TeamLogger - Simple, employee time-tracking software with automatic screenshots and activity level monitoring. $1 / User / Month.
Wikivoyage - the free worldwide travel guide that anyone can edit.
EntryAdvise.com - With EntryAdvise, you can check COVID restrictions, the entry requirements and useful travel info for all countries. It makes a good resource for frequent-travelers and backpackers.
Tripadvisor - The Tripadvisor mobile app is available for the Android and iOS platforms. It can be used to create reviews of hotels, restaurants, and to chat with other travelers on Tripadvisor forums.
FlightsLogic FareAPI - FlightsLogic provides Airline API, Flight API Integration, Flight Booking System to the travel agents, tour operators and travel companies worldwide.
Triptipedia - Triptipedia is a free collaborative encyclopedia of travel tips, where everyone can browse, save and share tips for better travel!