Maps showing the numbers of robberies, burglaries and vehicle crimes across London have been made available online.
People can type in their postcodes to get the statistics from their area and compare it to other parts of the city.
The Metropolitan Police said the £210,00 site could be expanded to include other types of crime, clean-up rates and local crime-fighting plans.
The maps have been used in cities like New York and it was a key part of mayor Boris Johnson's election manifesto.
The interactive maps will display monthly crime figures as well as historical data so the public can see yearly trends.
Hugely beneficial
It also has links to other sites including Safer Neighbourhoods Team web pages.
Mr Johnson said he thought the site would be "hugely beneficial" and help reduce crime by putting public pressure on the police.
"What we want to see is Londoners feeling that if they experience crime that it matters," he said.
"That it is not going to be lost in some great welter of statistics, that it's going to be recorded on the spot where it happened, that it's going to be publicly available and there's going to be pressure on the police to do something about it."
... we have found that in some cases Londoners' perception of crime is higher than the reality and the crime maps may help to reassure communities about the general safety of their local area
Deputy Commissioner Sir Paul Stephenson said: "There has been a growing and understandable appetite for people to know more about what crime is happening in their local areas.
"Indeed, we have found that in some cases Londoners' perception of crime is higher than the reality and the crime maps may help to reassure communities about the general safety of their local area."
The government has promised to publish maps for the whole of England and Wales by the end of this year.
Last month Crime and Policing Minister Tony McNulty said the new websites will help to foster a closer relationship between police and the community.
"The maps will show what happened last month and what the police have done about it and I think this will be a significant advance," he said.
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