A few I keep coming back to:
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alternativeto.net - type in any app/software you're paying for, get a crowd-sourced list of free or cheaper alternatives
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stopoverpaying.org - free car insurance comparison (saved me $1,300 last year)
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goodRx.com - prescription coupons your pharmacy has to legally honor - can be cheaper than using insurance
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percentagecalculator.net - single purpose website I use probably 7 times a week
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australian.museum/learn/animals - free and weirdly detailed animal factsheet library from the Australian Museum
