Here you will find some databases I found around the web. They're not the perfect source of truth but they can help you in assessing how to compensate your employees.
More than 4,000 people entered their salary in this spreadsheet (worldwide).
Reddit Tech Salary Sheet (Responses)
Another spreadsheet focusin on the French tech ecosystem. Around 1k people entered their salary in this document. (in french)
Grille de Salaires anonyme des startupers
More than 30,000 people participated to this survey 😱a real mine of gold! Focused on the US market even though you can find people from some other countries here and there.
Ask A Manager Salary Survey 2019 (Responses)
Another great ressource with around 3.5k lines from people all around the world but mainly focused on the US.