How do indie hackers track and manage SaaS expenses?

We use Notion and have everything to a company card - it's easy for the founders but will become a problem as the team grows and you don't want to start giving out the company card details to everyone

I use Xero (https://xero.com/). Where possible, I have repeated invoices generated automatically. Those do need to be checked if the pricing changes, but it reduces data entry time. Bank feeds are automatically imported as well, which saves time.

I use FreshBooks now. Every Saturday, I spend 10-15 minutes going through emails and whatever new invoices are there gets added to Freshbook

Excel.

I'm a little crazy, but I do double-entry bookkeeping and keep a close eye on the balance sheet

For projects, I also additionally figure out unit economics to estimate the benefits.

I do all of this with google spreadsheets

UK here. No special tools. For my limited, I manually compile the monthly bank statements and corresponding invoices every year, print them off and hand them in a folder to my accountant.
For a new solo project, I've opened a seperate sole trader account that includes the ability to attach invoices etc., ready for self-assessment.

google sheets

Apple Wallet :D

Depends on how much transactions you have ;-) I normally start with a notion database or google spreadsheet to get an overview. Later when normally the project gets his own business/company I only use my book keeping tool (sevdesk, lexoffice,..) to keep track.

I've got a notion database where I track everything, but I also send it all to our accountant and he manages it in Exact. I probably don't need to maintain my own separate database of everything, but I tend to send it all to the accountant in one batch, so I use the database throughout the quarter as expenses accrue. Also sometimes nice to be able to quickly filter by expense-type and see the totals etc, it can also help for quickly forecasting for the quarter ahead when I'm doing basic calculations.

So far excel with cash flow sheet is getting work done.