Whatever tool you used, spend two minutes checking the output before you rely on it. These three tests catch essentially every extraction error, and you can run them in Excel on any converted file.
1. The running balance (the strong one)
If your statement has a balance column, this single test catches almost everything. Each row's balance must follow from the row above:
balance(n) = balance(n − 1) + credit(n) − debit(n)
In Excel, with balance in column E, debit in C and credit in D, put this in a spare column on row 3 and fill down:
=ROUND(E2 + D3 - C3 - E3, 2)
Every result should be zero. Any row that is not zero has a problem, and the amount tells you what: if it equals another transaction on the statement, a row was dropped; if it is a round-looking difference, a digit was misread.
The converter here runs this automatically and names the failing rows, but the formula is worth knowing for files converted elsewhere.
2. The totals
Most statements print totals for the period. Sum your debit and credit columns and compare.
=SUM(C:C) and =SUM(D:D)
This catches dropped rows even without a balance column, which makes it the fallback for card statements. It will not catch a transaction filed in the wrong column, since the totals still balance overall, so it is weaker than the first test, not a replacement for it.
3. The first and last rows
Look at the earliest and latest dates in the spreadsheet and compare them with the statement period printed on the PDF.
This catches the one failure arithmetic cannot: an extraction that is internally consistent but started or ended in the wrong place, because a page was skipped, or a header row was read as a transaction, or the opening balance line was dropped. The balances chain perfectly and the month is incomplete.
Two things worth a glance
Dates. Find a date after the twelfth of a month. If the statement covers April and your spreadsheet shows a transaction in a different month, the day and month have been swapped. Check this even when everything else passes, since it does not affect the balance chain at all.
Long numbers. If a reference or account number shows as something like 4.51E+11, Excel has converted it to scientific notation. That happens when a CSV is imported without setting the column to text, and it destroys the value. A real .xlsx avoids it, which is one reason to prefer that format.
When the checks fail
Do not start correcting cells by hand. A converter that got one row wrong usually got a class of rows wrong, and fixing the ones you spotted leaves the ones you did not.
Look at what the failures have in common instead. All on one page? A page-break problem. All rows with a blank debit? The column-shift bug. All at the start? A header row read as data. Once you know the pattern, either re-convert with a tool that handles it, or fix the whole class at once.
More on the underlying causes in why converters get it wrong.