Not only is Fidelity a reliable provider, but their HSA is both transaction and fee free.
Fidelity is one of the most reputable financial services companies in the world with a rich history and an evolved product suite that has kept up with the pace of technology.
Employees that use their HSA can invest unused balances into hand selected funds that are transaction and fee free.
Fidelity also offers benefits administration services for companies that want a whole suite along with their HSA.
Fidelity's services don't cost any fees and there aren't any account minimums for employees.