If you know rescues or shelters who are trapped by this, please convey that it IS possible to port to free, open, nonprofit software (= RescueGroups.org). I love RescueGroups software.
It's just a matter of exporting all your files into a spreadsheet-like format, and then setting up the new software to import them. There are people who can help them. PM me and I can hook them up with help.
HomeAgain is okay -- they'll market an upgrade plan but it's not necessary. It's a one-time $17 fee to register, but if the register uses their chips regularly, I think they discount it to $10 (on top of the cost of the chip). I find that expensive from a rescue perspective, since we would pay that registration. They seem set up on the assumption that the adopter will pay it, which leaves too much to chance IMHO. The customer service is at least pretty decent. They give free boxes of chips for every so many you buy, so that may balance out the fee -- that's a pretty good perk for rescues and shelters.
Avid/AKC is popular with breeders. They bug me because they charge you to update the registration, but other than that, they're quite good about helping get dogs back home. They have smart CS people who work hard to sleuth out ways to find people who have outdated information, which I really appreciate.
Things I love about Datamars/Petlink:
-price (even for small rescues buying in small quantity, it's just $10/chip with lifetime registration...and the price goes down with quantity)--they trounce others on price once activation/registration is figured in!
-no registration fee for adopters, ever
-no marketing garbage for adopters
-ease of registration (it takes a few key strokes in our RescueGroups interface to link a chip with an adopter electronic file, which then automatically registers the chip)
-customer service (they have smart people working for them who solve problems quickly--actual humans to talk to, not just a fax number that goes into the ether)
-their business model is microchips and animal tracking (both food animals AND companion animals), so all their R&D money and business resources are focused on getting that right (instead of being a pet insurance company that views microchips as a "marketing tool")
-they put aside a pool of money into trust to guarantee that if the company were to ever go under, their chip registry will be funded for the lives of all the animals in it
-they "get" rescues and have dedicated people to provide customer service to rescues -- they called me without prompting when our region went through the Great Flood of 2016 and wanted to send a supply of microchips (incl. registrations) to the disaster intake sites to help them keep track of "found" dogs and cats being fished out of floodwaters...which keeps animals from getting "lost" in the shuffle when they have to be transferred from one temporary emergency site to another (tracking "found" dogs is a HUGE problem in all the chaos--so access to free chips and a registration portal with a picture and ability to update what site the dog is currently, right down to a kennel number, in is a massive advantage)