I just use an Excel spreadsheet.
I just had tires installed at a local shop, and they sent me a link to their own service history website, which keeps track of work done. My usual place for oil changes still hand writes everything, and doesn't send any info to CarFax.
I always keep my paper receipts in a folder, which is handy when selling a car. We sold a car last year, and the buyer had lots of questions about what work had been done on the car. I just handed him the folder and let him read through it. I had put the car up for sale at 3:30pm that day, and the guy who bought it drove an hour to come see it, arriving at 8:30pm. He drove home with it that night.