MONTREAL—After a historic week that saw city hall crumbling from the top down, with the resignation of Mayor Gerald Tremblay and his main lieutenant Michael Applebaum, the opposition is rejoicing.

During his dramatic resignation as chair of the executive committee on Friday, Applebaum claimed a 2004 report documented that the city paid up to 40 per cent more than was necessary on projects, and that his colleagues had voted to hide the document from the public.

“It's not true, we don’t want to hide anything, we're working for Montrealers,” said Richard Deschamps, the man chosen by the governing Union Montreal project to lead the city as of next Friday.

Across town in Riviere-des-Prairies–Pointe-aux-Tremble, members of the second opposition Projet Montreal were chanting with joy. With a byelection scheduled for tomorrow, they saw Union Montreal’s fall as their fortune.

Out stumping on Saturday, party leader Richard Bergeron said he sees Projet as the city’s best alternative.

He added that Applebaum’s announcement was just because the city’s former No. 2 was sour about being passed over as mayor in favour of Deschamps.

“If he had been chosen as the candidate he would still be there and happy and smiling and we would have never seen this famous paper,” said Bergeron, of Applebaum clutching the 2004 report as he resigned.

Meanwhile, opposition leader Louise Harel gave Applebaum credit.

“I agree that Montrealers deserve to know what happened in their city and in this way, I agree with Mr. Applebaum,” said Harel, the leader of Vision Montreal.

Unsure who to trust in the municipal area, citizen’s group Open Quebec was holding a hackathon on Saturday to fight corruption through computer applications.

“To make this data accessible to people, we use data visualization,” said Jonathan Brun, from Open Quebec.

The idea is to make sense of all the information available in hundreds of government databases. So what people are doing this weekend is trying to connect those databases using intelligent software and tools that allow them to detect when, for instance, a cost overrun happens on a project or when a certain entrepreneur has had multiple fraud judgements but keeps creating new companies.

It's work that anti-corruption crusader Jacques Duchesneau said will help clean up government.

“It is a democratic earthquake that we're going through right now,” said Duchesneau, who is the Coalition Avenir Quebec MNA for St-Jerome. “We cannot go on like that forever.”

The results of Sunday’s by-election in RDP will no doubt be an indication of whether or not the resignations last week at city hall carried a heavy cost for Union Montreal.