A teenage boffin created damaging computer software used by cyber-hackers to crash 224,000 websites around the world from the bedroom of his family's home aged just 16.

Grant Manser, now 20, from Kidderminster, Worcestershire, set up the damaging software and sold it on the ‘dark web' to customers around the globe for as little as £4.99.

The ‘stresser' program worked by bombarding websites, servers and email addresses with so much information they crashed - with companies, schools, colleges and government departments among the victims.

Manser pleaded guilty to six charges under the Computer Misuse Act and four under the Serious Crime Act, but was spared jail as he received a suspended prison sentence.

Birmingham Crown Court heard how Manser's scheme operated over a four-year period between January 2012 and November 2014.

The defendant was arrested at the family's £170,000 detached home in November 2014 by officers from the Regional Cyber Crime Unit and computer equipment was seized.

It was found to contain four systems called Dejabooter, Vexstresser, netspoof and Refinedstresser, known in the computer world as DOS (denial of service) software.

When deployed these DOS programs flooded a chosen website, server or email address with so much data they could not cope, causing them to temporarily crash.

Manser sold the software via the ‘dark web' - the hidden internet used for criminal purposes - at prices ranging from £4.99 to £20.

Raj Punia, prosecuting, said Manser had 12,800 registered users and, of these, just under 4,000 had bought DOS packages.

They had then carried out 603,499 attacks on 224,548 targets.

One victim was Harrogate and Hull College which saw its computer network crash for 14 hours after a disgruntled student brought one of Manser's packages because he was unhappy at a detention.

Miss Punia said Manser accepted payment by PayPal and had a turnover of £50,000 during the period he was operating.

She said although it was widely acknowledged that ‘stresser' programs could be used legitimately by companies to test their own vulnerability, in this case Manser's software was ‘only designed for illegal criminal purposes'.

By the time he was arrested, Manser's business was doing so well he had started to advertise for staff. During police interviews, the teenager said he had got the idea after working for someone in the US and seeing how much money he made from the scheme.

Among the victims his customers targeted were companies, councils and government departments across the world, including Poland, France, other EU countries, the US and the Netherlands.

Jamie Baxter, defending, said Manser only made and sold the systems to make money, adding: ‘He is not a hacker.

The system doesn't take or hack any information from the websites being attacked.'

And he said he had built safeguards into the program to ensure that organisations on a ‘blacklist' were not attacked.

These included banks, any healthcare organisation, the police and the FBI.

‘He was only 16 when he started to do this and it was his immaturity and naivety which led him to commit these offences,' Mr Baxter said.

His client had not spent the £50,000 extravagantly, but on updating his computer equipment and also on his hobby of his motorbike, he added.

Judge Nicholas Cole sentenced Manser to two years' youth detention suspended for 18 months with the requirement to perform 100 hours' unpaid work and booter also pay £800 costs.

But he was spared jail after the judge accepted that he only did it for financial gain and was ‘young and naive'.