Recaptcha2 recognition via sitekey

Table of contents


Added in version

CapMonster2 has the ability to recognize ReCaptcha2 without a browser. This allows CapMonster2 to be connected to a variety of third-party programs that require ReCaptcha2 recognition and that use the sitekey method to send captchas to recognition services. For this, an additional module CapMonster ReCaptcha SiteKey Addon was developed.

Connecting the ReCaptcha2 SiteKey Addon module

You can purchase the CapMonsterReCaptchaSiteKeyAddon module in your Personal Account. It is bought for a month on the same account on which the subscription to CapMonster2 was purchased.

On your ZennoLab account, it is enough to purchase one add-on for all CapMonster2 licenses.

After purchasing the CapMonsterReCaptchaSiteKeyAddon module, you need to restart CapMonster2 for it to load.

System requirements

The minimum system requirements for the addon to work are Intel or AMD, 2 cores, at least 2.2 GHz each core and 2 GB of RAM, operating system Windows 7+.

The recommended system requirements for the addon are Intel or AMD, 4+ cores, at least 3.1 GHz each core and 4 GB of RAM, operating system Windows 10 / Windows Server 2012+.

Sending ReCaptcha2 for recognition

From ZennoPoster

ZennoPoster has a special action for sending ReCaptcha2 for recognition via sitekey.

In the action settings, you need to select the recognition module and specify “In tab”.

On most sites, after selecting images, an autosubmit event appears. After its completion, the captcha is counted. For this, ZennoPoster has a setting “Enable autosubmit”.

If ZennoPoster cannot automatically determine the required sitekey, then instead of “In tab” select “Via SiteKey”. In this case, you will need to specify the sitekey key from the target site where the captcha is located, as well as the URL address of the site itself.

It is possible to find the sitekey on the site using the Web Developer Tool (DevTools) or in any Internet browser by pressing the F12 button.
In the content of the page, you will need to find a line with sitekey. For example, it might look like this:

From other programs

Captcha services emulation mode

You need to select the emulated services in the CapMonster2 settings. And then in the settings of your program choose to send the Recaptcha to one of these services.

CapMonster2 will intercept the request, recognize the captcha and return a response according to the API of the selected service.

Submitting a task directly to CapMonster2

From third-party programs, ReCaptcha2 needs to be sent for recognition by requests to the service API:

Some APIs require a VPN connection.

For example, a request might be like this:

The URL address of the recognition service is indicated here, in this example it is http://ip:port on which the CapMonster service is running (by default, port 80), the captcha service key, the captcha recognition method - via googlekey, the sitekeу itself, which is parsed from the site , and the URL of the page with the captcha.

In response, the captcha id is received - OK | CaptchaID, by which you can get the result with this query:

Requests sent to the service will be intercepted by the program and return the same response as from the service. Captcha recognition takes place on the remote ReCaptcha2 module on our server. For clicks on pictures, the program uses the built-in local browser, which automatically selects the most suitable user agent for ReCaptcha, and also supports a proxy that can be passed in a request when sending or set in the program settings.


For advanced configuration of the add-on module, a separate section is provided in the CapMonster2 settings.

Limits, resources, percentage and recognition rate

The number of recognized ReCaptcha2 per day depends on the version of the program:

CapMonster Pro ~ 45,000 ReCapctha2 in 24 hours;
CapMonster Standard ~ 11,000 ReCapctha2 in 24 hours;
CapMonster Lite ~ 2,200 ReCapctha2 in 24 hours.

The module uses very few processor resources - less than 1% during operation, and consumes up to 150 MB of RAM per thread, because when recognizing, a browser is used, in which ReCaptca2 is loaded and clicked.

Because Captcha recognition takes place on the remote ReCaptcha2 module, the recognition percentage will be the same as with normal recognition through the browser - from about 83% success depending on the type of task.

The average response time for a captcha depends on a specific site, the number of requests and proxies. Based on the testing results, the following recognition results were obtained:

  • Average recognition time: 40 seconds.

  • Minimum recognition time: 14 seconds.

  • Maximum recognition time: 254 seconds.