The phrase "as tangible proof" is correct and usable in written English.
It can be used when you want to emphasize that something serves as concrete evidence or a clear demonstration of a point or claim.
Example: "The signed contract serves as tangible proof of our agreement and commitment to the project."
Alternatives: "as concrete evidence" or "as clear proof".
"Rather, they brandished the book as tangible proof of Joseph Smith's divine calling".
The large green-threaded words "you win – I gain" served as tangible proof of the long hours Karen had spent alone in the hospital.
It will serve as tangible proof that the city can't just evade by saying it has no record of an application, which is part of the bureaucratic hell they have long subjected our clients to".
The disabled hulks of these carriers served the speakers at the village meetings as tangible proof of their claimed superiority over the Americans, despite all the formidable and sophisticated weaponry of the intruders.
Write down your feelings, your resentment, the name or names of the person(s) troubling you and take that piece of paper as tangible proof that you are going to move on.
("I think I enjoy winning elections as a tangible proof of respect and liking," she wrote to Mr. Peavoy).
For more technical details about their security you can refer to Telegram's site, but as a more tangible proof of the app's security for us non-specialists, the app's makers also set up a competition.
"I believe you mean the alleged labor camps, as there is no tangible proof of their use or even their existence," responds a representative of North Korea.
They offer tangible proof that music is atmosphere -- reverie -- as well as sound.
The celebrations went on long into the night as the Rapids supporters got their first tangible proof that the team really is getting better & better.
We had 15.2 million people join us as climate allies - very powerful and tangible proof that the people of the world wanted our world's leaders to act - but rather than doing so, they let the people of the world down.
