Following Kelly's (1955) personal construct theory, the repertory grid technique assumes people construe their view of the world in their own terms. A repertory grid is one way of getting to these constructs by using a set of elements and asking people how they differtiate these elements from each other.
Typically, three elements are selected from a larger set, and an interviewee is asked which two of these three are alike in some way and different from the other. The contrast given (for example, friendly versus unfriendly) is also used as a dimension to rate all elements, usually on a 7 point scale. Then the cycle repeats with another triad.
This web tool can be used during an interview to note the contrasting terms and rate each element using these terms as opposites on a scale. The advantage over using a paper form is the ease of generating a randomised grid for each interview. During the interview, rating of each element on their own scale is simplified (without typical confusion over the direction of the scale).
Additional information and source code are available on GitHub.