Captcha microservice
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Demonstration Site -
Live API -

Captcha It
CaptchaIt is an SVG captcha service.
CaptcahIt can be used from any host/url (CORS) and allows for customization of the SVG, such as changing its width, height, background color or character count.

How to use

  1. Send a get request to host/captcha to obtain an id and SVG data.
  2. Display the SVG data on a website and obtain user input.
  3. Send the user id and user input to host/captcha in a JSON body as part of a POST request.
  4. The service will respond with a simple JSON object containing a boolean property called valid.


GET host/captcha

GET Request to obtain a CAPTCHA image and id.

Accepted URL parameters

  • width
    • int
    • optional
    • default = 150
    • Width of the SVG
  • height
    • int
    • optional
    • default = 50
    • Height of the SVG
  • size
    • int
    • optional
    • default = 4
    • max = 12
    • min = 1
    • Character count in the image
  • noise
    • int
    • optional
    • default = 1
    • max = 12
    • min = 0
    • Amount of noise in the image
  • background
    • string
    • optional
    • default = cc9966
    • Background color of the image. Must be a hex color without the leading # hashtag
  • color
    • boolean
    • optional
    • default = true
    • If the characters in the image should be colored

Response object has the fallowing properties

  • id
    • ID corresponding to the CAPTCHA request. Send it with the POST request
  • data
    • An <svg...>...</svg> HTML string containing the image

NOTE SVG ids will expire after 5 minutes.

POST host/captcha

POST request to validate a CAPTCHA against some text. Send parameters as a JSON body. Be sure to set the correct Content-Type header in the request.

Accepted body parameters

  • id
    • required
    • ID of the CAPTCHA request you would like to validate
  • text
    • required
    • Text you would like to validate against the CAPTCHA

Response object has the following properties

  • valid
    • Boolean that is true if text matches the SVG associated with the provided id. Is false if text does not match, or the provided id does not exist (or has expired).