“As of January 2022, the platform had approximately 40 million monthly active users.”[0]

In 2022 they had $30M expenses, so the cost is somewhat under $1/user/year.

They said the minimum donation is there to reduce the viability of scammers using it to check if a stolen credit card number is valid.

[0] https://en.wikipedia.org/wiki/Signal_Foundation

I wonder what is the salary of the executives.

Wonder no more, they have it in their 2022 tax filing:

Compensation

Key Employees and Officers Base Related Other

Jim O’leary (Vp, Engineering) $666,909 $0 $33,343

Ehren Kret (Chief Technology Officer) $665,909 $0 $8,557

Aruna Harder (Chief Operating Officer) $444,606 $0 $20,500

Graeme Connell (Software Developer) $444,606 $0 $35,208

Greyson Parrelli (Software Developer) $422,972 $0 $35,668

Jonathan Chambers (Software Developer) $420,595 $0 $28,346

Meredith Whittaker (Director / Pres Of Signal Messenger) $191,229 $0 $6,032

Moxie Marlinspike (Dir / Ceo Of Sig Msgr Through 2/2022) $80,567 $0 $1,104

Brian Acton (Pres/Sec/Tr/Ceo Sig Msgr As Of 2/2022) $0 $0 $0

from https://projects.propublica.org/nonprofits/organizations/824506840

Where is this $5.7M coming from? According to their tax filings in 2022, they paid their CEO $0: https://projects.propublica.org/nonprofits/organizations/824506840 (compensation section)

They are paying their CEO $0. Brian Acton, previously founder of WhatsApp, the guy who initially bankrolled the whole non-profit by a $50 million, 50 year, non-secured, 0% interst loan, later giving even more.

Source: https://en.wikipedia.org/wiki/Signal_Foundation#History

They pay some other C levels 400-600k. Source: https://projects.propublica.org/nonprofits/organizations/824506840 (compensation section)

Which site? Choose another instance if yours is unreliable. That’s the advantage of a federated system. Or just have a second account at another instance.