In the age of internet, your laziness (and good faith in people) might cost you time, money and nerve cells. Whenever you are entering into a business partnership, rental agreement or procure services, you are advised to check the other party. There is no 100% guarantee to avoid trouble but there are many easy ways to get close to a 100%.
You need to know the personal code or the business code of the other party and also consider that some of the checks can be purchased, some of them are only in Estonian.
In the Business Registry: https://ariregister.rik.ee/index?lang=eng you can check the company data - you will see the board member data for free and also how long the company has operated, other details have to be purchased. It is wise to use search engine check (google) for all the parties involved.
The tax debts can be checked here (using the personal code or a business code): https://maasikas.emta.ee/saqu/public/taxdebt .
There is a private portal that is run to provide information about the background of companies: https://www.inforegister.ee/en/features .
You can check for criminal and administrative penalties from this link: https://www.rik.ee/en/criminal-records-database
And finally you might want to check the register of court cases to see if your business partner has been involved in any court cases (in Estonian): https://www.riigiteataja.ee/kohtulahendid/koik_menetlused.html