Why it took a long time to build that tiny link preview on Wikipedia

Yesterday, my team completed the launch ofpage previews” — a feature now deployed to hundreds of language editions of Wikipedia. We are seeing up to half a million hits every minute to our API to serve those cards that show when you hover over any link.

Preview cards now show when you hover over a link ohhh yeeehh (and yes, I use Wikipedia’s mobile skin for my desktop browsing). Text from the Wikipedia articles on icebergs and water, CC BY-SA 3.0. Images left to right, top to bottom: #1 by Kim Hansen, CC BY-SA 3.0; #2 by Andreas Weith, CC BY-SA 4.0; #3 via the National Library of New Zealand, CC0.

We had to choose a thumbnail

We had to generate a summary

Consider how HTML is needed to generate summaries for content where subscript is important such as the chemical formula of water, shown here. Text from the English Wikipedia article on water, CC BY-SA 3.0; image by Kim Hansen, CC BY-SA 3.0.
Location information features at the beginning of many articles proving problematic for summarising Wikipedia articles…
… as does pronunciation information. Text via the English Wikipedia’s article on Inle Lake, CC BY-SA 3.0.
Sometimes content inside parentheses is important, as this example suggests. Identifying when they are important is hard. Text from the English Wikipedia article on the periodic table, CC BY-SA 3.0; image by Offnfopt, public domain.

We work with our community

Design design design

We had to instrument it

We had to scale our API to support you

Thank you thank you thank you

--

--

Get the Medium app

A button that says 'Download on the App Store', and if clicked it will lead you to the iOS App store
A button that says 'Get it on, Google Play', and if clicked it will lead you to the Google Play store
Jon Robson (David Lyall)

Travel fanatic, writer, web dev british hippyster on a mission to make the web all happy with rainbows, unicorns etc