stage, and finds the same fix: say it out loud.

Three Dogs, One Park Series · 4 books · Ages 3-7

Luna, Sophie, and Joy are real dogs who share a real backyard with Joe. Each book pairs one park-dog moment, a storm, a vet visit, a new puppy, with a friendship or big-feelings lesson for kids who love animals.

The Goodbye Button Series · 4 books · Ages 3-7

It started as one small ritual: Mom draws a purple sun on Josie's palm and on her own, press yours and mine buzzes. Then it turns out the same trick, a tiny hand-drawn button and a grown-up's steady explanation, can be redrawn for whatever a kid is actually facing, a first sleepover, a scary new skill, a mistake that feels too big to fix.

Book and app pairings

Three Dogs, One Vet Day

VitalLedger, the vet visit in the book is the record you keep in the app

The Night Shift

Steady, a bedtime story about sleep crews, and a sleep planner for people who work nights

Where Did My Dollar Go?

DayCast, money explained for kids, and a spending tracker for the grown-up reading it

All 43 books

The journal

Tech, money, and privacy, explained plainly.

Honest reviews and plain-language explainers from the same desk that builds the apps. New pieces most days.

All articles

A living room at night lit only by a large Samsung TV showing the Netflix home screen, a London skyline at dusk visible through rain-streaked windows behind the couch, a remote and two mugs on the coffee table, photorealistic

Movies

What to watch this week: Black Doves season 2 lands overnight, Prime Video's Muhammad Ali series is out, and Bass X Machina is on Netflix

Black Doves season 2 drops all six episodes on Netflix at 3 a.m. Eastern Thursday, with Keira Knightley and Ben Whishaw back and Wallace preparing to become Prime Minister. The Greatest, Prime Video's authorized Muhammad Ali series with Jaalen Best, is out now, all eight episodes. Bass X Machina, LeSean Thomas's steampunk Western with Brian Tyree Henry, landed on Netflix Tuesday. Plus Stick and All's Fair season 2, and Friday's movies, led by The Cat in the Hat and Godzilla Minus Zero. Verified November 4, 2026.

Josuam Collazo · 4 min read

Six Android phones of different sizes laid out on a wooden table, each showing a software update progress screen at a different percentage, one tablet at the end of the row, soft window light

TechAndroid

Samsung's big update week, sorted: what actually shipped, which Galaxy has One UI 9 and which is still waiting, the S26 Ultra setup bug, and the first Pixel month without the Pixel 6

Samsung pushed dozens of updates last week and most of what was written about them was wrong, starting with the claim that the Galaxy S26 was only now getting One UI 9 in Europe. It has had it since September; what rolled out was a second October maintenance build. The real news was One UI 9 reaching the first tablets, the A55 and A35, and India's mid-range, while the S23 FE waits until January. Plus the S26 Ultra setup freeze Samsung has acknowledged, the S24 battery reports, where every model stands, and November for a Pixel now that the 6 and 6 Pro are done. Verified November 1, 2026.

Josuam Collazo · 7 min read

A big-box electronics store aisle, a PS5, an Xbox Series X and a Nintendo Switch 2 on display shelves side by side with large price tags, a shopper in the foreground reading one of the tags

TechGaming

The console race, by the numbers: PS5 up 22 percent, Xbox at a record low, Switch 2 cooling, and every box now costs more than it did in spring

Circana's September report is the clearest picture of the US console market in a year: PS5 units up 22 percent on Wolverine, Xbox Series units down 27 percent to the lowest September ever, Switch 2 down 14 percent and now second-fastest-selling in US history rather than first. Hardware dollars rose anyway, because the Series X is $799, the PS5 $649 and the Switch 2 $499. What the numbers say, what the briefing got wrong about prices, Microsoft's own Xbox results, and what I'd buy for the holidays. Verified October 31, 2026.

Josuam Collazo · 7 min read

All articles

Free to use

Small tools, no signup.

The same thinking as the apps, in 45 calculators that run entirely in your browser. Nothing is saved, nothing is sent.

All tools

Pet Kit 5 tools in one app

Pay Kit 8 tools in one app

Money Kit 8 tools in one app

Body Kit 7 tools in one app

Phone Kit 12 tools in one app

Install any of them to your home screen. They share what you enter and work offline.

/tools/final-paycheck Final Paycheck Calculator Last hours, overtime, unused PTO, and when your state says it is due. Open → /tools/free-trial-deadline Free Trial Deadline The exact cancel-by date, a reminder, and a calendar file. Open → /tools/ios-beta-calendar iOS Beta Calendar Latest betas, expected RC and release dates, and what your next update is. Open → /tools/pay-stub-decoder Pay Stub Decoder, EN + ES Every line on a US pay stub explained in plain English and plain Spanish. Open → /tools/bedtime-by-age Bedtime by Age A bedtime window from wake-up time and pediatric sleep guidelines, naps included. Open → /tools/vaccine-schedule Puppy and Kitten Vaccine Schedule A dated core vaccine timeline from the birth date, with a calendar export. Open →

All tools

Who builds this

One person, nights and weekends

I've been hooked on tech since my first Compaq and AOL dial-up, and I was the one family and friends called to fix their computers. By day I work in HR. Nights and weekends I build the apps, write the books, and publish the journal, all drawn from problems I actually had. No hype, no affiliate bait, just the stuff I would want a friend to tell me.

Josuam Collazo Designer & Developer, JC Mobile App Studio Learn more about Josuam

Apps, books, and tools that respect your attention.

ChoreSight

Every app, with its screen

No tracking. Ever.

On-device by default

No tracking, ever

English and Español, day one

What to watch this week: Black Doves season 2 lands overnight, Prime Video's Muhammad Ali series is out, and Bass X Machina is on Netflix

Samsung's big update week, sorted: what actually shipped, which Galaxy has One UI 9 and which is still waiting, the S26 Ultra setup bug, and the first Pixel month without the Pixel 6

The console race, by the numbers: PS5 up 22 percent, Xbox at a record low, Switch 2 cooling, and every box now costs more than it did in spring

One person, nights and weekends

Get in touch.