Platforms and apps
If you want to do citizen science, you don't have to start from scratch. There is a wide range of ready-to-use solutions that help collect data. Some are immediately ready for use, but very specific for a certain type of data processing. Others are more open, but take a bit more work to get ready for use.
If you still want to build an app or platform yourself, you should not underestimate the costs. Several online tools allow you to make a rough calculation of development costs for mobile apps:
DoeDat is a platform (in Dutch) for analysing and transcribing images. It is in the hands of Botanic Garden Meise, but the platform is open to projects outside of this organisation as well.
DigiVol is the Australian platform on which DoeDat is based.
HackAIR is a European data and technology platform with citizen's measurements of air quality.
iNaturalist is an international platform for nature observations.
VeleHanden is a Dutch crowdsourcing platform for annotating and transcribing historical sources.
Waarnemingen.be is the Belgian and Dutch platform for sharing nature observations. Built-in automatic species recognition and a large group of voluntary moderators guarantee the quality of the entered data.
Zooniverse is perhaps the best-known platform for image annotation using citizen scientists. Zooniverse reaches a community of nearly 2 million citizen scientists with various projects. Most projects are in English, but a test version of the translation feature is also available.
Communication platforms for citizen science
You cannot collect data with these communication platforms, but they do allow you to reach large communities of enthusiastic citizen scientists with your project.
Iedereen Wetenschapper (Everyone Scientist): in Dutch, for Flanders and the Netherlands. Iedereen Wetenschapper can also help you communicate your project in their newsletter, build and maintain your own Facebook page for the project or publish an advertisement in EOS magazine.
SciStarter is an English-language communication platform on which citizen scientists can also create a personal profile, which automatically keeps track of how much and to which projects they contribute.
Ulrike Sturm, Sven Schade, Defining principles for mobile apps and platforms development in citizen science. (In: Research Ideas and Outcomes, Jan. 2014)