kelvinct
Kelvin Chang · builder

Build the change you want to see in the world.

I build the tools I use. Small browser tools for the gaps I kept seeing. One job each, no sign-ups, all in your browser and stored locally. Nothing's saved to the cloud. Try them out, then meet the person behind them.

The tools

15 live
001

Who doesn't follow you back?

Drop your Instagram export: see who doesn't follow you back, who unfollowed you since last time, who's ghosting your request. Then open profiles in batches.

InstagramRuns locallyZip upload
002

Which watershed are you in?

Type any U.S. address and see the watershed it sits in (the USGS Hydrologic Unit Code boundary), drawn on a live map, from sub-basin down to local subwatershed.

Live mapUSGS dataOpenStreetMap
003

What exactly is dougan?

豆乾 is an umbrella term, not one food. A field guide to 13 kinds of Taiwanese dried tofu, sorted by how each is pressed, braised, fried, or fermented. Photos and diagrams, runs in your browser.

Field guide13 varieties豆乾
004

How old is your cat in human years? (or dog or pet)

Enter your cat's age (or birthday) and see how old they'd be in human years, on the real vet curve (not the multiply-by-7 myth). Live graph you can scrub across, runs in your browser.

Cat mathRuns locallyLive graph
005

Is your wallpaper truly OLED black?

Drop a wallpaper and see what percent is true #000000, the black that switches AMOLED pixels off. Then snap the near-black pixels to pure black and download a PNG. Runs in your browser, nothing uploaded.

AMOLEDRuns locallyPNG export
006

Need a QR code for your WiFi?

Turn your WiFi network (or any link) into a QR code, add a caption printed above it, and download a PNG or SVG. Your network password never leaves your device.

WiFi & linksRuns locallyPNG + SVG
007

How many weeks do you have left?

Enter your birthday and see your whole life as a grid, one box per week: the lived ones filled in, the current one ticking live. Or map any span — in seconds, days, weeks, months or years.

Memento moriRuns locallyLive ticking
008

How much time do you have left with your parents?

Enter their birthdays (and anyone else you love) and see the time you statistically have left together, in years, months, days, or visits. Averages, not predictions, counted gently. Runs in your browser, nothing uploaded.

FamilyRuns locallySaved on-device
009

Who is actually winning at Nertz?

Add everyone playing and score every round. Enter a player's leftover Nertz pile plus either the cards they got to the middle or the cards still in front of them, and the other number fills itself in. Optional handicap tells each player how many cards to deal next.

Card gameRuns locallySaved on-device
010

How do you cook the perfect steak?

The easiest, tastiest steak you'll ever make. Salt a rib eye, roast it low to 250°F, then sear it screaming-hot in cast iron. Two numbers do the work. No basting, no resting, plus the videos if you want to nerd out.

Reverse searRib eyeCook's guide
011

Who is climbing to A at Tractor?

Track a game of Tractor (Sheng Ji). Every player gets a card with a − and a +, so you just tap whoever moved; the board keeps everyone climbing from 2 to A, with a chart and history. Turn on Advanced mode for hand-by-hand scoring from the points the opponents captured.

Card gameRuns locallySaved on-device
012

Want the stickers out of a LINE pack?

Paste a LINE Store link and get every sticker as a transparent PNG, at the largest size LINE serves, in one ZIP. Animated packs convert to GIF too. The images go straight from LINE to your device, nothing uploaded.

LINE stickersRuns locallyZIP of PNGs
013

Want your WHOOP and Oura on any screen?

Dash puts your health numbers on a page you can leave open on a spare monitor, a tablet, or the old Kindle in your drawer. Unlike everything else here, it connects to a server, and this page says exactly what that means before you sign up.

WHOOP + OuraConnected serviceReads on e-ink
014

Want your MacBook Pro brighter than macOS allows?

KelvinXDR takes the built-in XDR display up to 159%, and keeps working during protected video from Netflix and Apple TV+. It also controls external monitors and puts a brightness HUD under the notch. Free, open source, and this page explains the install.

Mac appOpen sourceUp to 159%
015

Where is my Amtrak train, and when does it actually get here?

Pick the station you are leaving from and the one you are going to. It finds the next train Amtrak is really tracking on that route, then tells you when it is expected at your station, how late it is, and where it is right now. It keeps rechecking on its own while anything is uncertain. Unofficial, not affiliated with Amtrak.

Live trackingAny Amtrak routeAuto-refresh
016

In the workshop

More tools land here as I build them.

Oh, and who I am

The human
Now building tinuai.com →
Tinu AI

It sits in your team's daily work, writes the summaries, captures the decisions, and remembers who did what.

Kelvin Chang

And the person behind the tools. I'm Kelvin, a builder and product manager. I spent ~3 years shipping crypto products at Coinbase, was employee #2 at a pre-seed startup, and studied at the University of Michigan School of Information. These days I'm building Tinu AI.

I build with Product management UX research 0→1 launches Next.js React TypeScript Python Prisma Data viz

Where I've built

Experience
2022–25

Coinbase · Product Manager

Owned USDC Rewards on Coinbase Prime, launched Wallet Explore 0→1, and shipped ML coin recs, cutting CB Pay's buy-funnel drop-off 60% and Prime reporting time 95%, then led the Prime Canada launch.

2023

Sustainable Bitcoin Protocol · Head of Product

Employee #2 at a pre-seed startup: led product, engineering and design for renewable-energy-certificate verification in Bitcoin mining.

2021–22

Microsoft · Capstone UX Designer

Redesigned accounts.microsoft.com: new navigation and activation surface, ~2× projected engagement.

2021

EY · Workforce Advisory (PAS)

Change-management personas and impact analysis for a Fortune 500 client.

Education

University of Michigan · M.S. Information

M.S. Information · B.B.A. (Ross, Magna Cum Laude) · B.S. Information (4.0). Taught SI 305: Python & Pandas.

Say hello

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