Also their use of AJAX and inline editing was revolutionary - probably created the whole industry around first Bootstrap, then jQuery. Man - spent so much time to emulate that light pastel yellow fade when you edited a title and saved it (later provided by jQuery).

On the backend side, Cal Henderson published the details of Flickr's architecture in "Building Scalable Web Sites". It was a reference at the time, the "Designing Data-Intensive Applications" of another generation.

I remember using machine tags Last.fm back, back in the day (late 00s, maybe even 2010). That was still the time of the mashup/remixed web pages, and APIs were more open and you could do very fun stuff crossing Google Maps, Facebook, Craigslist and whatever.

Then, Last.fm was a good site to keep track of the events (concerts/festivals) you were planning to go or you had visited.

Every event had an ID (let's say, 3792998), and you could add photos to Flickr with a machine tag with certain prefix (in this case, the tag would be lastfm:event=3792998). So, when you visited an event on Last.fm, it'd query the Flickr API for photos tagged with that machine tag, and show photos from that concert.

It was cool, but I think Last.fm removed that feature at least 10 years ago...

Here you can still list Flickr photos tagged like that:

https://flickr.com/photos/tags/lastfm:event=*

Edit: Oh, I didn't remember that Flickr would also link back to the Last.fm event. The Internet was quite a different thing back then. Flickr blog post about the feature: https://code.flickr.net/2008/08/28/machine-tags-lastfm-and-r...

When I saw the headline I immediately thought of the API, this does a great job explaining its relevance in its time! It’s interesting how even programmers then were trying to learn the concept, but now “API” is common language even nontechnical people generally understand and use in conversation

In a recent thread talking about Flickr URLs I mentioned a couple of interesting technical features that Flickr had also done that I thought were worth celebrating. When gwern mentions that you should write in more detail about those things I feel you have to take that seriously. This is that attempt.

Is it just "machine tags" or was it also tags on the web in general?

I feel Flickr and del.icio.us were the first mass adopters of tags, and everyone else followed, but I'm not sure.

then we have companies that went the opposite way with the abomination called graphql

They didn’t mention feature flags! Their blog post on feature flags was seminal.

Flickr was the first site I saw where you could edit some text on the screen inline, without a complete page reload to get an “edit” form.

Today this is utterly ordinary. At the time, it was remarkable.

Excellent post. Very nostalgic. Interoperability as advantage was a thing people loved back then. But the advent of aggregators showed that you’d rapidly just become a commodity. The community that was Facebook would instead be FriendFeed because that aggregated Facebook and others. And then you had to lock it down or die. Interesting times.