Jake Swords, 27, sent the social media post in revenge after a post which wrongly accused himself of stealing a motorbike.
Three days later an account called Frankie Swords - run by the Rushden man - posted a picture of the victim online alongside a caption saying: "Paedophile in Rushden. Be careful."
The post left the victim fearing for his safety and in the days after the incident he was approached by an unknown man in Sainsbury's and abused.
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In a victim impact statement, he said: "I do not know how many people have seen this post but I do not know what the potential repercussions could be.
"I fear for my family's safety."
Swords, of Tennyson Road, admitted grossly offensive communications on what would have been the day of his trial at Wellingborough Magistrates' Court last month.
Magistrate Richard Hawkins, who oversaw the case, said: "We acknowledge that this was a one-off posting. But it does not get any more toxic than calling someone a paedophile which I am sure you understand and is probably why you did it."
Swords again appeared before magistrates in Northampton on Monday (November 4) to be sentenced.
He was told he must pay his victim £100 in compensation and was handed a one-year community order with rehabilitation activities.
Swords - who a court previously heard posted in a "moment of madness" - must also pay a £120 fine, £100 in costs to the CPS and an £85 surcharge to fund victim services.