What is the best/recommended CAPTCHA component for ASP.NET

Question

Does anyone have any recommendations for CAPTCHA components for use in ASP.NET projects?

score 26 · Accepted Answer · edited Jan 23 '19 at 16:27

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I've been using recaptcha for a couple of sites with great success. I really recommend it.

There is a recaptcha control for asp.net here.

I've also used this captcha with success.

edited Jan 23 '19 at 16:27

Jean-Paul

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answered Mar 30 '09 at 08:28

alexn

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recaptcha is great, but their .Net control doesn't support the ValidationGroup property in .Net 2.0 +... Which means the control doesn't work at all on my site! I am looking for a way around that. Suggestions welcome :) – TimS Nov 11 '09 at 15:06
Alexn - thanks for the tip, this worked a treat for me. Added the dll to the bin directory, added the reference and control to the page and away it went - piece of cake. – adrianos Nov 22 '09 at 00:47
The plugin has been moved to https://developers.google.com/recaptcha/docs/aspnet. – Joe Nov 05 '13 at 14:23
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Agree with @TimS - without ValidationGroup support you have to rely on Page.IsValid, so you don't know if it's the Catpcha field that's invalid or some other field - not very user-friendly. – Young Bob Dec 05 '13 at 10:40
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here is new updated link https://developers.google.com/recaptcha/old/docs/aspnet (for older versions, and a link to a new version) – deebs May 07 '15 at 18:30
Another disadvantage of recaptcha that it may be blocked in China by the Great Firewall – Varga Tamas May 11 '15 at 13:56
Website 'recaptcha.net' does not seem to exist anymore. – Jean-Paul Jan 23 '19 at 14:45

score 7 · Answer 2 · answered Mar 30 '09 at 14:08

Before you evaluate any captcha solutions you should develop a clear profile of your users. Needless to say, any captcha solution is going to make your site harder to use. If your users are older with vision difficulties deciphering a captcha can be extremely difficult if not impossible. Random characters vs real words, may impact your users. Native language may affect user's perception of what the character represents (special characters).

No recommendations here, but knowing your users and what they will tolerate and or are capable of, should have a significant impact on your decision.

Good point. What would you then recommend other than using a captcha control given the scenarios you mentioned? — Brendan Vogt, Dec 10 '13 at 05:55

score 3 · Answer 3 · edited Mar 26 '14 at 22:31

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How about BotDetect?

The free version is available as well while they don't force your visitors to solve 2 captcha words.

edited Mar 26 '14 at 22:31

Toni Frankola

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answered Sep 23 '13 at 13:54

sleepy librarian

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score 2 · Answer 4 · answered Jan 08 '12 at 02:02

I would second the Mondor's Captcha mentioned in the first answer. Unlike the reCaptcha, it is fully independent, you don't make a call to other website. Also, it allows asking for solving a simple equation (like "5 + 3") and while bots would answer "5+3", human would answer 8. Also, unlike the reCaptcha, you can customize it as much as you want and include your own alphabet (Cyrillic, Arabic, Chinese - whatever).

score 1 · Answer 5 · answered Aug 05 '13 at 11:30

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Recaptcha is a nice captcha to protect your forms if you want to take a dependency on Google.

Telerik has a great ASP.Net captcha control available that you should check out as well.

answered Aug 05 '13 at 11:30

Jeff Fritz

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Recaptcha challenge letters are very very difficult to read. Visitors are not like to read such challenges – SCC Mar 21 '14 at 06:22
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... and if you're a spammer you don't like it much either – Jeff Fritz Mar 26 '14 at 18:37

score 0 · Answer 6 · answered Mar 24 '13 at 12:22

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I am also using the recaptcha, and it is great!

Here is the link for the ASP.NET plugin/wrapper:

Using reCAPTCHA with ASP.NET

answered Mar 24 '13 at 12:22

Mikhail

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Recaptcha challenge letters are very very difficult to read. Visitors are not like to read such challenges – SCC Mar 21 '14 at 06:20
here is new updated link https://developers.google.com/recaptcha/old/docs/aspnet (for older versions, and a link to a new version) – deebs May 07 '15 at 18:30

score 0 · Answer 7 · answered Mar 26 '13 at 09:50

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You could try Picatcha - pretty cool to use and looks easy to implement. Images vs text. Fairly customisable

answered Mar 26 '13 at 09:50

JPThorne

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score 0 · Answer 8 · answered Apr 30 '15 at 13:04

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If you're using VB.NET as your base language (or even Classic ASP), I just found a great free CAPTCHA at TipsTrips.org. You customize the CAPTCHA you want and then download the code. The .NET download includes a ASHX handler file, two VB class files and an ASPX test page.

answered Apr 30 '15 at 13:04

Dan H.

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can we get the exact link please? – Cute Bear Jun 30 '15 at 11:25
The exact link is http://www.tipstricks.org. Which is the link I gave. – Dan H. Feb 16 '17 at 14:16
FYI, tipstricks is defunct and up for sale now. – KingOfAllTrades Jan 28 '19 at 21:22
If you're looking for vb.net, maybe try https://www.codeproject.com/Articles/142624/Captcha-for-aspx-using-VB-NET – MiscellaneousUser Feb 19 '19 at 14:10

What is the best/recommended CAPTCHA component for ASP.NET

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