Everytime I fact check someone like you who claims 'voter fraud' I find it's been debunked, thoroughly by multiple sources with hard facts.
There are cases of isolated fraud in almost all elections. They don't amount to squat and prove nothing.
All elections have irregularities, such as the 'hanging chads' in the 2000 election. Irregularities are much more common than isolated fraud cases.
However, the charge by Trump was that 'Democrats stole the election", and on that score, there is absolutely no good reason to think that there was a massive conspiracy conducted by Democrats to steal the election. No evidence has ever been produced that even remotely points to that falsehood. I'm certain I can debunk anything you throw at me (but do it one or two at a time, please).
However.......
I can defy it on pure logic/logistic grounds. To wit;
The very idea is absurd, given the massive degree of the decentralized nature of the general election. Among the several points I can address which underline the absurdity of it, the salient one is the very fact that Joe biden only won by some 80k votes in two key states. If Democrats were going to rig an election, allowing it to be won on such a few number of votes in two states that cannot be predicted at the outset would be implausible (given there are, initially, about a dozen or so states in which, in the final result, one or two would be the decisive vote, which cannot be known in advance, do, at the minimum, it would require a few hundred conspirators from both parties in about a dozen key states).
The point being, if the election were rigged, allowing it to be won by so few votes would be far to difficult to control, meaning that it could have gone the other way with such a nimble win, so if there were a rigging, the win would have been by a vote far greater than that, not to mention down ballot votes allowed Republicans to keep the house, and why would Democrats allow it? and why would Democrats allow control of the Senate by one or two seats? Such a slim margin in both houses doesn't spell 'rig' it spells 'organic result', so, on this ground, alone, it doesn't make a bit of sense. And, given the several hundred conspirators that would be required to pull it off, it would require people from both parties to go along with the scheme, as there are monitors in the process from both parties, watching the action.
And getting away with it would be well nigh impossible, with all those conspirators, given it would have to be planned, organized, months in advance, accounting for the varied systems in different states, and there would be whistleblowers. Where are the whistleblowers? there are NONE. No, the idea is absurd on it's face. I can only surmise that those who believe this CT are prone to Qanon, fake moon landing, 9/11 was an inside job, Obama was born Kenya, Hillary sold 20% of America's Uranium to the enemy, and Joe extorted Ukraine and took bribes, ad nauseum. And you wonder why we think you are kooks,