There can be several reasons why your Facebook Insights data does not match what you see in the Facebook Interface.
If your organic reach metric isn't matching what you see in Facebook, add the "viral reach" metric to your widget. The result of summing organic and viral reach will be equal or higher than the organic reach shown in Facebook. More info can be found here.
Fans online, new fans and removed fans
Fans online, new fans and removed fans are metrics for which we can only get statistics per day. To get a total, we therefore have to sum the daily values. This however means a fan can be counted multiple times, causing a different value in Swydo.
For the most correct image, we recommend visualising these metrics in graphs divided by day.
If you're reporting on unique metrics, in some cases metric values can be off. You can find more info and a list of all unique metrics here.
Facebook's interface shows data for the past x days, minus the last one. Take for example a date range of June 26th - July 2nd.
If this is selected in Facebook, their KPIs and KPI graphs would instead show data for June 26th till the July 1st. In Swydo we'd however include the 2nd of July. So, can therefore cause a difference between what you see in Facebook and what you see in Swydo.