The Road to UChat: Building Uber’s Internal Chat Solution

Yeah, this excerpt is hilarious:

"...our team transitioned the company to a new solution capable of reliably delivering over one million messages per day to tens of thousands of users, all in one unified chat environment."

Yep, totally no other chat apps capable of those incredibly high numbers /eyeroll

enterprise chat products are expensive and don't fit at uber scale

Unless data privacy is an issue; if you started your company with questionable means, keeping your data and internal comms completely private could be a (paranoid) priority.

For one thing Slack takes and exceedingly long time from app open to being able to see messages. The guys over at Slack spend more time accommodating for loading catch phrases like 'you look nice today' than actually loading faster..

Because Slack is really expensive. Perhaps they concluded that an in house solution would be cheaper for them long term.

Likely privacy, cost and performance.

Slack is for "small" teams. They've got 10,000+ people in a 'group' since this isn't just for engineering staff, but also for drivers, customer support reps, etc.

These guys aren't split into lots of multiple teams under one big company, they're all just one 'team' with people leaving and joining fairly often due to driver turn-over.

Slack would cost ~$100,000 a month at those numbers as well (given enterprise level discounts).