Usability
Interface 
User-friendliness/complexity of the tool´s interface
Straightforward.
Time efficiency Time needed for mastering the „how-to“ of the tool and a production of a task
High.
Interface language(s) The number of languages in which the tool is currently available/adaptable to
Over 15 languages.
Respect for privacy Does the tool require registration? Who can see my data? Can I remain anonymous?
High. Vocaroo only collects email addresses and mobile numbers when users register or log in to a Vocaroo account. It might also collect IP addresses and web browser details in server log files, but only when necessary for debugging purposes. It uses this data to manage accounts and send news and updates, in case users opt-in to this. It also collects cookies for the purpose of keeping users signed in and storing account data. Vocaroo warns users that it has not been designed to share highly private or confidential audio, since the short, shareable, nature of the links does not provide the degree of security required for confidential purposes. It stores data with well-known cloud storage providers located within the European Union. Vocaroo acknowledges users’ rights to access, modify or correct personal data. It implicitly states compliance with the GDPR. It implicitly states compliance with the GDPR. See more here.
Saving work for future use Possiblity to save your or others´ work for reuse/reproduction
No, files expire after a few months.
Tailorability (If so, how?) Possibility of the tool to be used for a range of different activities (e.g. to what extent you can organize a project assignment with a central activity based on this tool)
Not much; Vocaroo can only be used to share voice messages.