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Hi Edgar, Dmytro is correct, these tools aren't 100% accurate, they're just used to give you an indication of volume and quality. I suspect the main reason for this is the sheer volume of websites out there. To provide 100% accurate backlink data, they'd have to be crawling billions of pages every single day to detect new/lost links. It's not uncommon for a new link to take anywhere from a couple of days to 3 or 4 months to show up. As a general rule, the more popular a site (think New York Times, not a high-traffic spam directory), the faster your link will be seen, though not necessarily.