Which specific accent are you looking to improve?
Like this website illustrates , there are many of them!
provide an overview of the variety of the sounds of the English language on various levels: in time , with our transcriptions of historical ancestor forms of English, from present-day back to Late Modern English, Early Modern, Middle and Old English, as far back even as Proto-Germanic; over geographical space; by sociolinguistic context.
That being said, you can try some online resources: howjsay.com fonetiks.org acapela-group :
its Text to Speech Demo allows you to listen to a small selection of different accents.
english.stackexchange.com/users/110/VonC
Livemocha is a platform to study foreign languages.
For its spoken language module you record yourself speaking and other users on the site provide feedback.
english.stackexchange.com/users/373/alexsome
There is no such thing, in English, as a neutral accent.
Every accent gives some idea about the person speaking.
Even so called 'neutral accents' do so too.
Really all you should wish to do is either polish off some of the rougher edges of your own accent or choose a new accent that you like, one that you think is beautiful or reflects your character, and try to practice it.
In the past I have tried out some computerised speech tutors with my students.
In general I have been unimpressed by the methods or results.
english.stackexchange.com/users/10364/Rincewind42
There's a small, English city called Peterborough that's considered to have a neutral accent.
It became the UK's Call Centre Capital because businesses felt that people would prefer a neutral accent and that Peterborough had one.
I'm not sure how they decided what a neutral accent sounded like, or why they thought people would prefer it, but that was what happened.
english.stackexchange.com/users/32863/Carl Smith
Software - not sure about that but
you could tune your accent by ear.
Many American TV showns seems to use a homogomised accent, pick one and compare yourself against that.
Avoid "the Wire"
(I still need subtitles for that one) or anything with NYC gangsters.
english.stackexchange.com/users/2657/dave
You are looking for a program that would tell you if you are accent-free?
You cannot be accent free.
Everyone has an accent if we want it or not.
You can speak 'standard' language ( with correct textbook grammar ) but you will always not matter what have an accent.
Maybe precise what do you mean by 'accent-free'?
Free from the accent you live in?
Free from the accent you work within?
Even if you learn how to speak with a different accent perceived as normal, you would have an accent and won't be accent free according to people who have different accent.
It's a bit a of Sisyphean task to be honest.
english.stackexchange.com/users/31208/Canela
I have a query regarding enhancing my accent. I am searching for software in which I speak a paragraph and it compares my speech to find out whether it is accent-free or not.
Is there software that can determine whether I speak with a neutral accent?
english.stackexchange.com
<learning><accent>
english.stackexchange.com/questions/178
english.stackexchange.com/users/113/Zerotoinfinity
It's debatable whether there is such as a thing as a "neutral accent". However, a platform that might help analyse your speech is "LiveMocha", which is a platform for studying foreign languages. There are various ways to check you accent but remember there is no such thing as a neutral accent - everyone speaks with one kind of accent or another.
It's debatable whether there is such as a thing as a "neutral accent". However, a platform that might help analyse your speech is "LiveMocha", which is a platform for studying foreign languages. There is no such thing, in English, as a neutral accent. Maybe you could polish off some of the rougher edges of your own accent or choose a new accent that you like, one that you think is beautiful or reflects your character, and try to practice it.  You cannot be accent free. You can speak 'standard' English with correct grammar, but you will always have an accent.   
There is no such thing, in English, as a neutral accent  - you cannot be accent-free. It is generally agreed that there is no such thing as a "neutral accent" or "accent-free" and thus there is no software that will help you with this task.
Use the Livemocha platform to find out. There is no such thing as a neutral accent. Pick an American TV show and compare youself to that.
There is no such thing, in English, as a neutral accent. Maybe you could polish off some of the rougher edges of your own accent or choose a new accent that you like, one that you think is beautiful or reflects your character, and try to practice it.   You cannot be accent free. You can speak 'standard' English with correct grammar, but you will always have an accent.   
It is generally agreed that there is no such thing as a "neutral accent" or "accent-free" and thus there is no software that will help you with this task.