iOS 9 brought the ability to use "Content Blockers" with Safari. What exactly is a "content blocker"?

From Apple:

"Content blockers affect what content is loaded while using Safari."

In short, they can be used to block ads.

Not all content blockers are created the same.

I started testing content blockers around October of 2015. I looked for a few things with each blocker:

Removed ads should have their CSS collapsed to hide where they were. You don't want a bunch of big, empty boxes all over a web page, do you?

The ability to whitelist sites. I don't want to apply blanket rules to ever site, and having to tap "Reload Without Content Blockers" over and over is not ideal.

Being able to refresh the block list can be important. How old are the rules? How can you tell that the content blocker is actually up to date?

Not required, but the ability for the content blocker to hide the fact that it is blocking ads can be important.

There are two simple sites I test these on. Mac Rumors and Forbes. Why those sites? Mac Rumors has a lot of "ads in the middle of content" that looks horrible if you just hide the ads. You end up with white boxes all over the page. I test with Forbes because not only does it have nasty ads all over, it also tries to block you from viewing their site if they detect that you're trying to block ads!

These 19 content blockers were all available to download as of February 1st, 2016.

1Blocker

Ad Block Multi

Ad Control

Ad-Blocker

Adamant

AdBlockX

BlockBear

Blockr

Clearly

Crystal

Freedom

Lionz

NeverAds

Privacy

Purify

Rocket

Silentium

Vivio

Wipr

I expected a few "standard" things such as blocking ads neatly, allow whitelisting, allow manually updating rules, etc. Assuming they can all do that, I've mentioned anything of note.

This is not a full review, but I have given each content blocker a score out of 5 points. 5/5 being the best.

1Blocker (3/5)

+ Seemed to have a lot of options.

- Had no way to refresh rules.

Ad Block Multi (3/5)

+ Seemed to have a lot of options.

+ Showed when the rules were updated

- Seems to not fully load. I got a constant "spinning animation" next to several rules.

Ad Control (3/5)

+ Supported syncing your settings (such as whitelist) between your devices using iCloud.

+ Has a "single ad" mode, allowing ad revenue to the site while still preventing too many cluttering ads.

Ad-Blocker (2/5)

- Did not seem to update CSS to hide where ads were (left empty blocks on the page).

- It prompted for in-app payment if you try to use some of the options.

- Had no way to refresh rules.

I would not recommend this.

Adamant (2/5)

- Had no/minimal options.

- Had no whitelist ability.

- Had no way to refresh rules.

I would not recommend this.

AdBlockX (1/5)

- Had no/minimal options.

- Had no whitelist ability.

- Allowed a lot of ads through!

I would definitely NOT recommend this one, at all.

BlockBear (3/5)

- Had no way to refresh rules.

Blockr (4/5)

+ Nothing of note. It's simple and works as expected.

This was my primary content blocker over the past few months.

Clearly (2/5)

- Had no/minimal options.

- Had no whitelist ability.

- Had no way to refresh rules.

I would not recommend this.

Crystal (2/5)

- Had no/minimal options.

- Had no whitelist ability.

I would not recommend this.

Freedom (2/5)

- Had no/minimal options.

- Had no whitelist ability.

- Had no way to refresh rules.

I would not recommended this.

Lionz (3/5)

+ Seemed to have lots of options.

- Had no way to refresh rules.

NeverAds (2/5)

- Had no/minimal options.

- Had no whitelist ability.

- Had no way to refresh rules.

I would not recommend this.

Privacy (5/5)

+ Seemed to have lots of options.

+ Gets past the Forbes ad block!

I highly recommend this!

Purify (5/5)

+ Seemed to have lots of options.

+ Gets past the Forbes ad block!

I highly recommend this!

This is what I've now made my new primary content blocker.

Rocket (3/5)

+ Seemed to have lots of options.

Silentium (4/5)

+ Nothing of note. It's simple and works as expected.

Vivio (2/5)

- Had no/minimal options.

- Had no whitelist ability.

I would not recommend this.

Wipr (2/5)

- Had no/minimal options.

- Had no whitelist ability.

I would not recommend this.