This weekend, techies and civic do-gooders will gather for the fourth time to work on projects to make Austin better. ATX Hack for Change, which began in 2013, will put teams to work on 37 projects, the most the three-day event has ever tackled.

The free event is technically sold out. As of this writing it has 476 registrants and 52 on a wait list, but Sarah Sharif, a spokeswoman for the event, said she expects that with cancellations and no-shows, there should still be room for those who want to participate and there will be a registration table on site. It

The event began as an Austin response to Code for America's National Day of Civic Hacking, which this year takes place on June 4.

Some of the projects set to be worked on this year include websites and apps to improve open government and transparency, such as "A Tax Receipt for the City of Austin,' which would show how property taxes are spent by the city. There will be projects in education and economic opportunity, such as "Texas Veteran Education Benefits," or community projects such as "Bots for a Change," a Facebook messenger bot to help nonprofits collect donations.

The event has a webpage with past projects and the impact they've made on the Austin community including "GENAustin," "Keep Austin Fed" and "Pet Alert ATX."

One of the projects for the weekend is a co-op ride-hailing app, in addition to apps for people to self-report during Austin Mobility Week, and one to try to make streets safer for cyclists and pedestrians. Transportation is a hot topic this year due to last month's Proposition 1 vote and the loss of Uber and Lyft services in Austin.

It is a controversy in the tech community that has not left the Hack for Change untouched. One of the event's past participants and an emcee at Hack for Change 2015, Keith Casey of Casey Software, decided not to attend this year and wrote a critical post on Medium and his website about Austin Mayor Steve Adler.

"Now we know that the city's engagement in the tech community is for show and good PR, not because they actually want us involved: The city of Austin is the hot girl from high school who wanted you to do her homework and then just go away," Casey wrote in the post, which was published on May 24.

On Wednesday, Casey said his decision not to participate has not changed. "It’s disappointing because I love the mission of the event but I won’t be used as a prop by the mayor," he wrote in an email.

Sharif said the event organizers had not heard from Casey since the post. "This is a community event. It’s not the mayor’s event," she said. "The project champions are people from the community. The people who work on the project are from the community. Our big thing is continuing on with promoting that."

The mayor did promote Hack for Change on Tuesday at a press conference , but Adler is not expected to participate in the hackathon itself. Michele Grieshaber, chief marketing officer of Silicon Labs,and Mark Strama, head of Austin's Google Fiber operations, will be keynote speakers on Friday.

Edited at 4:32 p.m. Thursday to correct: Mayor Adler will not be speaking at Hack for Change, as was stated in a previous version of this story.

Edited June 8: Open Austin has posted a recap of the event. You can check it out here.