Platforms to make online experiments with counterbalancing There are a number of different interfaces to make an place experiments online, e.g. in questions Software for online psychological experiments that don&#39;t require users to download anything or Open source software for running Internet psychological experiments that collect reaction time data.

We have an experimental design that we'd share online, but we've found that one feature may be quite rare - namely counterbalancing. We have 4 conditions, and we'd like participants to be placed in these conditions so that we have more or less equal amount in each by the end. This can be difficult for web studies since it should only count the participants that successfully completed the trial.

Free and open source would be best, we don't have a designated budget to pay for setting up an experiment.
You could try www.gorilla.sc  It's cloud based software specifically designed for running cognitive psychology experiments online without needing to code.  It's not free, but it is affordable - £0.75 per participant.

Counterbalancing of various sorts is built in; randomisers, stimuli set counterbalancers, order counterbalancers.  It sounds like the simple randomiser set to balanced will do what you want.  As long as you stay on top of rejecting Ns that drop out, you'll get a balance in each condition.

There is a GUI questionnaire builder, task builder and experiment tree builder.  So you don't need to do any coding.  The vast majority of cognitive science task can be created in it very easily.

Full disclosure, I created Gorilla.