wnumbr is back
I built wnumbr back in 2017 as a simple idea: point it at any web page, tell it which number to watch, and it tracks changes over time. Prices, stats, population counters - anything with a number on a page. (web archive)
It ran for four years on .NET before I shut it down in 2021. The original version served its purpose with my obsession of watching so many numbers (most of them were private), but maintaining it became impossible with increasingly busy life..
Fast forward to 2026: while between jobs, taking time off before starting the next role, I rewrote the entire system from scratch using Rust and React, with significant help from Claude. The rewrite took a fraction of the time of the original. I focused on decisions; it handled the boilerplate.
How it works
Create a monitor, give it a URL, and pick how to extract the number:
- CSS selector - grab text from any HTML element
- XPath - for more precise targeting in complex pages
- Regex - match a pattern anywhere in the page source
- JSON path - extract from API responses directly
There's a visual element picker that lets you click on the number you want - no need to write selectors by hand. Set a frequency (hourly, daily, whatever), and wnumbr crawls the page and records the value automatically.
If you have your own data source, you can skip the scraping and push values directly via API. Every monitor gets a chart showing the value over time, with deltas between data points.
A chart for every number
The web is full of interesting numbers that only exist as a single value on a page - no history, no chart, no way to see how they've changed. A country's population on Wikipedia. The price of something on a random store. A GitHub repo's star count. River water levels. Air quality indexes. Exchange rates from some government site.
These numbers change, sometimes in interesting ways, but unless someone is specifically publishing a time series, that history is lost. wnumbr gives you the chart that doesn't exist yet. Point it at any number, let it collect data, and over days and weeks you get a picture that wasn't available before.
You can try it at wnumbr.mustakim.dev.