I've decided to write this post after wasting a lot of time while trying to submit my first post.

Outdated blog posts

If you do a quick search about this topic you might find these articles:

Although they were not wrong and they have served their purpose, they are all OUTDATED.

Solution

The trick explained in these other posts is still valid, however the old domain (namely https://img1.steemit.com) is no longer valid.

The new valid prefix URL you should use is: https://steemitimages.com/50x50/ where the first 50x50 represents width X height.

So for instance if you have an image:

https://steemitimages.com/DQmcKYjeDDCXMiUhvV2prUbrZx2HG2A8rpevTUNQMTkqNpx/rick.jpg

You can resize it by prefixing the URL https://steemitimages.com/WxH/ with the desired size:

https://steemitimages.com/50x50/https://steemitimages.com/DQmcKYjeDDCXMiUhvV2prUbrZx2HG2A8rpevTUNQMTkqNpx/rick.jpg

Examples

Resized 50 x 50

Resized 100 x 100

Resized 200 x 200

Original 749 x 749

Caveats

At the moment it's only possible to resize an image while keeping the Aspect Ratio. This means that even if you specify a size of 100X400 on the image above (which is squared) the resulting size will be 100X100 regardless.

Enjoy!

Resize images on Steemit editor [Updated 2018]