GSTR 9 and 9A

before 31st december it is required to be file

GSTR 9 is the Annual Return for Regular Tax Payers under GST. The return is required to be furnished on or before 31st December following the close of the financial year. 

GSTR 9A is the Annual Return for Composition Tax Payers under GST. The return is required to be furnished on or before 31st December following the close of the financial year. 

is that possible to file our own or we need support of any other auditor?

in case your turnover is more than 2 crore then certification from auditor would be reuired

In My view form GSTR 9 which is being notify by council by Notification 39/2018 CT is going to be Toughest form to File.
because :
1.Have to provide Input detail for service & goods seperatly (Never provide by Taxpayer in monthly 3b)
2. Input claim has to be match with 2a (Never given chance to file GSTr2 taxpayer that he can accept or reject same)
3.Reversal of ITC detail in case of 17(5), & rule under 42, 43( Now the Taxpayer has not created any seperate heads for those reversalbin their book accounts means have to search for such entries in books)
4. Many Taxpayer has not filed the GSTR1 till date si recepient Taxpayer will never get reflected their purchase in 2A

And Many more ...... once you go through the form , you will find that how tough is the form is made