If you're a consumer, Google Photos offers unlimited (optimized) photo storage and delivery for free.
If you're a Developer, the number one service for uploading and delivering images (and most types of files) is Filestack. They offer a free plan, and scale all the way up to Enterprise plans that handle some of the top brands worldwide.
Yea, you can get a VPS for less than $5 a month, if you shop around. I was just pulling a number out of my hat; I don't have a price list immediately to hand. My point is only that it's cheap.
I don't know anything about DigitalOcean Spaces, but if you need more space apparently it's the way to go. 25 GB is room for a lot of images though.
Wasabi is even cheaper ATM, the main drawback for DO and Wasabi being the minimum $5/month, otherwise they charge per use like AWS S3 and have some API compatibility.
I don't allow sign ups. It's for me and a few friends only. I pay $5/mo and host my own images - after I grew sick of moving from pomf.se clone to pomf.se clone as they'd all eventually shut down.
Image/File hosting isn't profitable, Sir_Cmpwn [1] has a good write up on why it simply isn't a profitable/good business to get into. In fact, if you read the replies to Sir_Cmpwn's post you'll see I replied... and was using mixtape.moe at the time. And guess what? safe.moe, my other listed option, has shut down too. So it has been 2~ years before both of the image hosts I was using have shut down. safe.moe shutting down is actually why I began hosting my own images with my own domain.
The problem is they don't scale. Once you stop being niche and become popular - the cost to host everything starts growing exponentially while the people willing to donate does not. You'll eventually be spending more on the server(s) than you earn from it. You tank. You shut down. Then someone else thinks they can do better and the cycle continues. This is why there are very few free [0] file hosts that are capable of surviving for long periods of time. I've ran the math once and assuming I grew to 1,000~ regular users a month, I'd have about a years' runway before I'd have to begin charging users or shut down; assuming no donations and none of the 1,000 users are particularly abusive of the service. With donations it might last two or even three years, but it would be an inevitable shutdown as I wouldn't be willing to pay to provide the service past that point. 2-4 years is how long I could use a given host before it went to shit (suffered from the "poison" of needing to monetize to survive) or shut down (couldn't monetize well enough), so it seems like my math isn't too unique to myself either. And this is just the financial side of things - there's the whole administration side of banning abusive users, dealing with DMCA's, dealing with child pornography, and the tech side of scaling, upgrading servers when needed, etc. It's a whole lot to take on.
Sir_Cmpwn, if you happen to read this, I suppose you can add mixtape.moe to your list in a 2019 update. :)
[0] Typically ads somewhere, but many are donation driven by supporters willing to pitch in.
It may shock you that scandalous names such as "Microsoft Azure", "Imgur", "Photobucket", "Imageshack" also have to deal with large amounts of child pornography and that the name of the file host has little to do with it, the mere existence of a file host is all it takes.
I also incur zero administrative costs from dealing with anything because I don't allow anyone to upload to my website (and never have). If you have a free file host, you will be dealing with child pornography within a few weeks, almost guaranteed. There are systems made to automatically deal with known/"common" images [0] [1]. Also to clear up a few things regarding the name, the domain of my site is "kimiwo.aishitei.ru". The name of my host is "Lovehost". The domain is Japanese and translates to "I love you". The software it runs is what is called "lolisafe".
I hope you can pay/donate to some decent file hosts, I really salute people who voluntarily host a free hosting service online and often donate to them if I have used their service.
Getting DMCA complaints or god forbid, child porn complaint can ruin their career or even life.
I use my own S3 bucket for long term images and https://catbox.moe for short term / sharing for friend/
While it lacks some image-hosting specific features (like gallery or tagging, etc) I use Triton for Object Storage[1] (formerly Manta) for hosting a good number of images and some videos. It works great, it's really cheap[2] and the CLI tools are very easy to use `mput ~~/stor/public/img/ -f somepic.jpg`
I just use a tiny PHP script [1] I made to upload and host my own files on a shared hosting server. It's not, perfect, and I need to update it a bit, but it works well enough.
If you're a Developer, the number one service for uploading and delivering images (and most types of files) is Filestack. They offer a free plan, and scale all the way up to Enterprise plans that handle some of the top brands worldwide.