Validation is the process by which you will know who you are building a solution for (your customers), what they want it for and how much they need it.
In order to build a business on facts, not hypotheses, you will need to 'get out of the building' and test your hypothesis. This stage is your 'customer discovery' during which you must ask questions and obtain information from your customers to validate the initial hypothesis.
Source: Steve Blank
Online surveys are great validation tools.
You will build a questionnaire (survey) and conduct in-person and online interviews.
Then you will need to analyse the responses to inform the build of your product. Then and only then you can start developing your solution as you will know who you are building it for and that they are willing to use it.
Using online tools help you create surveys that you can post on your social media or by email and get people to fill in. This will complement greatly the in-person interviews that you will conduct, with the same survey of course so that you obtain consistent information to work from.
The following online tools help you collect the information in a easy to access spreadsheet, from which you can analyse the information you get. Once you collected plenty of information from your potential customers be sure to spend some time reviewing it to use it effectively for building your solution.
Survey Monkey allows you to create and send surveys with ease. Create any type of survey—from simple to sophisticated— with this powerful and easy-to-use survey builder.
This is another perfect tool to validate your Mashup project! You need to create an account and the free option lets you build a 10-question survey and obtain up to 100 replies.
Google Forms is a service offered by Google. Forms (surveys) are created by anyone with a Google Account. The form is saved on the user's Google Drive.
It is a very easy way to collect data online without much of a hassle. It provides you with a number of themes, to make the form look fancy and also a number of different controls (such as drop down, radio button, check box, date picker...)
You can share your form with others, and asks them to fill it out. All the responses to the form are saved in a spreadsheet file stored in Google Drive. Once you're done collecting responses, you can close the form and download the results.
It is free but you need a Google account.