Is there a good alternative to Flickr/Smugmug and Instagram?

I would say Pixelfed. It is a federated image sharing platform. The code is libre (AGPL).

If the main federated alternative to Twitter is Mastodon, the main federated alternative to instagram/flickr is definitely Pixelfed.

https://pixelfed.org/

Also worth noting: it uses ActivityPub, and Mastodon users (and many other systems) can see and interact with Pixelfed users in most ways that matter.

In a lot of ways it's just a photo-optimized UI for ActivityPub. Which is generally a good thing.

I’d say it’s an alternative to Instagram, but not Flickr. A huge distinguishing feature of Flickr is that it keeps high-quality versions of uploaded photos. Instagram and Pixelfed compress to a low quality. Pixelfed’s UI also suggests that it’s more of an Instagram replacement, i.e. more about the social media aspect than about the photos. The photos are just an excuse to do social media.

> Yahoo was the one that started introducing limits

Yahoo. Yahoo! Yahoo broke Flickr almost overnight and then took several months to revert the damage. Infinite scrolling (no way to see someone's first uploads). Wannabe social-media guff. I gave up then and only keep my portfolio for historical reasons.

I liked the forums. It used to be like any other single-topic forum site.

Then Yahoo bought it tried to make it more like Instagram, and suddenly every forum was a porn spam forum.

Like Reddit, the old interface is still there, but it's not default.

Just add "?details=1" after the username/

They did the same to Tumblr.

I recall Flickr before was free up to a certain resolution, at the time it was something very low like 800 pixels or less than 2mb. During Marissa's CEO days, they pushed Flickr and introduced the unlimited storage for all users. I believe after it was sold to Smugmug, the storage was back down to being limited again.