You can give your assigned Lemon address to online merchants for order confirmations. That way, you can avoid having to forward receipts and spare your email account of newsletters and other junk from that merchant. Unfortunately, you can't send from the Lemon account, should you need to contact the merchant about a problem or forward your flight details to a friend. Lemon says that capability should be available by the end of March.
Lemon tries to categorize purchases, such as "food and dining" and "fast food" for Subway. That lets you analyze how you've been spending your money.
Lemon is good for tracking your spending online and off. You can do more with it than with Slice, though you'll need to do more work to keep it clean. It's good if you do a lot of shopping at brick-and-mortar stores.
Think of this service as a hybrid. Like Slice, OneReceipt scans your Gmail or Yahoo account for receipts. Like Lemon, you can forward receipts from any email account to an assigned address at OneReceipt.com. You can also send photos of paper receipts. OneReceipt categorizes your spending and gives you reports to analyze, just like Lemon.
OneReceipt was the most comprehensive of the three. Unfortunately, it doesn't execute as well as the others.
The comparison isn't entirely fair, as the other two services had several weeks' head start and much larger staffs than OneReceipt's four employees. Promised upgrades coming "soon" could help close the gap. I can't recommend OneReceipt yet, but I can't dismiss it entirely either.
For now, whether Slice or Lemon is better for you depends on whether you're mostly an online or an offline shopper. Or go with both, at least until OneReceipt can catch up.
Anick Jesdanun, deputy technology editor for The Associated Press, can be reached at njesdanun(at)ap.org.
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